Embed Size (px)
Citation preview
The British Liquid Crystal Society
Conference 2015
BLCS 2015
Sheffield Hallam University
Monday 30th March to
Wednesday 1st April 2015
Sponsors
The British Liquid Crystal Society and Sheffield Hallam University are very
grateful to the sponsors, who have helped make this conference possible. Please
take a moment to look through the services our sponsors can provide for you.
Merck KGaA Frankfurter Straße 250 64293 Darmstadt Germany Tel.: +49 (0) 6151 72-0 Fax: +49 (0) 615172-2000
Taylor & Francis Customer Services Bookpoint 130 Milton Park Abingdon Oxon OX14 4SB UK Tel: +44 (0) 1235 400 524 Fax: +44 (0) 1235 400 525 Email (UK Trade): [email protected]
Kingston Chemicals Limited Department of Chemistry University of Hull Hull HU6 7RX UK. Tel: +44(0)1482465866 Fax: +44(0)1482466410 www.hull.ac.uk/kingston-chemicals/
Welcome
Dear Delegate Welcome to Sheffield Hallam University, hosts of the 29th Annual British Liquid Crystal Society Conference. The programme contains a broad mix of science and engineering, with a large number of contributing institutions and, as per tradition, a high proportion of student presentations - we are sure that there is something for everyone. As detailed below, all conference presentations and lunches will be in the Cantor Building of SHU's city campus, which is an easy walk from Sheffield Station. The conference hotel, the Jurys Inn is less than a hundred metres from Cantor. Evening meals will be in the Hallam View restaurant in SHU's main building. These locations, plus other places of interest (The Red Lion, The Millennium Gallery, …) are all marked on the map on the next page. We would like to thank all of the contributing presenters, both talks and posters, for providing such an interesting and varied set of Abstracts sharing their research and stimulating interesting discussions. We hope you enjoy the event.
Key Information
Conference Organisation
The local Conference Organiser is Doug Cleaver, MERI, Sheffield Hallam University. If you require assistance at any point, please contact him on [email protected]. Alternatively you can speak to Tim Spencer, Alireza Dastan or Fatima Chami (a SHU graduate) who comprise the rest of the home team. Registration
The registration desk will be located by the entrance foyer of the CANTOR BUILDING on Arundel Street. Poster boards and velcro will be available in the ground-floor Atrium space. Additionally, a luggage room will be available for safe storage on Monday 30th and Wednesday 1st please ask at the registration desk if you wish to make use this room. Lectures
These will all be held in the Cantor Building lecture theatre, room 9130 located on the first floor. Smaller rooms on the first floor of the Cantor building will be used for other gatherings. There is a permanent lectern set-up in 9130 with a Windows 7 PC containing full Microsoft Office, Adobe software and internet access. Please ensure that your presentations are uploaded at the very latest during the break before your presentation. Presentations may be downloaded or uploaded via external drives. Alternatively, personal laptops can be used for presentations, but it is your responsibility to ensure both power and video adapters are available. A standard PC serial cable is provided. Talks range in: 50 minutes Plenary 30 minutes Invited 20 minutes Contributed Please allow a few minutes of your allocated time for questions.
Posters
These are located in the ground floor Atrium of the Cantor Building, just to the left of the registration table. The Taylor and Francis stand will also be in this area. Poster boards are 1810 x 923mm. These will just fit an A0 in portrait orientation and comfortably hold A1 in portrait or landscape orientation. The poster boards are numbered - please check the programme to identify your number. The poster boards are brand new, so please use the velcro provided! Accomodation
The Jurys Inn hotel is less than 100 metres from the Cantor Building. It has its own underground car-park, which can be booked separately. Jurys Inn, 119 Eyre Street, Sheffield, S1 4QW Day-parking
If you require day-parking, we recommend you use the APCOA car park on Arundel Gate (opposite the Jurys Inn). This is also known at the Kit-Kat building (you'll understand why when you see it). If you "beep" you blue car-park token at the Cantor reception desk, then this just costs £3 per day. Leaving your car overnight will incur higher charges though. Lunches and Drinks Breaks
All lunches and drinks breaks will be held in the ground floor Atrium of the Cantor Building. Evening Meals
Both Evening meals will be held in Hallam View Restaurant located in the Owen Building on the university campus map. This is a 5 minute walk away from the Jurys Inn hotel and 3 minute walk from the Cantor Building conference venue - unless you stop off at the Red Lion en-route. Juice will be provided on the Monday evening. Juice and wine will be provided on the Tuesday evening. WIFI
Eduroam is available throughout the SHU Campus. Alternatively, individual logins to the SHU-GUEST Wi-Fi server can be obtained from the Registration Desk or the Conference Organisers.
Sheffield Hallam University Campus Map & Getting About
Some upcoming LC dates for the diary
Event: SID Display Week 2015 When: Sunday, May 31- June 5, 2015 Location: San Jose, CA, USA Link: http://www.displayweek.org/
Event: Chirality at the Nanoscale workshop When: Thursday, Jun 4-5, 2015 Location: The Nanoscale workshop, LCI, Kent State University (OH), USA Link: http://www.lcinet.kent.edu/conference/25/index.php
Event: Gordon conference on liquid crystals: Liquid Crystallinity in Soft Matter at and Beyond Equilibrium When: Sunday, Jun 21-26, 2015 Location: University of New England, 11 Hills Beach Rd, Biddeford, ME 04005, United States Link: http://www.grc.org/programs.aspx?id=11481
Event: 15th International Conference on Ferroelectric Liquid Crystals: Challenges in polar self-assembling systems When: Sunday, Jun 28-July 3, 2015 Location: Prague, Czech Republic Link: http://palata.fzu.cz/flc15/
Event: IMID 2015 When: Tuesday, Aug 18-21, 2015 Location: Daegu, South Korea Link: http://www.imid.or.kr/
Event: European Conference on Liquid Crystals (ECLC) 2015 When: Saturday, Sep 7-11, 2015 Location: Manchester, UK Link: https://www.meeting.co.uk/confercare/eclc2015/
Event: 8th International Liquid Crystal Elastomer Conference (ILCEC15) When: Friday, Oct 2-7, 2015 Location: Erice, Italy Link: http://people.sissa.it/~desimone/iWeb/ILCEC15/Welcome.html
Event: The 22nd International Display Workshops When: Wednesday, Dec 9-11, 2015 Location: Otsu, Japan Link: http://www.idw.or.jp/
Event: Pacifichem 2015 with Symposium #447 on Self-Organization: Novel Mesogens and Applications When: Tuesday, Dec 15, 2015 Location: Honolulu, HI, USA !! Link: http://www.pacifichem.org/
Event: 30th BLCS Meeting When: Monday, Mar 21-23, 2016 Location: UK Link: http://blcs.eng.cam.ac.uk/
Programme for BLCS 2015
DAY ONE - Monday 30th March
Time Location Event Title Speaker
10:30 Cantor Entrance Registration
12:00 Cantor Atrium Lunch & Poster put-up / BLCS Committee Meeting Cantor 9137
Session 1 - Liquid Crystal Nanoparticle Systems - Chair Doug Cleaver
13:00 Cantor 9130 Welcome / Opening Doug Cleaver
13:05 Cantor 9130 Plenary 1 Liquid-Crystal-Directed Nano-Assemblies Linda Hirst
13:55 Cantor 9130 Talk 1 Colloids in Blue Phase Liquid Crystals Anne Pawsey
14:15 Cantor 9130 Talk 2
Computer simulations of an anionic chromic dye: spontaneous symmetry breaking to form chiral aggregates and the formation of a novel smectic phase
Romnik Thind
14:35 Cantor Atrium Drinks
Session 2 - Competing Components And Environments - Chair Ingo Dierking
14:55 Cantor 9130 Invited 1 What does a Liquid Crystal Do in a Gyroid? Tim Atherton
15:25 Cantor 9130 Talk 3 Design and investigation of a gold nanoparticle side-chain liquid crystal polymer nanocomposite
Olusegun Amos
15:45 Cantor 9130 Talk 4 A combined experimental and computational study of anthraquinone dyes as guests within nematic liquid crystal hosts
Mark Sims
16:05 Cantor 9130 Talk 5 Multiscale models of metallic inclusions in nematic liquid crystals
Thomas Paul Bennett
16:25 Cantor 9130 Talk 6 Further tricritical and antinematic behaviour in a revisited mildly repulsive Straley model
Fulvio Bisi
16:45 Cantor 9130 BLCS AGM 2015
Session 3 - Split Session
17:00 (parallel)
Cantor 9131 "On the future of liquid crystals and optics" discussion Dr Simon Crook, Senior Manager EPSRC
Cantor Atrium Poster Session 1
18:00 Check-in at Jurys Inn Hotel (Arundel Gate) & Drinks Red Lion (Charles Street)
19:00 Hallam View Evening Meal
Programme for BLCS 2015
DAY TWO - Tuesday 31st March
Time Location Event Title Speaker
Session 4 - Lyotropics - Chair Helen Gleeson
9:00 Cantor 9130 Plenary 2
2015 Sturgeon Lecture:
Structure and Lyotropic Liquid-Crystalline Phase Behaviour of Lipid Membranes
John Seddon
9:50 Cantor 9130 Talk 7 Origin of Chirality in the Triple Network Tri-continuous Cubic Phase Formed by Achiral Rod-like Molecules
Xiangbing Zeng
10:10 Cantor 9130 Talk 8 Coarse Grained Modelling of the Phase Behaviour of Non-Ionic Surfactants with the SAFT-g force field
George Jackson
10:30 Cantor Atrium Drinks
Session 5 - Bent Cores AND Dimereric Mesogens - Chair Andrew Masters
10:50 Cantor 9130 Plenary 3
BLCS Young Scientist Award Lecture:
Understanding unusual electric field-driven reorganisations in the mesophases of bent-core liquid crystals
Mamatha Nagaraj
11:40 Cantor 9130 Talk 9
Synthesis and properties of asymmetric dimeric materials with lateral and terminal fluorine substituents for dual frequency liquid crystal mixtures
Dave Allan
12:00 Cantor 9130 Talk 10 Liquid crystal dimers: A molecular level and mesoscale study
Martin Walker
12:20 Cantor 9130 Talk 11
Raman scattering studies of orientational order parameters in liquid crystalline dimers exhibiting conventional and twist-bend nematic phases
Vitaly Panov
12:40 Cantor Atrium Lunch / BLCS Committee Meeting Cantor 9137
Session 6 - Gray Medalists - Chair Peter Raynes
13:40 Cantor 9130 Plenary 4 From Biaxiality to Bistability and Back Again Cliff Jones
14:30 Cantor 9130 Plenary 5 Solid Liquid Crystals Mark Warner
15:20 Cantor Atrium Drinks
Session 7 - Liquid Crystal Dynamics - Chair Tim Spencer
15:40 Cantor 9130 Talk 12 Complex Rheology of Nematogenic Fluid; Connection to Elastic Turbulence
Buddhapriya Chakrabarti
16:00 Cantor 9130 Talk 13 Interfacial motion by mean curvature in liquid crystals
Amy Spicer
16:20 Cantor 9130 Talk 14 A computationally efficient Q-tensor model with flow for nematic liquid crystals
Yogesh Kumar Murugesan
16:40 Cantor 9130 Talk 15 Rheology of Cholesteric Liquid Crystalline Phases
Oliver Henrich
Session 8 - The Posters
17:00 Cantor Atrium Posters - with juice, beer and wine served from 17:30 onwards
18:30 Freshen up / Red Lion tipple
19:00 Hallam View Conference Dinner
Programme for BLCS 2015
DAY THREE - Wednesday 1st April
Time Location Event Title Speaker
Session 9 - Application And Applications I - Chair Verena Gortz
9:00 Cantor 9130 Talk 16 Anisotropic Dielectrophoresis – Nematic Liquid Crystals
Antariksh Saxena
9:20 Cantor 9130 Talk 17 Bleaching wave dynamics in photobending Chen Xuan
9:40 Cantor 9130 Talk 18 Graphene based electrodes for electrically switchable liquid crystal contact lenses
Sarabjot Kaur,
10:00 Cantor 9130 Talk 19 The investigation of mixtures of functionalized azocines – can LC phase behaviour be promoted by irradiation?
James Hussey
10:20 Cantor Atrium Drinks
Session 10 - Application and Applications II - Chair Carl Brown
10:40 Cantor 9130 Talk 20 Improving the optical performance of liquid crystal contact lenses by implementing axial alignment
James Bailey
11:00 Cantor 9130 Talk 21 Acousto-optics in dispersed LC systems for applications in ultrasonics
Oksana Trushkevcyh
11:20 Cantor 9130 Invited 2 Myelin: 19th Century Microscopy, Giant Squid (and a Duel with Bismarck)
John Lydon
11:50 Cantor 9130 Prizes and Closing
12:00 Cantor Atrium Lunch, poster take-down and farewells.
Plenary & Invited Talks
BLCS 2015 Talks Presenting
Author
Other Authors Affiliations
Plenary Speakers (50 mins)
PI 1 Liquid-Crystal-Directed
Nano-Assemblies
Linda Hirst - University of
California,
Merced, USA
PI 2 Structure and Lyotropic
Liquid-Crystalline
Phase Behaviour of Lipid
Membranes
J.M. Seddon - Imperial College
London
PI 3 Understanding unusual
electric field-driven
reorganisations in the
mesophases of bent-core
liquid crystals
M. Nagaraj - University of
Manchester
PI 4 From biaxiality to
bistability, and back again
J. Cliff Jones - University of
Leeds
PI 5 Solid Liquid Crystals Mark Warner - University of
Cambridge
Invited Speakers (30 mins)
I 1 What does a Liquid Crystal
Do in a Gyroid?
Tim J Atherton - Tufts
University,
Medford, MA,
USA
I 2 Myelin: 19th century
microscopy, giant squid
(and a duel with
Bismarck).
John Lydon - The University,
Leeds
Contributed Talks
BLCS 2015 Talks Presenting
Author
Other Authors Affiliation
(presenter)
Regular Speakers (20 mins)
T 1 Colloids in Blue Phase
Liquid Crystals
Anne Pawsey Paul. S. Clegg University of
Edinburgh
T 2 Computer simulations of
an anionic chromic dye:
spontaneous symmetry
breaking to form chiral
aggregates and the
formation of a novel
smectic phase
Romnik Thind Mark R. Wilson Durham
University
T 3 Design and investigation of
a gold nanoparticle side-
chain liquid crystal
polymer nanocomposite
Olusegun Amos G. H. Mehl University of
Hull,
T 4 A combined experimental
and computational study of
anthraquinone dyes as
guests within nematic
liquid crystal hosts
Mark Sims L. C. Abbott, S. J.
Cowling, J. W.
Goodby, and J. N.
Moore
The
University of
York
T 5 Multiscale models of
metallic inclusions in
nematic liquid crystals
Thomas Paul
Bennett
G. D’Alessandro,
K.R. Daly
University of
Southampton
T 6 Further tricritical and
antinematic behaviour in a
revisited mildly repulsive
Straley model
Fulvio Bisi G. De Matteis and
S. Romano
Università di
Pavia, Italy
T 7 Origin of Chirality in the
Triple Network Tri-
continuous Cubic Phase
Formed by Achiral Rod-
like Molecules
Xiangbing Zeng G. Ungar, F. Liu,
C. Dressel, M.
Prehm and C.
Tschierske
University of
Sheffield
T 8 Coarse Grained Modelling
of the Phase Behaviour of
Non-Ionic Surfactants with
the SAFT-g force field
George Jackson O. Lobanova, C.
Herdes and E. A.
Müller
Imperial
College
London
T 9 Synthesis and properties of
asymmetric dimeric
materials with lateral and
terminal fluorine
substituents for dual
frequency liquid crystal
mixtures
Dave Allan M. Hird University of
Hull
T 10 Liquid crystal dimers: A
molecular level and
mesoscale study
Martin Walker Mark Wilson Durham
University
T 11 Raman scattering studies of
orientational order
parameters in liquid
crystalline dimers
exhibiting conventional
and twist-bend nematic
phases
Vitaly Panov Zhaopeng Zhang,
Mamatha Nagaraj,
Richard J. Mandle,
John W. Goodby,
Geoffrey R.
Luckhurst, J. Cliff
Jones and Helen F.
Gleeson
University of
Manchester
T 12 Complex Rheology of
Nematogenic Fluid;
Connection to Elastic
Turbulence
Buddhapriya
Chakrabarti
R. Mandal, D.
Chakraborty, and
C. Dasgupta
Durham
University
T 13 Interfacial motion by mean
curvature in liquid crystals
Amy Spicer Apala Majumdar University of
Bath
T 14 A computationally efficient
Q-tensor model with flow
for nematic liquid crystals
Yogesh Kumar
Murugesan
D’Alessandro G
and De Matteis G
University of
Southampton
T 15 Rheology of Cholesteric
Liquid Crystalline Phases
Oliver Henrich K. Stratford, M.E.
Cates and D.
Marenduzzo
University of
Edinburgh
T 16 Anisotropic
Dielectrophoresis –
Nematic Liquid Crystals
Antariksh
Saxena
C. Tsakonas, I.C.
Sage, G. McKay,
N.J. Mottram, R.P.
Tuffin and C.V.
Brown
Nottingham
Trent
University
T 17 Bleaching wave dynamics
in photobending
Chen Xuan Mark Warner University of
Cambridge
T 18 Graphene based electrodes
for electrically switchable
liquid crystal contact lenses
Sarabjot Kaur D. Mistry, H.
Milton, I. M. Syed,
J. Bailey, Y. J.
Kim, K. S.
Novoselov, C. J.
Jones, P. B.
Morgan and H. F.
Gleeson
University of
Manchester
T 19 The investigation of
mixtures of functionalized
azocines – can LC phase
behaviour be promoted by
irradiation?
James Hussey G. H. Mehl University of
Hull
T 20 Improving the optical
performance of liquid
crystal contact lenses by
implementing axial
alignment
James Bailey S. Kaur, D. Mistry,
H. F. Gleeson and
J.C. Jones
University of
Leeds
T 21 Acousto-optics in
dispersed LC systems for
applications in ultrasonics
Oksana
Trushkevcyh
Tobias J. R.
Eriksson, Silvaram
N. Ramadas and
Rachel S. Edwards
University of
Warwick
Posters
BLCS 2015 Posters Presenting
Author
Other Authors Affiliations
P 1 Turbulent Textures - Art
with Liquid Crystals
Ingo Dierking - University of
Manchester
P 2 Using DPD Simulation to
Study Phase Behaviour of
Liquid Crystal-Gold
Nanoparticle Composite
Materials
Sarah Gray Mark R. Wilson Durham
University
P 3 All Optical Switching of
Nematic Liquid Crystal
Films Driven by Localized
Surface Plasmons
Linda S Hirst - University of
California,
Merced, USA
P 4 High-Speed Microscope
Imaging of Liquid Crystal
Dynamics
T. J. Atherton C. Burke, D.
Emerson, Y. Jin, J.
Guasto and J. H.
Adler
Tufts
University,
MA, USA
P 5 Synthesis and Properties of
Novel Liquid Crystals with
Bulky Terminal Groups
Designed for Bookshelf
Geometry Ferroelectric
Mixtures
Rami Pasha Michael Hird University of
Hull
P 6 Homeotropic alignment in
switchable optical power,
liquid crystal contact lenses
D. Mistry I. M. Syed, S.
Kaur, H. Milton,
J.Bailey, J.C.
Jones, P. B.
Morgan,
J. H. Clamp and H.
F. Gleeson
University of
Manchester
P 7 The dynamic response of
nematic devices with an
unconventional geometry
Marianna
Minarova and
Shajeth
Srigengen
Cliff Jones and
Helen F. Gleeson
University of
Manchester
P 8 Measuring the temperature
dependence of the
anisotropic viscosity of
nematic liquid crystals
using laser tweezer
techniques
David L. Wei Mark R.
Dickinson, James
Bailey, Cliff Jones
and Helen F.
Gleeson
University of
Manchester
P 9 Molecular Dynamics
Simulation of Fibre
Formation
Alireza Dastan Doug Cleaver Sheffield
Hallam
University
P 10 Polarized Raman
Spectroscopy
Measurements of Liquid
Crystal Order Parameters
Zhaopeng
Zhang
Helen F Gleeson University of
Manchester
P 11 Novel Resists for
Nanofabrication on
Insulating Substrates
Karolis
Virzbickas
Farhan Hasan,
Greg O’Callaghan,
Dennis Zhao, Jon
A. Preece and
Alex P. G.
Robinson
University of
Birmingham
P 12 Structure and organisation
in chromonic phases: MD
simulation study of Azo
dyes in aqueous solution
F. Chami M.R. Wilson Durham
University
P 13 AFM study of
supermolecular dendritic
liquid quasicrystals
R. B. Zhang X. B. Zeng, V.
Percec and G.
Ungar
University of
Sheffield
P 14 Hexagonal Close Pack
Structures in Thermotropic
Liquid Crystals
M. H. Yen J. Chaiprapa, X.
Zeng, L Cseh, G.
H. Mehl, and G.
Ungar
University of
Sheffield
P 15 Chessboard and Wigwam
phases in X-Shaped
Polyphiles
Huanjun Lu Feng Liu,
Xiangbing Zeng,
Goran Ungar,
Hergold Ebert and
Carsten Tschierske
University of
Sheffield
P 16 Novel mesomorphic
behaviour of a chirally-
doped liquid crystal dimer,
exhibiting the twist-bend
nematic phase
Craig T.
Archbold
Richard J. Mandle,
Edward J. Davis,
Stephen J.
Cowling and John
W. Goodby
The
University of
York
P 17 Investigation of the
Electric Field-Induced
Behaviour of Biaxial,
Smectic Liquid Crystals
using a Phase Sensitive
Detection Method
J. W. Foster and
J. Ish-Horowicz
V. P. Panov, M.
Nagaraj and J.C.
Jones
University of
Manchester
P 18 UV stability of liquid
crystal lasers during
polymer stabilisation
Philip J.W.
Hands
Shuyu Yang and
Michael P. Shaver
University of
Edinburgh
P 19 The investigation of
mixtures of dimers forming
a N and a Nx/tb phase
E. Ramou Z. Ahmed, C.
Welch and G. H.
Mehl
University of
Hull
P 20 Liquid Crystal Infiltrated
Gyroid Optical
Metamaterials
J.A. Dolan T.J. Atherton, J.J.
Baumberg, U.
Steiner and T.D.
Wilkinson
University of
Cambridge,
P 21 Developing Conductive
Organic Molecular Resists
for Nanofabrication of
Insulating Materials
Dennis Zhao Greg O’Callaghan,
Owen Jones,
Farhan Hasan,
Karolis
Virzbickas, Jon A.
Preece and Alex P.
G. Robinson
University of
Birmingham
P 22 Polarization-independent
switchable liquid crystal
lenses based on the
dark conglomerate phase
M. Nagar and H.
F. Gleeson
H. Milton, S. Kaur,
J. C. Jones and P.
B. Morgan
University of
Manchester
P 23 Colloid – Liquid Crystal
Gels
T. A. Wood J. S. Lintuvuori, A.
B. Schofield, D.
Marenduzzo and
W. C. K. Poon
University of
Edinburgh
P 24 The effect of a methylene
link in the flexible spacer
of liquid crystal dimers
Jordan P
Abberley
John MD Storey
and Corrie T imrie
University of
Aberdeen
P 25 Application of EPR
Spectroscopy and
Molecular Dynamics
Simulations to a Lyotropic
Liquid Crystal – A
Combined Approach
Christopher
Prior
Vasily S.
Oganesyan
University of
East Anglia
P 26 Conductive Resists for
Nanofabrication on
Insulating Substrates
F. Hasan G. O'Callaghan,
J.A. Preece and
A.P.G. Robinson
University of
Birmingham
P 27 Numerical Modelling of
Cholesteric Droplets
Menyang Yang Prashant Patel, F.
Anibal Fernandez
and Sally Day
University
College
London
P 28 A c2mm Liquid Crystal
Phase Formed by Dimer
Molecules
Warren
Stevenson
Ziauddin Ahmed,
Xiangbing Zeng,
Goran Ungar and
Georg Mehl
University of
Sheffield,
P 29 An isothermal nematic to
twist-bend nematic phase
transition
Daniel A.
Paterson
A. Martinez-
Felipe, R. Walker,
J. M. D. Storey,
and C. T. Imrie
University of
Aberdeen
PI 1
Liquid-Crystal-Directed Nano-Assemblies
Linda Hirst UC Merced, University of Califormia
Experiments and theory focused on understanding the interactions between nanoscale
particles and liquid crystal fluids has been a recent area of growth in the field, in particular in
the context of improving nano-particle dispersions to produce stable composite materials.
Another promising direction has been to take advantage of liquid crystal phases to induce
spatial organization of nano-particles by a bulk assembly method. I will review recent work
in these two areas by our group and others, in particular looking at a new methodology
developed in our lab to form nano particle membranes and capsules using mesogen-
functionalized quantum dots.
PI 2
Structure and Lyotropic Liquid-Crystalline
Phase Behaviour of Lipid Membranes
J.M. Seddon a
aChemistry Department, Imperial College London, Exhibition Road, London SW7 2AZ, UK
Lyotropic liquid crystals of 1-, 2-, or 3-dimensional periodicity spontaneously assemble when lipids
are mixed with solvent under various conditions of temperature, pressure and hydration. Although
biomembranes are generally based on the fluid lamellar phase, there is increasing evidence that
curved membrane structures such as the inverse cubic phases may be present in cell membranes,
and/or may facilitate cellular processes such as endo- and exocytosis, and fusion.
We have studied the effect of chain branching on the phase behaviour of a series of synthetic β-D-
glucosides derived from Guerbet alcohols, whose total hydrocarbon chain length ranged from C8 to
C24. A wide range of liquid-crystalline phases was observed, with the C16 Guerbet glucoside (i.e. -
Glc-C10C6) forming an Ia3d cubic phase of space group in excess aqueous solution, which is very
unusual behaviour.
Monoacylglycerols have proved to be invaluable for in-cubo crystallization of membrane proteins.
We have studied the effect of hydrostatic pressure on the L – Ia3d cubic transition of monolinolein
at a range of hydration. Pressure is found to stabilize the lamellar phase over the cubic phase, and at
fixed pressure, increasing the water content causes the coexistence region to move to lower
temperature.
We have previously shown that by addition of weakly-polar amphiphiles such as diacylglycerols to
phospholipids, one can tune the interfacial curvature to be strongly inverse, leading to the formation
of a discontinuous cubic phase of spacegroup Fd3m, with a structure based upon a complex close
packing of inverse micelles. We have investigated the effect of hydrostatic pressure on the structure
and stability of this phase, and have discovered a number of novel effects. We also discovered a
lyotropic phase of space group P63/mmc, whose structure is based upon a 3-D hexagonal packing of
quasi-spherical inverse micelles, in a hydrated mixture of dioleoylphosphatidylcholine,
dioleoylglycerol, and cholesterol.
We discovered a novel inverse ribbon phase in the branched-chain polyoxyethylene surfactant
system tetradecyloctadecyl-tetraoxyethylene ether (C14C16EO4) in excess water. This phase is
stabilised by the application of hydrostatic pressure. The lattice parameters of the inverse ribbon
phase were found to vary with pressure, with the structure becoming increasingly distorted away
from 2-D hexagonal symmetry (b/a = √3) with increasing pressure.
PI 3
Understanding unusual electric field-driven reorganisations in the mesophases
of bent-core liquid crystals
M. Nagaraj
aSchool of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
Although usually associated with rod or disk like molecules, liquid crystal phases have been
observed for organic molecules with a variety of different and unconventional anisotropic shapes.
Amongst these, bent-core mesogens have been considered as one of the most fascinating classes
due to their wide range of unique mesophases and unusual physical properties not exhibited in more
conventional liquid crystals. Indeed, even the well-known nematic phase formed by bent-core
molecule, exhibits distinct physical properties such as enhanced cybotacticity, anomalous elastic
constants, and large flexoelectricity and spontaneous deracemization, to name just a few.
I will present some of the unusual electric field-driven transformations seen in the lamellar
mesophases formed by bent-core molecules. This will mainly include SmAPR/A/F, SmCS/APA/F and
dark conglomerate phases. Particularly, a detailed investigation of an unusual DC phase observed in
an oxadiazole based achiral BCLC will be described. The DC phase exhibits amazing physical
properties, including an electric field tuneable chiral domain structure [1,2] and a large reduction of
refractive index [3,4], while maintaining an optically dark texture when observed under crossed
polarisers. The transformations are seen irrespective of the frequency of the applied electric field,
type of the waveform and the thickness or the geometry of the device used. The nature of the
behaviour has been investigated by various techniques such as optical microscopy, conoscopy,
circular dichroic and Raman spectroscopies, electro-optics and dielectric spectroscopy and small
angle X-ray scattering. Based on the results, a model of the DC phase will be described where in the
ground state the nanostructure of phase exhibits an anticlinic antiferroelectric organization. Under
an electric field, it undergoes a molecular rearrangement without any gross structural changes
leading to an anticlinic ferroelectric order while keeping the overall sponge-like structure of the DC
phase intact.
References 1M. Nagaraj, K. Usami, Z. Zhang, V. Görtz, J. W. Goodby and H. F. Gleeson, Liq. Cryst. (2014), 41, 800.
2M. Nagaraj, J. C. Nones, V. P. Panov, H. Liu, G. Portale, W. Bras and H. F. Gleeson, (2015) submitted.
3H. E. Milton, M. Nagaraj, S. Kaur, P. B. Morgan, J. C. Jones and H. F. Gleeson, Appl. Optics (2014), 53, 7278.
4M. Nagaraj, V. V. Görtz, J. W. Goodby and H. F. Gleeson, Appl. Phys. Lett. (2014), 104, 0219031
PI 4
From biaxiality to bistability, and back again.
J. Cliff Jones
School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
Having spent over thirteen years as C.T.O. of the spin-out company ZBD Displays that I had helped
found, I join academia to find a topic of great interest to me in my earlier career, biaxiality in liquid
crystal systems, has become important again. My early work, as George Gray’s last Ph.D. student in
Hull University, whilst working with Peter Raynes at R.S.R.E. in Malvern, had been on studying the
biaxial refractive indices and permittivities of the smectic C phase. Indeed, I showed that the large
dielectric biaxiality was responsible for the slowing of latching response times with increasing field
in surface stabilised ferroelectric liquid crystal devices. Understanding this led to major
breakthroughs in FLC for display applications, culminating in the demonstration of HDTV
performance in a passive matrix addressed display working with the Sharp Corporation in Japan and
Sharp Laboratories Europe in the mid-1990s.
In addition to biaxiality, FLC had the useful property of bistability where either of two states is
retained after an addressing pulse is applied allowing complex displays to be addressed line by line
without a thin-film-transistor at each pixel. Given the difficulties of obtaining and maintaining
uniform FLC alignment, an obvious approach was to induce bistability in a conventional nematic.
The only bistable nematic device to be commercialised is the zenithal bistable display or ZBD. This
uses deep homeotropic surface relief structures to induce both bistable states and a flexoelectric
polarisation. The commercial devices produced by the spin-out company ZBD Displays Ltd (now
Displaydata) latch in 500microseconds at 2Vm-1
. They are constructed at low cost using
embossing to form a bistable twisted nematic / hybrid nematic device. After perfecting the
manufacturing processes and developing a novel RF communication protocol, Displaydata has sold
millions of displays worldwide in electronic-shelf-edge labels for the retail sector.
Now in joint work with Helen Gleeson at Leeds and Mamatha Nagaraj at Manchester, my interest in
biaxiality has been re-ignited. In particular, the dark-conglomerate phase observed in certain bent-
core materials undergoes unusual changes in refractive index that are due to the biaxial nature of the
materials. As with the ferroelectric liquid crystals and the grating aligned nematics before them,
these phases have great potential for future device applicatons.
PI 5
Solid Liquid Crystals
Mark Warner Cavendish Laboratory, University of Cambridge, UK
Liquid crystals revolutionise both solid body mechanics and the seemingly impossible goal of
achieving Gaussian curvature from flat spaces.
SLCs arise from networks:
As elastomers, that is rubbers, where fluidity and director mobility are preserved
As glasses, that is strong solids where the director only “convects” with deformation.
Both types of solids lack positional order, but their LC anisotropy and possible complexity in
their director fields give unique phenomena in mechanics, topology and topography.
I 1
What does a Liquid Crystal Do in a Gyroid?
T J Athertona
aDepartment of Physics and Astronomy, Tufts University, Medford, MA 02155
Nematic liquid crystals in confined systems
adopt a distorted configuration to comply with
the surface anchoring conditions.
Compatibility between the symmetry of the
nematic order and the topology of the confined
system necessitates the introduction of defects;
the number and placement of these defects
must then be determined by energetic
considerations. A familiar example is that of a
nematic confined to lie tangentially to the
surface of a sphere: in this case, a total defect
charge of +2 is required to accommodate the
curvature by the Gauss-Bonnet theorem. The
ground state is found to be a tetrahedral
configuration of +1/2 defects.
Here, we study a related problem: what does a nematic do when confined to a gyroid
structure? The gyroid is a triply-periodic minimal surface that partitions space into two
disconnected regions. When one of the regions is filled with nematic liquid crystal, the
presence of curvature enforces the presence of defects and, intriguingly, the equilibrium
structures break chiral symmetry. We present our simulations of these structures—an example
is shown in the figure above—and study the effect of material and anchoring parameters on
the configurations obtained.
I 2
Myelin 19th century microscopy, giant squid (and a duel with Bismarck).
John Lydon Faculty of Biological Sciences,The University, Leeds, LS2 9JT [email protected]
Lipids have a variety of roles in biological systems. In all living organisms, phospholipid
bilayers form the membranes which encompass the cells (and the organelles within them), and
the ultimate food stores in animals are deposits of fat. Myelin, the white, lipid/protein mixture
which sheathes nerve fibres in higher animals, has a unique, and very different role to these. It is
an electric insulator, enhancing the speed at which impulses travel along nerve axons. For
completely myelinated axons the velocity can be as high as 12 m/sec. Without the myelin sheath
this would be reduced by factor of at least 10. In a world where response times can determine
survival rates, large animals would be at a severe evolutionary disadvantage without it. In
humans, depletion or damage to myelin layers can cause a variety of conditions, including
multiple sclerosis and schizophrenia.
When nerve tissue is placed in water it swells to a remarkable extent, producing ‘myelin figures’,
elongated finger-like growths which writhe like living material as they extend. This startling
phenomenon was first recorded in 1854, (34 years before Reinitzer’s cholesteryl esters) and is
arguably the first indication of liquid crystalline phases, [1, 2, 3]. This pioneering work took
place in Prussia at a time of great social upheaval and intense political activity. One of foremost
workers irritated the government with his liberal views to the extent that he found himself
challenged to a duel by the Iron Chancellor himself [4]. Interesting times indeed.
References
[1] R. Virchow, Über das ausgebreitete Vorkommen einer dem Nervenmark analogen Substanz in den
tierischen Geweben, (On the widespread distribution in animal tissues of a substance analogous to
nerve marrow), Virchows Arch. Pathol. Anat.) 1854, 6 (4): 562–72. doi:10.1007/BF02116709
[2] O. Lehmann, Über Contactbewegung und Myelinformer (On contact motion and myelin
formation), 1895, Weidemann’s Annalen fur Physik und Chemie 56, 771-788.
[3] D. Dunmur and T. Slukin, Soap, science and flat screen TVs - a history of liquid crystals, Oxford
University Press, 2011, pages 124, 130 134, 280 293.
[4] G.A.Silver, (1987). "Virchow, the heroic model in medicine: health policy by accolade". American
Journal of Public Health 77 (1): 82–88. doi:10.2105/AJPH.77.1.82. PMC 1646803. PMID 3538915.
Exterior
rs
ro ro
Interior
ri ri
rn rn
T 1
Colloids in Blue Phase Liquid Crystals
A.C. Pawseya,b
,Paul. S. Clegga
aSUPA, School of Physics and Astronomy, JCMB, Peter Guthrie Tait Road EH9 3FD, Edinburgh, UK bRowett Institute of Nutrition and Health, Greenburn Road,Bucksburn, Aberdeen, AB21 9SB, UK
Colloid–liquid crystal composites are an exciting class of responsive, soft materials. Colloidal
particles mixed into liquid crystals create defects in the (ideally defect free) ordered phase.
The form of the defects is dependent on the particle size, the alignment of the mesogens at the
particle surface and how strongly this alignment is enforced (the anchoring strength).
Highly chiral LCs have delicate phases formed from an ordered arrangement of defect lines.
These cholesteric blue phases normally only appear in a narrow window of temperature and
chirality due to the delicate balance between satisfying an increased degree of twist with the
expense of creating defect lines.
We add micron-sized colloids to a chiral nematic LC with a blue phase as a means to study
the effect of disorder on the phase transitions of a system already dominated by defects. The
colloids are a source of disorder, disrupting the liquid crystal as the system is heated from the
cholesteric to the isotropic phase through the blue phase. The colloids act as a preferential site
for the growth of BPI from the cholesteric; in high chirality samples BPII also forms. In both
BPI and BPII the colloids lead to localised melting to the isotropic, giving rise to faceted
isotropic inclusions. This is in contrast to the behaviour of a cholesteric LC where colloids
lead to system spanning defects.
References:
1) A. C. Pawsey, P. S. Clegg, (2015) Soft Matter DOI: 10.1039/c4sm02131b
T 2
Computer simulations of an anionic chromonic dye: spontaneous symmetry
breaking to form chiral aggregates and the formation of a novel smectic phase
omnik Thind1, Mark R. Wilson
1
1Department of Chemistry, Durham University, Durham, DH1 3LE, UK
Corresponding author e-mail: [email protected]
Controlling self-assembly of nanostructured soft matter
in aqueous solution is of considerable interest in the
formation of thin organic films and in future organic
electronics applications. Interpretation of experimental
findings for the anionic chromonic dye (figure 1), has lead
to the proposal of two self-assembled structures not
typically observed for chromonic systems, with a double-
width column arrangement for the nematic region, and the
transition to a non-columnar layer structure at higher
concentrations. The deviation of these proposed models
from the more common behaviour of chromonic
mesogens, to favour a direct face-to-face aromatic
stacking to form columns, has to lead to speculation as to
how energetically feasible these more rare motifs are.
Molecular dynamics simulations at a fully atomistic level are able to
provide a “picture” of the preferred stacking structure within
chromonic aggregates in aqueous solution [1]. A new interpretation
for experimental results is provided, with low concentrations of the
anionic dye (figure 1) showing spontaneous symmetry breaking,
wherein chiral aggregates (figure 2) form as the energetically most
stable species. This is despite the presence of a strictly achiral dye
mesogen.
Results for higher concentrations show the alignment of several
aggregates to form a novel biaxial-smectic layer structure, with the
inherent loss of chirality as a result of this new molecular
environment. The formation of the novel layer structure, which is
stabilized by interactions of surface charged groups explains key
experimental findings, as well as retaining the more common
columnar stacking found in typical chromonic systems.
Summary: Atomistic molecular dynamics simulations have provided evidence for:
(i) the spontaneous self-assembly of achiral molecules in solution to form chiral aggregates,
(ii) a novel biaxial-smectic chromonic phase not seen previously.
References
[1] F. Chami and M. R. Wilson, J. Am. Chem. Soc., 132, 7794-7802 (2010)
Figure 1: Structure of an anionic
chromonic dye
Figure 2: Chiral aggregates
of an anionic dye
T 3
Design and investigation of a gold nanoparticle side-chain liquid crystal polymer
nanocomposite
O. Amos and G. H. Mehl
Department of Chemistry, University of Hull, HU6 7RX, UK
Metal nanoparticle functionalized liquid crystalline materials have attracted considerable attention
due to their potential applications in magnetic, optical, electronic devices and as catalysts. The
optical and magnetic properties of these nanoparticles are of high interest and this related to the
potential of 2D and 3D organisation of such materials. Research on the organic groups for such
systems has concentrated mainly on the type of the mesogenic groups selected and to some extend
on the functional groups linking the NPs and the mesogens1,2
. A parameter which has been
investigated in less detail, with the notable exception of some dendritic mesogens3,4
is the size of
the organic corona.
Here we present our results on the investigation of gold NPs where side-chain LC polymer chains
(SCLCPs) have been attached to the NPs. The synthesis of these systems was explored
systematically. The length of the chains and the number of mesogenic groups were varied
systematically. The preparation of SCLCPs, either by grafting to the NPs or by polymerisation
from the preparation of an Au-NP macroinitiator were explored. The mode of polymerisation either
free radical polymerisation or atom transfer radical polymerisation (ATRP) was varied5-9
.
The results of the synthetic work will be presented and the chemical characterisation by NMR. GPC
and MALDI-TOF and TEM of the AuNP-SCLCP nanocomposites will be reported. The results of
the investigations of the LC properties of these systems, based on OPM, DSC and XRD
investigations will be presented. The properties of these systems will be discussed and will be
compared to structurally related materials.
References
1. S. Umadevi, X. Feng and T. Hegmann, Adv. Funct. Mater. 2013, 23, 1393-1403
2. M. Mojcik, W. Lewandowski, J. Matraszek, J. Mieczkowski, j. Borysiuk, D. Pociecha, E. Gorecka, Angew. Chem. Int. Ed. 2009, 48,
5167-5169
3. B. Donnio, P. G. Vázquez, J. L. Gallani, D. Guillon, and E. Terazzi, Adv. Mater. 2007, 19, 3534–3539
4. K. Kanie, M. Matsubara, X. B. Zeng, F. Liu, G. Ungar, H. Nakamura and Muramatsu, J. Am. Chem. Soc., 2012, 134, 808-811
5. W. A. Braunecker, K. Matyjaszewsi, Prog. Polm. Sci., 2007, 32, 93-146
6. N. J. Warren, C. Muise, A. Stephens, S. P. Armes, and A. L. Lewis Langmuir, 2012, 28 (5), 2928–2936
7. K. Matsura, K. Ohno, S. Kagaya, H. Kitano, Macromol. Chem. Phys., 2007, 208, 862-873
8. A. D’Annibale, L. Ciaralli, M. Basseti, C. J. Pasquini, J. Org. Chem., 2007, 72, 6067–6074
9. G. Hughes, M. Kimura, S. L. Buchwald, J. Am. Chem. Soc., 2003, 125,11253-11258
T 4
A combined experimental and computational study of anthraquinone dyes
as guests within nematic liquid crystal hosts
M. T. Sims, L. C. Abbott, S. J. Cowling, J. W. Goodby, and J. N. Moore
Department of Chemistry, The University of York, Heslington, York, YO10 5DD, UK
The use of dye molecules within liquid crystal hosts has been studied in the past for a wide
variety of different dyes and host mixtures, and explored for the development of a range of
practical devices. The potential applications of such systems are widespread, with the focus
often being on guest-host display devices, and they may offer benefits over traditional liquid
crystal displays.
For guest-host applications, the alignment of guest dye molecules within a liquid crystal host
is important for the development of practical devices, and other factors such as the dye colour,
absorption strength, and stability also need to be considered. Hence, it is desirable to obtain a
detailed knowledge of the structure and properties of dye molecules proposed for such
applications, and to rationalise their behaviour in liquid crystal hosts.
We have been studying anthraquinone dyes with a range of colours, including some
phenylamine and phenylsulfide disubstituted systems drawn from a class which have been
relatively widely studied, as well as some recently synthesised directly arylated systems.1
Our UV-visible absorption studies of these dyes in the
nematic host mixture E7 have provided experimental
dichroic ratios of the dyes, which give significant
differences in their observed order parameters. We
have also been carrying out computational studies,
including density functional theory calculations on
the dyes, yielding insights into the basis of the
observed differences in colour and the natures of the
electronic transitions giving rise to their visible
absorption bands. Fully atomistic molecular dynamics
simulations of the guest-host systems have enabled
the molecular alignments within the host to be
assessed, and, in combination with the DFT
calculations, have provided a direct comparison with
the experimental dichroic ratios.
References
1. S. J. Cowling, C. Ellis, and J. W. Goodby, Liquid Crystals, 38: 1683–1698 (2011).
T 5
0 16 32 0 16 32
z [µm] z [µm]
(π/2
− θ
) [r
ad]
(π/2
− θ
) [r
ad]
Multiscale models of metallic inclusions in nematic
liquid crystals
T.P. Bennetta , G. D’Alessandroa K.R. Dalyb a Mathematical Sciences, University of Southampton, Southampton, England, UK b Engineering Sciences, University of Southampton, Southampton, England, UK
Suspension of nanoparticles in liquid crystals have been modelled on a range of scales, from molecular
simulations [2] to macroscopic models [3]. The former are computationally expensive and only a few particles
can be modelled. The second rely on macroscopic parameters whose values are not determined self-consistently. In previous work [1] we have derived equations governing a nematic liquid crystal hosting fixed metallic
inclusions with weak anchoring conditions. In this case we obtained macroscopic governing equations containing
effective material parameters that are related to the microscopic geometry by a series of cell problems. These
describe the local effect of a single nanoparticle on the liquid crystal alignment and electric field based on the
assumption that the nanoparticles are evenly distributed and, hence, the underlying geometry is approximately
periodic. We obtain good agreement between finite element simulations of a planar cell containing ellipsoidal
inclusions and our macroscopic model as shown in figure 1. In the weakly interacting regime, i.e.
small anchoring energy and/or low concen-
trations, the liquid crystal director is de-
termined by a balance between the bulk
forces in the liquid crystal and the align-
ment at the boundary of the device and
at the nanoparticles. In this regime,
the macroscopic equations for the direc-
tor alignment contain three key differences
with respect to those for a pure liquid crys-
tal: (i) the elastic constants are in general
smaller, (ii) there is a forcing term pro-
portional to the anisotropy of the parti-
2 (a)
1 0
1 0.5
0
(b)
cles and, (iii) the dielectric susceptibility
of the system is altered due to the fringe
fields created by the metallic particles. We are in the process of extending this
work to include particles that are free to
rotate. The motion of the particles and ne-
matic is modelled using a dissipation prin-
ciple [4]. We discuss the derivation of the
Figure 1: Verification of our model for a 32 cell system, each cell con-
tains a single ideal metallic particle. Red points are from homogeniza-
tion, broken black line corresponds to a pure liquid crystal, and blue line
is from COMSOL finite element simulations. Left panel shows spherical
particles of radius r = 0.3 µm at 1.5 and 3 Volts. Right panel ellipsoidal
particles with semi axes 0.1 and 0.3 µm at zero applied field for different
anchoring energies.
equations, provide an interpretation of the terms driving the reorientation of the particles and discuss how this
approach can be used to study the effects of freely rotating particles on the dynamics of the liquid crystal. For
example the effective anisotropic fields induced by the particles become time dependent.
References
[1] T. P. Bennett, G. D’Alessandro, and K. R. Daly, Multiscale models of colloidal dispersion of particles
in nematic liquid crystals, Phys. Rev. E, 90 (2014), p. 062505.
[2] B. T. Gettelfinger, J. A. Moreno-Razo, G. M. Koenig Jr, J. P. Hernandez-Ortiz, N. L. Abbott, and J. J. de Pablo, Flow induced deformation of defects around nanoparticles and nanodroplets
suspended in liquid crystals, Soft Matter, 6 (2010), pp. 896–901.
[3] L. M. Lopatina and J. V. Selinger, Theory of Ferroelectric Nanoparticles in Nematic Liquid Crystals,
Phys. Rev. Lett., 102 (2009), p. 197802.
[4] A. Sonnet, P. Maffettone, and E. Virga, Continuum theory for nematic liquid crystals with tensorial
order, J. Non-Newtonian Fluid Mech., 119 (2004), pp. 51 – 59.
T 6
Further tricritical and antinematic behaviour
in a revisited mildly repulsive Straley model
F. Bisia , G. De Matteis
b and S. Romano
c
aDipartimento di Matematica “F. Casorati”, Università di Pavia, via A. Ferrata, 1, 27100 Pavia, Italy
bDepartment of Mathematics and Information Sciences, Northumbria University, Camden Street, NE2 1XE, UK
cDipartimento di Fisica “A. Volta”, Università di Pavia, via A. Bassi 6, 27100 Pavia, Italy
We consider biaxial nematogenic lattice models, involving particles of D2h symmetry, whose
centres of mass are associated with a three–dimensional simple-cubic lattice. The pair potential is
isotropic in orientation space and restricted to nearest neighbours. Let two orthonormal vector triads
define orientations of a pair of interacting particles. The investigated potential models are quadratic
with respect to the nine scalar products between the two sets of unit vectors. Available geometric
duality transformations allow to reduce these expressions to diagonal form containing only the
scalar products between corresponding unit vectors and depending on three coupling constants. The
resulting potential is known in the literature as the generalised Straley model. By now, various sets
of values of the free model parameters have been studied and they are capable of producing both
calamitic and antinematic phases, both biaxial and uniaxial phases, both first– and second–order
phase transitions. Here, we further pursue the analysis in terms of a molecular-field approach and a
Monte Carlo simulation study of a family of potential models, namely the μ models, put forward in
[1]. In these models, two predominant calamitic couplings of equal strength (−2) are perturbed by a
comparatively weaker antinematic one, parameterised by a coupling constant 1+μ, where μ ranges
in [0, 1].
It has been shown in [1] that for μ sufficiently small the model predicts second–order transitions to
the biaxial nematic phase from both the isotropic and the uniaxial phases. The models, further
explored here, unveil first–order transitions from the uniaxial to the biaxial phase, thus disclosing a
tricritical behaviour. The change of order sets in at values of μ close to 1 where the antinematic
coupling constant become comparable with the calamitic ones.
An adapted Monte Carlo computational procedure allowed differentiating between ordering of the
three molecular axes, the ones calamitically and the ones antinematically coupled, so to speak, and
to detect a change in the order of transition from the uniaxial to the biaxial phase in the low
temperature regime. On the other hand, a molecular–field approach in the asymptotic regime (μ
approaching 1) has confirmed the same tricritical behaviour.
References
[1]G. De Matteis and S. Romano, Phys. Rev. E 78, 021702 (2008).
T 7
Origin of Chirality in the Triple Network Tri-continuous Cubic Phase
Formed by Achiral Rod-like Molecules
X. B. Zenga, G. Ungar
a, F. Liu
b, C. Dressel
c, M. Prehm
c and C. Tschierske
c
aDepartment of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, UK
b State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, P. R. China c Institute of Chemistry, Organic Chemistry, Martin-Luther-University Halle-Wittenberg, 06120 Halle, Germany
Two cubic phases, formed by infinite
interpenetrating molecular networks, have been
known in thermotropic liquid crystals for years.
They are the “double gyroid” phase with two
networks (symmetry Ia3d), and the “triple
network” phase with three networks (symmetry
Im3m)1. However, it has only been discovered
recently by polarized optical microscopy and CD
spectroscopy that, despite being formed from
achiral rod-like molecules, the triple-network
cubic phase (Im3m) is always chiral, while the
double-network (Ia3d) phase is always achiral2.
These intriguing observations are explained by
propagation of homochiral helical twist across
the entire network through helix matching at
network junctions. In the Ia3d phase the
opposing chiralities of the two networks cancel,
but not so in the triple-network Im3m phase
(Figure 1). The high twist in the Im3m phase
explains its previously unrecognized chirality, as
well as the origin of this complex structure and
the transitions between different cubic phases.
Figure 1. (a) The two networks (red and blue) of the Ia3d phase decorated with schematic mesogens (rod-
like molecular cores, green) showing the molecular twist along the network segments. The gyroid minimum
surface is also shown (yellow). (b) The same but for the middle of the three networks of the Im3m
phase .This network closely follows the Schwartz P-type minimum surface (shown in yellow). (c) The middle
network shown as ribbons containing the molecular axes (black rods). (d-f) Detailed network junctions in
ribbon representation for the Im3m phase.
References 1 X. B. Zeng, G. Ungar and M. Imperor-Clerc, Nat. Mater. (2005), 4, 562 – 567.
2 C. Dressel, F. Liu, M. Prehm, X. B. Zeng, G. Ungar and C. Tschierske, Angew. Chem. Int. Ed. (2014), 53, 1 – 7.
i
d
c b
a
f
h j
e
g
I II
T 8
Coarse Grained Modelling of the Phase Behaviour and Structure of Non-Ionic
Surfactants with the SAFT- force field O. Lobanova, C. Herdes, E. A. Müller, and G. Jackson
Department of Chemical Engineering, Centre for Process Systems Engineering, South
Kensington campus, Imperial College London, London SW7 2AZ, United Kingdom
An application of the “top-down” concept for the development of accurate coarse-grained
intermolecular potentials of complex fluids from an algebraic equation of state is used in the context
of aqueous solutions of non-ionic surfactants. In our approach, we use a recent implementation of
the statistical associating fluid theory of variable range (SAFT-VR) [1], and its group-contribution
formulation (SAFT- to develop effective coarse-grained force fields based on the Mie
(generalised Lennard- Jones) potential. Fluid-phase equilibrium properties such as the vapour
pressure and saturated liquid density are used to efficiently estimate the parameters of the coarse-
grained Mie force field over a broad range of thermodynamic conditions with the aid of the
algebraic equation of state [3]. The
SAFT-γ coarse-grained models can then
be used in direct molecular simulation to
describe properties which were not used
to develop the potential model such as
the enthalpy of vaporisation, interfacial
tension, density profiles, supercritical
densities, and other thermodynamic,
structural, and transport properties. The
versatility of the procedure has been
demonstrated for carbon dioxide (CO2)
[4] and other green-house gases [5], n-alkanes [5], alkylbenzenes [6], and water [7]. Here we
develop a generic CG force field for aqueous solutions of alkylpolyoxyethylene (CiEj) non-ionic
surfactants. Although the parameterisation for the different chemical moieties is carried out to
match the thermodynamic bulk properties of representative compounds (alkanes, alkyl ethers,
gylcols), the SAFT-γ force field is found to be robust and transferable allowing for the prediction of
the key structural, interfacial and kinetic properties of the surfactant solution. The spontaneous
formation of micelles at low surfactant concentrations is observed as well as expected self-assembly
into bilayer at high surfactant concentrations. Members of the CiEj family of varying alkyl and
ethoxy chain length are investigated to assess the transferability of the model. The aggregation
numbers, critical micelle concentrations, as well as surfactant area and bilayer thickness are found
in a good agreement with experimental data.
References [1] T. Lafitte, A. Apostolakou, C. Avendaño, A. Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013).
[2] V. Papaioannou, T. Lafitte, C. Avendaño, C. S. Adjiman, G. Jackson, E. A. Müller, and A. Galindo, J. Chem. Phys.140, 054107 (2014).
[3] E. A. Müller and G. Jackson, Ann. Rev. Chem. Biomol. Eng. 5, 405 (2014).
[4] C. Avendaño, T. Lafitte, A. Galindo, C. S. Adjiman, G. Jackson, and E. A. Müller, J. Phys. Chem. B 115, 11154 (2011).
[5] C. Avendaño, T. Lafitte, C. S. Adjiman, A. Galindo, E. A. Müller, and G. Jackson, J. Phys. Chem. B 117, 2717 (2013).
[6] T. Lafitte, C. Avendaño, V. Papaioannou, A. Galindo, C. S. Adjiman, G. Jackson, and E. A. Müller, Mol. Phys. 110, 1189 (2012).
[8] O. Lobanova, C. Avendaño, E. A. Müller, and G. Jackson, Mol. Phys. (2015) DOI:10.1080/00268976.2015.1004804 (2015).
T 9
Synthesis and properties of asymmetric dimeric materials with lateral and
terminal fluorine substituents for dual frequency liquid crystal mixtures
David Allan and M. Hird
Department of Chemistry, University of Hull, Hull HU6 7RX, UK
Nematic liquid crystals have been widely used in electro-optical devices due to the ability to switch
the orientation of materials using an external electric field. In conventional device, while the switch-
on response time can be decreased by increasing the electric field, the switch-off relaxation process
is much slower.[1]
With the continuing requirement for faster switching times and alternative route can be found in
dual frequency liquid crystal materials (DFLCs). Usually DFLC materials are a two component
mixture, positive compounds with a positive dielectric anisotropy that decreases at higher
frequencies and negative compounds with a large negative dielectric anisotropy that remains almost
constant across different frequencies.[1]
A liquid crystal dimer is a material with two mesogenic core units separated by a flexible spacer,
usually alkyl chains. Dimers have been the target of a great deal of research due to the unusual
liquid crystal behaviour they exhibit.[2]
A series of asymmetric dimeric materials have been targeted, these feature one core unit with lateral
fluorine substituents and the other core with terminal fluorination. The aim is to synthesise
materials with one core contributing to positive dielectric anisotropy and the other negative
dielectric anisotropy. The synthesis of a series of fluorinated dimers is described. With the
mesomorphic properties characterised by OPM, DSC and XRD.
References: [1] H. Xianyu, S.-T. Wu, and C.-L. Lin, Liquid Crystals, 2009, 36, 717–726.
[2] C. T. Imrie and P. A. Henderson, Curr. Opin. Colloid Interface Sci., 2002.
T 10
Liquid crystal dimers: A molecular level and mesoscale study
Martin Walker and Mark Wilson*
Department of Chemistry, Durham University, Durham, DH1 3LE, UK
Liquid crystal dimer molecules exhibit a puzzling, and as yet, not fully characterised phase
transition between the nematic and smectic phases. This new phase was originally denoted
the Nx phase to highlight its unknown nature. The Nx phase is commonly interpreted using
one of two theories: that the phase is a twist-bend nematic NTB (where the nematic director
both twists and bends, resulting in a helical director structure with a singular nematic order
parameter), or a pre-transitional cybotactic nematic (where small, unaligned smectic domains
give rise to an overall (biaxial) nematic order parameter).
To help elucidate the structure of the Nx phase, we have simulated liquid crystal dimer
molecules using a coarse-grained methodology, which allows a large number of dimer
molecules to be studied (105 molecules) for the first time.
We have found both a stable nematic and smectic phase. Between these two well established
phases we find another stable mesophase that is neither nematic nor smectic, but maintains
features of both phases. In this “Nx phase”, the bent nature of the dimer molecule imposes a
small bend between layers that are otherwise locally smectic. This removes any long range
ordering of layers. This behaviour can only be seen in large simulations, where we are able
to look at more than the local order seen in previous small atomistic simulations [1], and
analyse molecular order in more depth.
[1] Chiral heliconical ground state of nanoscale pitch in a nematic liquid crystal of achiral
molecular dimers, D. Chen, J. H. Porada, J. B. Hooper, A. Klittnick, Y. Shen, M. R.
Tuchband, E. Korblova, D. Bedrov, D.M. Walba, M. A. Glaser, J. E. Maclennan, and N.A.
Clark, Proc. Nat. Acad. Sci., 2013, 110, 15931–15936.
Nx
T 11
Raman scattering studies of orientational order parameters in liquid
crystalline dimers exhibiting conventional and twist-bend nematic phases
Vitaly P. Panov,a Zhaopeng Zhang,
a , Mamatha Nagaraj,
a Richard J. Mandle,
d John W.
Goodby,d Geoffrey R. Luckhurst,
c J. Cliff Jones
a,b and Helen F. Gleeson
a,b
aSchool of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
bSchool of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK cChemistry, University of Southampton, Highfield, Southampton SO171BJ, UK
dDepartment of Chemistry, University of York, York YO10 5DD, UK
Liquid crystalline dimers have recently attracted significant attention due to the intriguing
properties of the twist-bend nematic phase (NTB), discovered in dimers with an odd number
of carbon atoms in the linking alkyl chain1,2,3
. Understanding both the physical properties of
the twist-bend phase and its relationship to the conventional nematic phase (N) is of
significant interest. We have used Polarised Raman Spectroscopy (PRS) to quantify the
orientational order in both of the nematic phases that occur in certain liquid crystalline dimers.
PRS is a particularly powerful way of determining order parameters as both ⟨𝑃2⟩ and ⟨𝑃4⟩ order parameters can be determined
4
A series of compounds has been investigated
with alkyl chain lengths of 7, 8, 9 and 11
carbons connecting two cyanobiphenyl
mesogenic groups. The nature of the Raman
spectra has been investigated across the
temperature range, including the N and NTB
phases, where it was found that the Raman
peaks do not show a significant change in
wavenumber, even across the NTB-N phase
transition. Both ⟨P2⟩ and ⟨𝑃4⟩ order parameters
have been determined across the N phase
range. Measurements were also made into the
NTB phase just below the NTB - N phase transition where a uniform NTB texture can be
maintained. In the N phase, the odd dimers exhibit rather low order parameters with ⟨𝑃2⟩ taking values between 0.3 and 0.5 and ⟨𝑃4⟩ about 0.25, in keeping with their bent shape. In
contrast, the even dimer shows extremely high values of the order parameters with ⟨𝑃2⟩ between 0.7 and 0.8 and ⟨𝑃4⟩ between 0.4 and 0.45. For the odd dimers, the values of ⟨𝑃2⟩ in
the NTB phase are similar to those of the N phase, while ⟨𝑃4⟩ jumps by approximately 5-10%
and changes its temperature dependence. On comparing the results with the predictions of a
molecular field model, we find good agreement for the elongated molecules of the even
dimer. The odd dimers, however, show higher ⟨𝑃4⟩ values than that obtained from the model,
also as might be expected for molecules having predominantly bent conformations.
1 M. Šepelj, A. Lesac, U. Baumeister, S. Diele, H. L. Nguyen and D. W. Bruce, J. Mater. Chem., 2007, 17, 1154.
2 V. P. Panov, M. Nagaraj, J. K. Vij, Y. P. Panarin, A. Kohlmeier, M. G. Tamba, R. A. Lewis and G. H. Mehl,
Phys. Rev. Lett., 2010, 105, 16780. 3 M. Cestari, S. Diez-Berart, D. A. Dunmur, A. Ferrarini, M. R. de la Fuente, D. J. B. Jackson, D. O. Lopez, G.
R. Luckhurst, M. A. Perez-Jubindo, R. M. Richardson, J. Salud, B. A. Timimi and H. Zimmermann, Phys. Rev.
E, 2011, 84, 031704. 4 C D. Southern and H. F. Gleeson, Eur. Phys. J. E 2007, 24, 119.
7 8 9 10 110.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
8CB
T/T
NI=
0.9
80
T/T
NI=
0.9
80
T/T
NI=
0.9
82
T/T
NI=
0.9
84
T/T
NI=
0.9
81
Ord
er
Para
mete
rs
n value for CB-Cn-CB
T/T
NI=
0.9
82
5CB
T 12
Complex Rheology of Nematogenic Fluid; Connection to Elastic Turbulence
B. Chakrabarti, R. Mandal, D. Chakraborty, and C. Dasgupta
Department of Mathematical Sciences, Durham University, Durham, DH1 3lE, UK
Rheological chaos and Elastic turbulence are two phenomena that have attracted a lot of attention in
recent years. Motivated by experiments that probe statistical quantities of these two phenomena
we numerically analyse the full non-linear hydrodynamic equations of a sheared nematic fluid
under shear stress and strain rate controlled situations incorporating spatial heterogeneity in the
gradient direction. For a certain range of imposed stress and strain rates, this extended dynamical
system shows signatures of spatio-temporal chaos and transient shear banding. In the chaotic regime
the power spectra of the order parameter stress and the total injected power shows power law
behavior and the total injected power shows a non-Gaussian, skewed probability distribution, which
bear striking resemblance to elastic turbulence phenomena observed in polymer solutions. The
scaling behavior is independent of the choice of shear rate/stress control method.
References
[1] Chakrabarti, B, Das, M, Dasgupta, C, Ramaswamy, S & Sood, AK (2004). Spatiotemporal
rheochaos in nematic hydrodynamics. Physical Review Letters 92(5).
[2] Das, M, Chakrabarti, B, Dasgupta, C, Ramaswamy, S & Sood, AK (2005). Routes to
spatiotemporal chaos in the rheology of nematogenic fluids. Physical Review E 71(2).
[3] Mandal, R., Chakrabarti, B., Chakraborty, D. & Dasgupta, C. (2014). Complex Rheology of
Nematogenic Fluid; Connection to Elastic Turbulence.
http://arxiv-web3.library.cornell.edu/pdf/1406.2575v1.pdf
T 13
Interfacial motion by mean curvature in liquid crystals
Amy Spicera, and Apala Majumdar
a
aMathematical Sciences, University of Bath, Bath, BA1 2BL, UK
Nematic liquid crystals are anisotropic orientationally ordered liquids. Working within the Landau-
de Gennes theoretical framework, equilibrium nematic configurations are modelled by local or
global minimisers of the corresponding Landau-de Gennes energy functional. We adopt the
gradient-flow model for dissipative Landau-de Gennes dynamics to study the creation and evolution
of nematic-isotropic interfaces in a cylinder, at the nematic-isotropic transition temperature. We
impose Dirichlet radial conditions on the lateral surface and numerically study the full parabolic
gradient flow system for the Landau-de Gennes Q-tensor in three dimensions, differentiating
between planar and non-planar initial conditions with a nematic-isotropic interface structure.
Solutions with planar initial conditions retain the nematic-isotropic interface at all times and
converge to a uniaxial radial solution with a localized isotropic core around the cylinder axis.
Solutions with non-planar initial conditions lose the interface after finite time and converge to an
almost uniaxial solution of constant norm.
References
1 L. Bronsard, R. Kohn, Motion by mean curvature as the singular limit of Ginzburg Landau dynamics, Journal of differential equations (1991), 211,
237
2 L. Bronsard, B. Stoth, On the existence of high multiplicity interfaces, Mathematical research letters (1996), 41, 50
3 F. Bethel, H. Brezis, B. Coleman, F. Helein, Bifurcation analysis of minimizing harmonic maps describing the equilibrium of nematic phases
between cylinders, Archive for rational mechanics and analysis (1992), 149, 68
T 14
A computationally efficient Q-tensor model with flow for nematic
liquid crystals
Murugesan Y.K
a, D’Alessandro G
a, De Matteis G
b
aMathematical Sciences, University of Southampton, Southampton, England, UK;
bDepartment of Mathematics and Information Sciences, Northumbria University, Newcastle Upon
Tyne, England, UK.
Modelling liquid crystalline flows play a vital role in understanding the non-
equilibrium dynamics in active synthetic and biological soft matter systems1 and
switching dynamics in liquid crystal based electro-optical devices2. We present a new,
computationally efficient method to model the coupled dynamics of flow and
alignment of nematic liquid crystals in the absence of defects.
Traditionally, there are two approaches to model liquid crystal alignment with flow.
In the Ericksen-Leslie formalism3 the director field is represented with a unit vector n
and the alignment dynamics of the director is coupled to the velocity field of the fluid
flow. The equations for this vector representation have only one time constant and are,
hence, computationally efficient. Alternatively, Sonnet et al4 represent the director
field using a 33 traceless, symmetric tensor, the Q-tensor, and obtain the alignment
and fluid flow equations from the most generic dissipation function that satisfies the
symmetries of the system. This tensor formalism can represent without ambiguity any
alignment and embodies the nematic symmetry automatically. Moreover, it takes into
account the orientational order of the liquid crystal by including the thermotropic
energy in addition to the elastic counterpart. However, due to the difference in
magnitudes of the two energy contributions away from a topological defect, the
corresponding dynamical equations for the director alignment have two considerably
different time scales: the resulting computational model is, hence, very stiff and hard
to compute efficiently.
In this talk, we combine the Q-tensor with flow equations of Sonnet et al4 with the
multiple time scale approach developed by Daly et al5
and obtain a computationally
efficient, one-time-scale model for the orientation of the liquid crystal in the absence
of defects. As a validation of our derivation we compare our results with the Ericksen-
Leslie theory for 1D planar and twisted nematic cells3 and present numerical
simulation of coupled flow and alignment in representative nematic cells.
References 1M. Ravnik and J.M. Yeomans, Phys. Rev. Lett. (2013), 110, 026001.
2A. Tiribocchi, O. Henrich, J.S. Lintuvuori and D. Marenduzzo, Soft Matter, (2014),
26, 4580. 3M.G. Clark and F.M. Leslie, Proc. R. Soc. Lond. A. (1978), 361, 463.
4A.M. Sonnet, P.L. Maffettone, and E.G. Virga, J. Non-Newtonian Fluid Mech.
(2004), 119, 51. 5K.R. Daly, G. D’Alessandro, and M. Kaczmarek, SIAM J. Appl. Math. (2010), 70,
2844.
T 15
Rheology of Cholesteric Liquid Crystalline Phases
O. Henricha , K. Stratford
a , M.E. Cates
b and D. Marenduzzo
b
aEdinburgh Parallel Computing Centre, University of Edinburgh, Edinburgh EH9 3FD, UK
bSchool of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
The flow response in cholesterics is strongly non-Newtonian, highly anisotropic and complex.
Theoretical studies showed that a standard cholesteric phase subjected to Poiseuille flow along its
helical axis flows mainly through permeation at small pressure differences, leading to high
dissipation and very large viscosities. If the helix is oriented along the vorticity direction travelling
twist waves appear which cause a rotation of the cholesteric helix. Under higher forcing, the helix
uncoils, creating a flow-induced nematic phase. Most of these pioneering results have been derived
under specific assumptions like the absence of defects or the constraint that the molecules may only
rotate in the flow-gradient plane whilst the orientation of the cholesteric helix remains unchanged 1,2
.
Building on our expertise in large-scale simulation of liquid crystals we are able to investigate more
general situations. We present new results on the flow of cholesteric fingers and blue phases in
microfluidic channels. Depending on the pressure gradient between inlet and outlet, the geometry
and anchoring conditions at the channel walls we are able to characterise different flow regimes.
These results add to the complex picture that we previously gained from cubic blue phases in simple
shear flow3
and contribute to an understanding of the complex flow behaviour of cholesteric phases.
Figure 1: Secondary flow pattern of Blue Phase I in simple shear flow
References 1
A.D. Rey, J. Rheol. (2000), 44, 855. 2
A.D. Rey, J. Rheol. (2002), 46, 225. 3O. Henrich, K. Stratford, P.V. Coveney, M.E. Cates, D. Marenduzzo, Soft Matter (2013), 9, 10243.
T 16
Anisotropic Dielectrophoresis – Nematic Liquid Crystals
A. Saxena*,1
C. Tsakonas,1
I.C. Sage,1 G. McKay,
2 N.J. Mottram,
2 R.P. Tuffin,
3 C.V. Brown
1
1 School of Science and Technology, Nottingham Trent University,
Clifton Lane, Nottingham NG11 8NS, United Kingdom
2 Department of Mathematics and Statistics, University of Strathclyde,
Livingstone Tower, 26 Richmond Street, Glasgow G1 1XH, United Kingdom
3 Merck Chemicals Ltd, University Parkway, Chilworth, Southampton,
Hampshire SO16 7QD, United Kingdom
Liquid dielectrophoresis describes the phenomenon by which dielectric liquids move to
occupy regions of high electric field in response to forces on the electric dipoles in the liquid
created by regions of high gradient in the electric field magnitude[1]
. Applications that exploit
liquid dielectrophoresis effects include switchable microlenses, optical shutters, beamsteerers
and diffraction gratings, and electronic paper displays and micro pumps[2,3]
.
Nematic liquid crystals are attractive for many of these applications because they are often
designed to exhibit high permittivity, which provides a high driving force for
dielectrophoresis[2]
. This is combined with other favourable properties including high
refractive index, useful for switchable refractive/diffractive optics applications, plus stability
and relatively low viscosity.
In a moving nematic liquid crystal film the local orientation of the molecular n-director is
determined by balance of torques arising from the direction and magnitude of the applied
electric fields, the local flow direction, and the elastic coupling transmitted from any surface
anchoring. Since the material is anisotropic the orientation of the n-director in turn influences
the magnitude of the dielectrophoresis forces and the rate of viscous flow and spreading. We
have investigated the coupling between these effects during the spreading and actuation of
nematic liquid crystal materials. A number of model geometries have been developed and
used that allow key simplifications to be made in the theoretical analysis, which includes co-
planar electrode arrangements.
We acknowledge funding from the UK EPSRC (EP/J009865/1 and EP/J009873/1) and Merck
Chemicals Ltd.
References:
[1] T.B. Jones, Hydrostatics and steady dynamics of spatially varying electromechanical flow
structures, J. Appl. Phys. 45, 1487–1491 (1974).
[2] S. Xu, H. Ren, and S-T. Wu, Topical Review Dielectrophoretically tunable optofluidic
devices, J. Phys. D: Appl. Phys. 46, 483001–483014 (2013).
[3] C.V. Brown, G.G. Wells, M.I. Newton, and G. McHale, Voltage-programmable liquid
optical interface, Nature Photonics 3, 403–405 (2009).
_____________________________________________
* presenting author; E-mail: [email protected]
T 17
Bleaching wave dynamics in photobending
Chen Xuana,b
, and Mark Warnera
aCavendish Laboratory, JJ Thomson Avenue Road, Cambridge, CB3 0HE, United Kingdom
bDepartment of Mechanics and Engineering Science, Fudan University, Shanghai 200433, China
Yu et al 0 show curling of photochromic polydomain liquid crystal networks (LCNs) illuminated by
polarized ultraviolet (PUV). LCN sheets overshoot in that they curl until their edges reach an angle
much bigger than 90 degrees and they self-eclipse.
Photoisomerization gives macroscopic contraction from the destruction of orientational order by
bending the photosensitive guest molecules. We consider the dynamics of the rod-like trans
population converting to a bent cis population together with non-Beer light absorption 0. We take the
local incident light intensity to be the component of the Poynting flux normal to the locally-
illuminated surface, i.e. cosϴ of light intensity from the source, where ϴ is the local tilt angle of the
sample. The gradient of contraction in the sample makes it bend towards the light. The tilt angle ϴ
is a function of both the cis fraction and incident light intensity, integrated along the sheet as
accumulated curvature gives the tilt. A local cis fraction is triggered by the local light intensity,
which depends on the local tilt ϴ. So the photoisomerization and the photobending are coupled both
nonlinearly and non-locally.
The tilt in the photo-stationary state never reaches 90 degrees – there is no photo-stationary
overshoot. But it is significant that maximal curvature need not be where the light intensity falls
maximally, i.e. not in horizontal portions of the sheet. There is an incident light intensity for
maximum bending, since the bending curvature is a non-monotonic function of light intensity, both
statically and dynamically.
Our bending dynamics does overshoot: If light intensity is greater than that for maximum bending,
the curvature is a non-monotonic function both of the sample arc lengths and time. One could
expect a maximum curvature in the middle of the total sample arc length, at which cosϴ weakens
the light intensity towards the threshold value. This explains why overshoots only occurs beyond
certain light intensities and specimen lengths. After overshoot appears, the maximum curvature can
grow, despite eclipsing, and then attenuates in time since the cis population begins to decay in dark
regions and in those highly oblique to the incident beam. Through possibly several wobbles,
overshoot vanishes and samples approach the equilibrium shape. This complex phenomenon shows
bleaching waves play a crucial role in dynamical photobending and hence in future photo-
mechanical actuation.
References
1. Yu Y, Nakano M, Ikeda T. Nature, 2003, 425(6954): 145-145.
2. Corbett D, Warner M. Physical review letters, 2007, 99(17): 174302.
T 18
Graphene based electrodes for electrically switchable liquid crystal
contact lenses
S. Kaura,b
, D. Mistrya, H. Milton
a, I. M. Syed
a,c, J. Bailey
a, Y. J. Kim
a, K. S. Novoselov
a, C. J.
Jonesa,b
, P. B. Morgand and H. F. Gleeson
a,b
aSchool of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, United Kingdom bPresent address: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom
cSchool of Physics and Astronomy, University of Dhaka, Dhaka, 1000, Bangladesh dEurolens Research, University of Manchester, Manchester, M13 9PL, UK
For decades, liquid crystals have enhanced our lives with numerous display and non-display
applications which continue to grow to encompass innovations in other disciplines. The work
presented in this paper represents one such amalgamation of liquid crystal science with another
wonder material, graphene. At the University of Manchester, we have recently developed
electrically switchable liquid crystal contact lenses to correct Presbyopia, the age related
deterioration of the eye that affects everyone over the age of 50.1,2
Recently, we have further
developed this technology to successfully replace the standard electrode material, Indium tin oxide
(ITO) with electrodes made of graphene in the contact lenses.3
Transparent electrodes such as ITO are a necessary part of the electrically switchable liquid
crystal contact lenses as they are for numerous photonic devices. The high global demand for ITO
electrodes results in high manufacturing costs. In addition, ITO films are brittle and therefore
unsuitable for flexible electronics such as paper-like displays, and ITO deposition is problematic for
use in curved geometries such as the wearable contact lenses, which is our field of interest.
Therefore, alternative electrode materials can simplify and speed up contact lens construction
processes, and can be expanded to many other visual and numerical display applications.
Previous work has successfully demonstrated that graphene is an excellent choice for
electrodes in liquid crystal devices, with uniform switching and high optical transparency.4 In this
work, we demonstrate that graphene can successfully be deposited onto PMMA substrates to form
electrically switchable liquid crystalline contact lenses. The designed lenses are planar aligned and
capable of providing a continuous increase in optical power of up to +0.7± 0.25 D when electrically
switched. The lenses exhibit excellent optical contrast, demonstrated using polarisation microscopy
and the measurement of point spread functions. The work demonstrates that the transparency,
flexibility, electrical conductivity and adhesion to the substrates makes graphene an excellent choice
for use in applications such as smart contact lenses.
References 1 H. E. Milton, H. F. Gleeson, P. B. Morgan, J. W. Goodby, S. Cowling, J. H. Clamp, Proceedings of SPIE (2014), 9004, 90040H.
2 H. E. Milton, P. B. Morgan, J. H. Clamp, H. F. Gleeson, Optics Express (2014), 22(7), 8035.
3 S. Kaur, et al., To be sent to Nano Letters (2015). 4 P. Blake, et al., Nano Letters, (2008), 8 (6), 1704.
T 19
The investigation of mixtures of functionalized azocines – can LC phase
behaviour be promoted by irradiation?
J. Hussey, G. H. Mehl
1Department of Chemistry, University of Hull, HU6 7RX, UK
The photochromic behavior of azobenzenes is typically characterized by light induced cis-trans
isomerisations of the azo groups when irradiated with UV light. For such materials the trans form
tends to be the more stable isomer. Hence when azobenzene groups are incorporated into rod–
shaped molecules which can be mixed with liquid crystals or show liquid crystalline phase
behavior, irradiation results in a reduction of the stability or complete loss of the LC phase, as the
less linear cis isomer is formed. The investigation of materials which show photochromic
properties, when irradiated is however increasingly interesting [1] hence it is attractive to
investigate systems where LC is promoted on exposure to light. For azobenzene based systems,
which form the largest pcalss of reported photochromic groups this has so far not been possible.
The azocine moiety, shown in Figure 1, through known for more than hundred years, has only
recently been found to show photochromism [2,3]. This class of materials is highly bent, due to the
hydrocarbon linkage and thus the cis-conformer forms the more stable ground state isomer. It has
been reported that on irradiation a more rod shaped trans isomer is formed. [3-5] The chemistry of
the azocine group has not yet been investigated much, thus it was the aim to explore this.
In this contribution we report on the results of the efforts of an improved synthesis of diazocine
core, our results of functionalizing this core with mesogenic groups “R”, the chemical and
photochromic characterisation of these systems and we will compare these results with those
reported earlier [3-5]. We will report on the results of the investigation of the LC properties of these
systems as neat substances and in mixtures with suitable liquid crystals hosts and the effects on
nematic phase stability on irradiation with light and will structure properties correlations will be
disucssed.
.
[1] T. Kosa, L. Sukhomlinova. L.L. Su, B. Taheri, T.J. White, T.J. Bunning, Nature, 2012, 485,
347-349.
[2] H. Duval, Bull Soc.Chim. Fr. 1910, 7, 727-732
[3] R. Siewertsen, H. Neumann, B. Buchheim-Stehn, R. Herges, C. Nather, F. Renth, F. Temps, J.
Am. Chem. Soc. 2009, 131, 15594-15595.
[4] H Sell, C. Naether, R. Herges, Beilstein J. Org. Chem. 2013, 9, 1–7.
[5] S. Samanta, C. Qin, A. J. Lough, G. A. Woolley, Angew. Chem Int Ed. 2012, 51, 6452 –6455.
Figure 1: Azocine moiety
T 20
Improving the optical performance of liquid crystal contact lenses by
implementing axial alignment
J. Baileya,b, S. Kaura,b, D. Mistrya, H. F. Gleesona,b and J.C. Jonesa,b.
aSchool of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, United Kingdom bPresent address: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom
Presbyopia is an age related disorder which affects everyone over the age of 50 due to
natural deterioration of the eye. Contact lenses which have a switchable focus are currently being
investigated to assist people who do not want to wear glasses, but need correction for both far and
near vision. Liquid crystal contact lenses offer a solution to this problem as their refractive indices
are controllable by applying an electric field across the device 1-3
. Using a liquid crystal with a
larger bi-refringence results in a lens with a bigger focal power range. However, it has been
preivously shown by Milton et. al. that applying a field just above the Fréedericksz transition results
in significant scattering when using a higher bi-refringence liquid crystal 1,2
. This paper discusses
techniques which can be used to reduce the scattering when using a high bi-refringence liquid
crystal.
Scattering in the lens occurs from the circular asperities on the PMMA contact lens
substrates interrupting the alignment of the liquid crystal. These asperities occur from the laithing
manufacturing process used to construct contact lenses. Polishing the lenses to remove these
asperities is possible, but it is both time consuming and expensive. Instead, defects over the lens
were reduced by implimenting axial alignment, which followed the direction of the circular asperity
pattern. This was achieved by rubbing directly into the pedot electrode layers. Axial alignment
reduced scattering when switching the lens just above the Fréedericksz transition, which lead to an
improved optical performance. Reduced scattering enables the use of liquid crystals with a higher
bi-refringence. Our experiments, which used E7 as the intermediate liquide crystal layer, resulted in
a larger switching power (3.5 ± 0.5 D) than seen in similar liquid crystal contact lenses 1-3
.
References 1 H. E. Milton, H. F. Gleeson, P. B. Morgan, J. W. Goodby, S. Cowling, J. H. Clamp, Proceedings of SPIE (2014), 9004, 90040H.
2 H. E. Milton, P. B. Morgan, H. F. Gleeson, J. H. Clamp, Optics Express (2014), 22(7), 8035.
3 S. Kaur, H. Milton, D. Mistry, I. M. Syed, J. Bailey, K. S. Novoselov, A. K. Geim, J. C. Jones and H. F. Gleeson, Nano Letters (2015).
T 21
Acousto-optics in dispersed LC systems for applications in ultrasonics
Oksana Trushkevych, Tobias J. R. Eriksson, Silvaram N. Ramadas and Rachel S. Edwards
Department of Physics, University of Warwick ,Coventry, CV4 4AL, UK
Acousto-optic effects have been previously investigated in aligned LCs as they hold promise for
visualisation of acoustic fields [1-4]. Acousto-optic sensors based on homeotropic cells 200 μm
thick were developed commercially for use at oblique incidence in water tanks [5,6]. These
visualise acoustic field, but have the limitations expected from thick nematic films and suboptimal
geometry. Recently, acoustic clearing of a PDLC film by surface acoustic waves at high frequency
has been reported [7].
This paper presents developments toward using PDLC films as ultrasound sensors. We demonstrate
acousto-optic effects in PDLC films using longitudinal ultrasound at frequencies commonly used in
applications in non-destructive testing and medicine. Longitudinal waves at frequencies of 1 MHz
and 2 MHz are used to achieve acoustic clearing of PDLC films placed directly on the ultrasound-
generating transducers. Heating effects are carefully monitored using thermal imaging, and are
found not to be the main cause of PDLC clearing.
Figure1. a) PDLC film on top of a plate which is vibrating at 730 kHz (12:0 centrosymmetric mode)
showing clearing in the central area ~2mm in diameter; b), c) plate displacement amplitude
measured using laser vibrometry. The area of the strongest displacement is 1.9mm in diameter and
correlates well with the PDLC result.
The PDLC films are also shown to be able to image vibration of plates. The regions of the plates
with the largest displacement are visualised using PDLC with good resolution, with the
displacements confirmed using laser vibrometry. The vibrational properties of the plate are not
influenced significantly by the addition of the sensing film. The possibility of such imaging shows
promise for a variety of applications including fast characterisation of gas-coupled transducers for
applications such as gas-flow measurement. Overall, these first steps and demonstrated effects
suggest that acousto-optic effects in disperse LC systems and developing PDLC films for
ultrasound sensing is highly promising for applications in ultrasonic sensing, particularly in non-
destructive testing.
Acknowledgements: the authors would like to thank the University of Warwick Energy GRP for
the Research Award that funded this research, Merck for providing materials, and Dr. A.
Dyadyusha, Cambridge University, for valuable advice on PDLC.
References 1 O.A. Kapustina, Acoustical Physics, (2008), 54, 2, 180–196 2.
J. V. Selinger et al, Phys. Rev. E (2002) 66, 051708 3.
A. P. Malanoski et al, Phys. Rev. E (2004) 69, 021705 4.
V. A. Greanya et al, Liquid Crystals (2005) 32, 7, p933-941 5
J.S. Sandhu et al, Advances in Acoustics and Vibration, (2012), 275858; 6
G.L. Rodriguez et al, Ultrasonics,(2011) 51, 847 7 Y.J. Liu et al, Adv. Mat, (2011) 23, 1656
a) b) c)
P 1
Turbulent Textures - Art with Liquid Crystals
Ingo Dierking
School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
Textures of liquid crystals, observed in the polarized light of a microscope, can already by
themselves be considered as nature's little pieces of art. Due to their birefringence and varying
optical path differences, brightly varying textures can be observed easily. Defects at visible length
scales, due to the very small elastic constants, and repetitive patterns formed from the self-
organized superstructures contribute to the aesthetic appeal of optical liquid crystal textures.
Figure 1: Image produced from (a) a smectic fan-shaped texture, (b) a nematic texture with point
defects, (c) a Twist Grain Boundary phase, and (d) a nematic Schlieren texture.
The modern opportunities of digital image manipulation allow for an easy and creative way to
change the appearance of texture pictures, giving them possibly even more aesthetic appeal than the
already beautiful original research images. Certainly, they are reminiscent of many modern art
paintings found in galleries all over the world.
P 2
Using DPD Simulation to Study Phase Behaviour of Liquid Crystal-
Gold Nanoparticle Composite Materials.
Sarah Gray* and Mark R. Wilson
Department of Chemistry, Durham University, Durham, DH1 3LE, UK
It has been suggested, from experimental results1,2
, that
self-assembling 3-dimensional ordered arrays of gold
nanoparticles are produced with the aid of liquid crystal
ligands. These materials could see application to a huge
range of areas (photonics, electronics, optics) if the
nanoparticle structure was readily manipulated.
The typical molecular structure in these experiments is of
nematic-phase forming calamitic mesogens, laterally attached via a short alkyl thiol chain to
relatively small (<10 nm) spherical gold nanoparticles – the illustration above gives specific details
for the materials studied in reference [2].
This study uses Dissipative Particle Dynamics (DPD)
simulations to evaluate potential mechanisms involved in the
self-assembly process, and to gain understanding of the
factors that govern the phases produced. To the right is an
illustration of suggested structures
produced by a range of variations on the
molecular structure (description given
above)1. By simulating these
“supermolecules” at a molecular level, we
can either validate these proposed structures,
or put forward an alternative “picture” of
how alignment occurs.
We study a variety of different molecular architectures, as well as the impact of
anisotropic solvent and shearing, in an attempt to comprehensively describe the
phase behaviour of these materials. For instance, little mention is given to the
potential content of free liquid crystal molecules in these materials experimentally,
but we find that the amount of anisotropic solvent present has a significant impact
on the order parameter S2 of the bonded mesogens (illustrated left), and as such has
the potential to influence the proposed self-organisation process.
1X. Mang, X. Zeng, B. Tang, F. Liu, G. Ungar, R. Zhang, L. Cseh and G.H. Mehl,
J. Mater. Chem. (2012) 22:11101-11106. 2L. Cseh and G.H. Mehl, J. Am. Chem. Soc. (2006) 128:13376-13377
* presenting author, email: [email protected]
P 3
All Optical Switching of Nematic Liquid Crystal Films Driven by Localized
Surface Plasmons
Linda S Hirst
Department of Physics, University of California, Merced, USA
We demonstrate an all-optical technique for reversible in-plane and out-of-plane switching of
nematic liquid crystal molecules. Our method leverages highly localized electric fields (“hot spots”)
and plasmonic heating generated in the near-field region of densely packed gold nanoparticle layers.
These nanoparticles can be optically excited on-resonance at low power and optical
wavelengths. Using polarized microscopy and transmission measurements, we observe temperature
dependent switching from homeotropic to planar with an on-resonance excitation intensity of less
than 0.03 W/cm2 and no external applied electric field. In addition, we controllably vary the in-
plane directionality of the liquid crystal molecules in the planar state by altering the linear
polarization of the incident excitation. Using discrete dipole simulations and control measurements,
we demonstrate the spectral selectivity of our device in this new photonic application.
1M.T. Quint, S. Delgado, Z.S. Nuno, L.S. Hirst and S. Ghosh, Optics Express 23, 5, 6888 (2015).
P 4
High-Speed Microscope Imaging of Liquid Crystal Dynamics
C. Burkea, D. Emerson b, Y. Jinc, J. Guastoc, J. H. Adler b, T. J. Athertona
aDepartment of Physics and Astronomy, Tufts University, Medford, MA 02155 b Department of Mathematics, Tufts University, Medford, MA 02155
cDepartment of Mechanical Engineering, Tufts University, Medford, MA 02155
Microscopy has long been a key tool in the study of LCs: Polarizing Optical Microscopy (POM) is
a powerful technique for identifying LC phases based on textures that can also be used for
quantitative imaging. A key breakthrough in the field has been the use of 3D imaging techniques,
such as Fluorescence Confocal Microscopy (FCPM)5 and Confocal Anti-Stokes Raman (CARS)
6
microscopy. These powerful techniques enrich our understanding of domain wall structure and
defect topology, however, they are limited to static LC studies and lack the temporal resolution to
capture dynamic rearrangement. Indeed, few techniques are available to study dynamic phenomena
in LCs. The Convergent Beam method7 captures LC director information with sub-millisecond
resolution by observing the time variation of guided modes through a sample but lacks spatial
resolution. Attaching a video camera as the imaging device to POM is one possibility, and has
allowed studies of many phenomena including LC-mediated self-assembly of colloids and defect
dynamics. Unfortunately, the imaging is limited to about 60 fps. 3D video imaging at similar
framerates is possible with confocal microscopy using Nipkow disks or fast-scanning galvanic
mirrors8. Nonetheless, there is no existing technique that offers both the spatial and temporal
resolution necessary to study LC dynamics. Recently, we have begun to create such a technique by
combining high speed imaging with Polarizing Microscopy. To gain additional insights, the
experiments have proceeded in close collaboration with multigrid nematodynamics simulations and
optical modeling. This study presents some initial results for a Freedericksz cell as a validation
exercise, as well as an In-Plane switching device.
5 O. D. Lavrentovich, “Fluorescence confocal polarizing microscopy: Three-dimensional imaging of the director”,
Pramana, 61 373-384 (2003) 6 E. A. Büyüktanir, K. Zhang, A. Gericke and J. L. West,
“Raman Imaging of Nematic and Smectic Liquid Crystals”,
Molecular Crystals and Liquid Crystals, 481 39-51 (2008) 7 L. Z. Ruan and J. R. Sambles, “Dynamics of a twisted nematic cell using a convergent beam system”, Journal of
Applied Physics, 92, 4857 (2002) 8 O. D. Lavrentovich, “Confocal Fluorescence Microscopy”, chapter in “Optical Imaging and Spectroscopy”, John
Wiley & Sons (2003)
P 5
Synthesis and Properties of Novel Liquid Crystals with Bulky Terminal Groups
Designed for Bookshelf Geometry Ferroelectric Mixtures
Rami Pasha and Michael Hird
Department of Chemistry, University of Hull, Hull, HU6 7RX
This research programme will be concerned generally with the ferroelectric liquid crystals for
microdisplay applications. Ferroelectric liquid crystal displays switch 1000 times faster than
conventional liquid crystal displays, and offer much higher resolution, and hence are suitable for
microdisplay applications. Novel liquid crystals will be synthesized, with the broad aims of
enhancing switching speeds and improving the alignment of the molecules in the display. All the
final products will be evaluated for their mesomorphic properties and a wide range of other physical
properties, and the most suitable compounds will be formulated into mixtures for evaluation in
prototype microdisplays.
Difluoroterphenyls1 are well-recognised as excellent host materials for low viscosity, fast-switching
ferroelectric mixtures. Ferroelectric liquid crystal displays switch faster than conventional liquid
crystal displays, and offer much higher resolution, and hence are suitable for microdisplay
applications2.
The synthesis and mesomorphic properties of a systematic range of ortho difluoroterphenyls and
ortho difluoroquartetphenyls with bulky terminal chains are detailed. The bulky terminal chain
consists of a methoxy-4,4-dimethylpentyl group, a trimethylsilyl unit and a dimethylethyl group.
All the final products will be evaluated for their mesomorphic properties and a wide range of other
physical properties, and the most suitable compounds will be formulated into mixtures for
evaluation in prototype microdisplays. The compounds give a nematic phase however, all the
compounds give a SmC phase.
1- G. W. Gray, M. Hird, D. Lacey and K. J. Toyne, J. Chem. Soc., Perkin Trans. 2, 1989, 2041.
2- M. Walba, D.J. Dyer, X.H Chen, U. Muller, P Cobber, R. Shao, and N.A Clark, Molecular Crystal and Liquid
Crystal 1996, 288,83.
P 6
Homeotropic alignment in switchable optical power, liquid crystal contact
lenses.
D. Mistrya, I. M. Syed
a,c, S. Kaur
a,b , H. Milton
a, J.Bailey
a,b, J.C. Jones
a,b, P. B. Morgan
d,
J. H. Clampe and H. F. Gleeson
a,b
aSchool of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, United Kingdom bPresent address: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom
cUniversity of Dhaka, Dhaka, 1000, Bangladesh dEurolens Research, University of Manchester, Manchester, M13 9PL, UK
eUltravision CLPL, Leighton Buzzard, LU7 4RW, UK
A liquid crystal contact lens based on homeotropic device geometry with a switchable optical
power has been constructed1. This builds on previous work on homogenously aligned lenses
2. Such
devices have promising ophthalmic applications for effective treatment of presbyopia, an age-
related disease of the eye affecting nearly 100% of the population by middle age. Presbyopia is a
stiffening of the accommodating (“auto-focus”) lens of the eye meaning it cannot focus on objects
as close to it as a young eye can.
The contact lens contains the negative dielectric liquid crystal MLC-20813. Switching this
material gives the lens a continuously variable optical power of up to 2.00 ± 0.25 𝐷. The maximum
change in power is achieved with an applied voltage of 7.1 𝑉𝑟𝑚𝑠. This variable additional change in
optical power makes the device an ideal treatment for presbyopia as the user can turn on the extra
optical power when they are performing near visual tasks, as and when required.
Using a homeotropic instead of homogeneous geometry in a contact lens has several advantages:
The lens’ unpowered state is polarisation-independent so produces a higher quality image compared
to a birefringent state. This means a low-powered device can be designed with optimal distance
vision which is more crucial and used more frequently than near vision;
The lens construction becomes easier as only one surface needs to be rubbed. This was chosen to be
the concave surface which is much easier to rub uniformly;
The two lens substrates do not need to be aligned with respect to one another thus simplifying
construction.
Acknowledgements
I.S. thanks the UK Department for International Development (DFID). D.M. thanks the EPSRC
and UltraVision CLPL. The authors would like to thank Prof. John Goodby and Dr. Stephen
Cowling.
References 1 I. Syed, S. Kaur, H. E. Milton, D. Mistry, J. Bailey, J. C. Jones, P. B. Morgan, J. H. Clamp, H. F. Gleeson Submitted to Applied Optics 2015
2 H. E. Milton, P. B. Morgan, J. H. Clamp, H. F. Gleeson Optics Express (2014), 22(7), 8035.
3 Merck Chemicals Ltd. Physical properties of MLC-2081are quoted in the Merck Data Sheet.
P 7
The dynamic response of nematic devices with an unconventional geometry.
Marianna Minarova,
a Shajeth Srigengen,
a Cliff Jones
a,b and Helen F. Gleeson
a,b
aSchool of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
bSchool of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
Nematic liquid crystals are increasingly used for non-display applications such as sensors or
electro-optic devices and interconnects. One such area that is attracting increasing attention is the
use of liquid crystals in switchable contact lenses for the correction of presbyopia (the need for
reading glasses in the over-50s)9, 10
. The contact lens geometry requires a layer of liquid crystal
enclosed by substrates of differing curvatures, such that the device thickness varies as a function of
radial distance in the lens (see figure). In the lens, the change in refractive index of the nematic
liquid crystal layer that occurs on application of a voltage above the threshold voltage causes a
change in the focal length of the lens.
The switching of the liquid crystal contact lens is more complicated than in conventional devices
with parallel substrates. The threshold voltage (Vth) and response time (τon) of a planar nematic
layer are:
Vth = π√k11
ε0Δε, τon =
ηd2
ε0ΔεV2 − k11π2,
where k11 is the splay elastic constant and Δε is the dielectric anisotropy of the material. The
response time of the liquid crystal layer is clearly strongly dependent on the thickness. We report a
detailed study of the electro-optic response of a nematic liquid crystal layer of non-uniform
thickness. The response of a parallel-aligned wedge cell designed to model the liquid crystal layer
in the contact lens is described and compared with parallel devices of different thicknesses. The
study gives an insight into the dynamics of liquid crystal based lenses and offers an understanding
of some of the electro-optic effects reported to date1,2
.
9 H. E. Milton, H. F. Gleeson, P. B. Morgan, J. W. Goodby, S. Cowling and J. H. Clamp, ‘Switchable liquid crystal
contact lenses; dynamic vision for the ageing eye,’ Proc. of SPIE Vol. 9004 90040H-1-6 (2014) 10
H.E. Milton, P.B. Morgan, H. F. Gleeson and J. H. Clamp, ‘Design and operation of PMMA-based liquid crystal
lenses for contact lens use,’ Optics Express, 22(7) 8035040 (2014)
Optical zone
LC layer
Mating surface
Lower substrate Upper substrate
50 μm
Lower substrate
67 μm
P 8
Measuring the temperature dependence of the anisotropic viscosity of nematic liquid crystals using laser tweezer techniques
David L. Weia, Mark R. Dickinson
a, James Bailey
b, Cliff Jones
a,b and Helen F. Gleeson
a,b,
a School of Physics and Astronomy, University of Manchester,
Manchester M13 9PL, UK b School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
The dynamic response characteristics of a liquid crystal (LC) device are dependent upon its
viscosity coefficients and dielectric anisotropy. Optimisation of these properties allows for LC
devices with faster response times. With such a wide variety of LC materials, information regarding
the viscous properties is often incomplete. The effect of external stimuli, including temperature and
electric fields, on these properties provides valuable information for device behaviour. Laser
tweezers provide alternate routes to determine this information, as the dimensions are well suited to
these techniques.
Manipulation of micron-sized particles with optical tweezers provides a unique method for LC
systems to be studied. Dispersed colloidal particles can be trapped and used to probe the
fundamental properties of these systems, particularly anisotropic viscosity coefficients in the low
Ericksen regime. These properties can be explored under a variety of external conditions, and with
different tweezing techniques such as viscous drag measurements or particle tracking.
Optical tweezers also allow the forces acting on colloidal particles in these systems to be explored.
The response of trapped particles can provide insight into the behaviour and motion of particles in
such systems. The influence of anisotropic LC properties, and of external stimuli, on this behaviour
can be studied for a wide variety of materials.
Cells fabricated with PEDOT:PSS are also investigated as an alternative to ITO, which is shown to
impose limitations on such measurements.
Acknowledgements
The author would like to thank the EPSRC and Merck Chemicals Ltd.
P 9
Molecular Dynamics Simulation of Fibre Formation
Alireza Dastan and Doug Cleaver
Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK
In this poster, fibre self-assembly, which is a very common phenomenon in a range of areas, was
investigated through molecular dynamics simulation of a mixture of spherical (solvent) and discotic
particles. Using the Coarse-Grained method, the interaction between discotic particles is governed
by the well-known Gay-Berne potential, while the spherical particles interact with each other
through Lennard-Jones potential. Three different shape parameters for discotic particles (length to
breath ratio) and also three anisotropy values in their potential energy were considered in this study
and the effects of these parameters on the fibre self-assembly were studied. Results showed that the
self-assembly of fibres is a hierarchical process. It means that, at the first step of this process, many
threads of 4-6 face-to-face oriented discotic particles form and then some of them attach laterally
and make a cluster. This cluster grows both laterally and longitudinally and forms the final fibre. It
was observed that the process of fibre self-assembly is a function of temperature. That is, only in a
narrow-range of temperature, a defect-free fibre forms and below this range, the self-assembled
structure is a defected one. The outcome of this study can shed light on our understanding of the
fibre formation process and also shows some of important parameters affecting the final structure.
The results may possibly be used in the control of fibre self-assembly.
P 10
Polarized Raman Spectroscopy Measurements of Liquid Crystal Order
Parameters
Zhaopeng Zhang, Helen F Gleeson
School of Physics and Astronomy University of Manchester, Manchester, M13 9PL
Polarized Raman Spectroscopy (PRS) is one of the experimental methods which can be employed
to deduce orientational order parameters in liquid crystals. Previous studies have produced values of
the measurement of P200 that are in excellent agreement with theory1,2
and relatively recently it has
also been demonstrated that reliable measurements of P400 can be obtained3. However, a key
assumption of the methods used is that the vibrational direction for selected Raman-active mode is
coincident with the molecular long axis. We have relaxed this assumption, allowing a small tilt
angle 𝛽0 between the vibration direction and the molecular main axis. Our results indicate a strong
effect on the depolarisation ratio value when 𝛽 0 is non-zero, increasing as 𝛽 0 is increased.
Consequently, the order parameters deduced from fits to the experimentally determined
depolarization ratio are different depending on whether or not 𝛽0 is included.
It has also long been known that the order parameters deduced from PRS using different vibration
modes are found to be different within the same sample. As a result, only certain vibration modes
can be reliably selected for analysis, limiting the application of PRS. We have investigated this
issue and a reasonable explanation has been given by introducing a different dipole symmetry
model, specifically we assume that the phenyl stretching mode has cylindrical symmetry while the
cyano stretching mode has elliptic cylindrical symmetry. By accounting for this different symmetry
model, it is possible to get exactly the same set of order parameters from both phenyl and cyano
stretching modes. However, the introduction of additional fitting parameters does not necessarily
offer a robust fitting method to deduce order parameters using this concept.
References
1 S. Jen, N. A. Clark, P. S. Pershan, and E. B. Priestley, J. Chem. Phys. (1977),66, 4635
2 W. J. Jones, D. K. Thomas, D. W. Thomas, and G. Williams, J. Mol. Struct. (2004), 708, 145.
3 C. D. Southern and H. F. Gleeson, Eur. Phys. J. E (2007), 24, 119.
P 11
Novel Resists for Nanofabrication on Insulating Substrates
Karolis Virzbickasa, Farhan Hasan
a, Greg O’Callaghan
b, Dennis Zhao
b, Jon A. Preece
b and Alex P.
G. Robinsona
aSchool of Chemical Engineering, University of Birmingham, UK
bSchool of Chemistry , University of Birmingham, UK
Electron beam lithography is widely used in high value low volume manufacturing, and in research,
of nanoscale electronics and micromechanical systems and nanotechnology. However, it is not
possible to directly pattern poorly conductive or insulating substrates with feature sizes smaller than
about 100 nm due to charging by the electrons. A number of existing strategies such as the use of
charge dissipation layers or patterning of intermediate moulds have been investigated but typically
add complexity and cost without necessarily significantly improving the situation. In this project,
we investigate and develop photoresists using Triphenylene organic conductors to incorporate the
charge dissipation strategy directly into the lithographic imaging layer. We characterise the
conductivity, lithographic, etching and other properties of the new resists and investigate their
performance for nanoscale patterning of substrates such as glass and gallium nitride.
P 12
Structure and organisation in chromonic phases: MD simulation study of Azo
dyes in aqueous solution
Chami Fa and Wilson M
a
aDepartment of Chemistry, Durham University, Durham, DH1 3LE, UK
Chromonic liquid crystals occur widely in aqueous dispersions of many formulated products such
as pharmaceuticals and the dyes used in inkjet printing. They are also used in material science for
fabricating highly ordered thin films and anisotropic carbons. Chromonic mesophases are usually
formed in water from disk-like or plate-like molecules1. At low concentrations aggregates are
formed in solution; but when the volume fraction is sufficiently high, liquid crystals occur.
The azo dye Acid red 266 known as Nylomine, is a disparate ionic dye that forms chromonic
mesophases at unusually low concentrations (0.25\% (w/w)). It has a chemical structure that is
similar to that of ESY (Fig.1b) , but its behaviour is very different. Nylomine exhibits a nematic
tiger-skin texture at 1\% (w/w) and does not show a sharp N/M transition. Despite the low
concentration, Nylomine aggregates have a cross area far larger than the molecular area2-4
.
In an attempt to gain insight on aggregation and structure of this chromonic mesophase, we carried
out molecular dynamics simulation in water at 6 % (w/w) on a large system with four different
starting configurations. The binding energy of Nylomine dimer was estimated from steered MD
simulation and from the potential of mean force.
can the building unit in Nylomine be much larger species than dimer or is the probability of
branching in stacks.
(a) Acid red 266 dye (Nylomine) (b) Sunset Yellow dye (Edicol )
Fig.1 Chemical structure of azo dyes
References 1. John Lydon, Handbook of Liquid Crystals Volume 6. Nanostructured and Amphiphilic Liquid Crystals (2014).
2. Bernd Neumann, Klaus Huber and Peter Pollmann, Phys. Chem. Chem. Phys. (2000), 2, 3687.
3. Bernd Neumann, Langmuir (2001), 17, 2675.
4. J. W. Jones, Helen Wheatcroft, A. P. Ormerod, Abdullatif Alfutimie, Douglas J Edwards and G. J. T. Tiddy, in press
NaO3S
N
N
NH2Cl
CF3
OH
NaO3S
O
N
N SO3Na
H
P 13
AFM study of supermolecular dendritic liquid quasicrystals
R. B. Zhang,a X. B. Zeng,
a V. Percec
b and G. Ungar
a,c
a Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK b Department of chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
c Department of Physics, Zhejiang Sci-Tech University, Hangzhou, China
The self-assembling dendron can from cones which further assemble into supramolecular spheres.
These spheres can then generate spherical phases with 3D periodicity. The large majority of such
periodic 3D structures show Pm3̅n1 or P42/mnm
2. Symmetries. They are featured by alternating
densely and sparsely populated layers of spheres. One way of representing these structures is to
view them as tilings that cover an infinite plane using only squares and equilateral triangles3. Each
tile is a column containing individual micelles, having periodicity along c. Only three kinds of tiles,
one square and two triangular, are needed to construct these structures. A sparse layer of the Pm3̅n
represents a simple square 44 tiling, while that of the tetragonal P42/mnm phase has the ubiquitous
32434 Arhimedean tiling. The presence of the 3
2434 tiling was the first hint of a dodecagonal
quasiperiodic phase in supramolecular spherical dendrimers. In 2000 the first liquid quasicrystal
(LQC) formed by a dendron was discovered by our group using synchrotron X-ray diffraction two
decades after Shechtman’s seminal discovery of LQCs in metals. The recorded diffraction pattern
from a single domain showed a crystallographically forbidden 12-fold rotational symmetry4. Using
quasiperiodic tiling, the same elements (square and triangle) can be used to construct models of the
LQC. However, in the real LQC the micelles would also be somewhat away from the ideal positions
assumed by our starting model. Here we studied the LQC tiling using atomic force microscopy.
References 1. S. D. Hudson. et al., Science, (1997), 278, 449.
2. G. Ungar. et al., Science, (2003), 299,1208.
3. X. B. Zeng, G. Ungar, philosophical magazine, (2006), 86, 1093.
4. X. B. Zeng. et al, Nature, (2004), 428, 157.
Spheres on sparse net
at z=1/4, 3/4
Spheres at z=0, 1
z=1/2
Decorated sparse net
P 14
Hexagonal Close Pack Structures in Thermotropic Liquid Crystals
M. H. Yena, J. Chaiprapa
a, X. Zeng
a, L Cseh
b, G. H. Mehl
b, and G. Ungar
a
aDepartment of Materials Science and Engineering, University of Sheffield, Sheffield, S1 3JD, UK
bDepartment of Chemistry, University of Hull, Hull, HU6 7RX, UK
Wedge-shaped dendron-based mesogens can form columnar or spherical supramolecular assemblies.
The spherical “micellar” aggregates self-assemble into 3-D cubic phases. However, until now no
close-packed structures have been reported in thermotropic LCs, either face-centred cubic (FCC) or
hexagonal close packing (HCP). This is due to the inaccessibility of the octahedral interstices in the
close pack structures to the flexible chains of the micellar corona.
In our study, a close pack structure was observed in the minidendron-alkane blends. We found that
in a mixture of sodium 3,4,5-tridedocyloxybenzoate salts (12-12-12Na) with 15% n-C19H40, the
HCP phase is obtained. Similar situation was also observed in rubidium 3,4,5-
tridedocyloxybenzoate salts (12-12-12Rb). We suggest that the role of the added alkane is to fill the
octahedral interstices in the HCP. We then replace n-C19H40 by n-C19D40. The deuterated alkane can
be distinguished by neutron scattering from the alkyl tails of the minidendrons. The position of the
added alkane thus can be located.
The electron or scattering length density maps can be reconstructed from the diffraction patterns.
Figure 1 (a) shows the top view of the electron density (ED) map in the HCP phase. The low ED
region is located at the octahedral interstices. Interestingly, in the neutron scattering length density
(NSLD) maps shown in Figure 1 (b), it is the high NLSD that is located at the octahedral interstices.
Thus deuterated alkane fills the material-deficient octahedral vacancies and stabilizes the close pack
structure. This is the first time the close pack structure is reported in thermotrpic liquid crystals.
This work also demonstrates the power of combined X-ray and neutron diffraction in the study of
LC self-assembly.
Figure 1 The top view of (a) ED map and (b) NSLD map; (c) ED and NLSD map in a HCP unit cell
(green: high-ED; red: low-ED; blue: high-NSLD)
References
G. Ungar, X. Zeng, Soft Matter (2005), 1, 95
(a)
(b)
(c)
P 15
Chessboard and Wigwam phases in X-Shaped Polyphiles
Huanjun Lua, Feng Liu
a, b, Xiangbing Zeng
a, Goran Ungar
a, Hergold Ebert
c and Carsten Tschierske
c
aDepartment of Materials Science and Engineering, University of Sheffield, Sheffield, S1 3JD, UK bState Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
cInstitute of Organic Chemistry, Marten-Luther University, Halle, Germany
A variety of phase morphologies have been observed in X-shaped liquid-crystalline polyphilies1.
Most prominent are a series of 2D honeycombs and novel 3D-ordered mesophases2, 3
. The present
X-shaped polyphilic molecule HEP14 is made up of a rigid rod-like aromatic core with an alkyl and
a semiperfluorinated chain attached laterally to opposite sides of the aromatic moiety. This
compound forms five phases on cooling from 180 ˚C to 100 ˚C. The first two high-temperature
phases, p4mmHT and p4mmLT are both 2D columnar (plane group p4mm), while the lattice parameter
changes from a = L (L = molecule length) to a = L√2. Combined with the reconstructed electron
density map, this suggests that they are both square
honeycombs. In the p4mmHT phase all cells are the
same with mixed alkyl and semiperfluorinated chains.
In the p4mmHT, alkyl and semiperfluorinated chains are
partially separated in alternative chessboard cells. On
cooling, the squares contract into rhombs, resulting in
a rectangular honeycomb (p2mm phase). After that, a
2D-3D transition takes place with the reorientation of
the aromatic rods. In the primitive tetragonal 3D phase
(P4/mmm), the rods twist to form a cage-like “double
wigwam” structure (see Figure) with the alkyls (red)
inside and the fluorocarbon chains (blue) outside the
cage. At still lower temperatures the p2mm rhombic
honeycomb phase re-enters, this time with complete alkyl-fluoroalkyl microphase separation. This
remarkable phase sequence is a consequence of the competition between tendencies for mixing,
phase separation and space filling. To our knowledge the “wigwam” phase is the first example of a
3D LC honeycomb.
References 1. G. Ungar, C. Tschierske, V. Abetz, R. Holyst, M. A. Bates, F. Liu, M. Prehm, R. Kieffer, X. B. Zeng, M. Walker, B. Glettner, A.
Zywocinski, Adv. Funct. Mater. (2011), 21, 1296.
2. B. Glettner, F. Liu, X. B. Zeng, M. Prehm, U. Baumeister, M. Walker, M. A. Bates, P. Boesecke, G. Ungar, C. Tschierske, Angew. Chem.
Int. Ed. (2008), 47, 9063.
3. B. Chen, U. Baumeister, S. Diele, M.K. Das, X.B. Zeng, G. Ungar, C. Tschierske, J. Am. Chem. Soc. (2004), 126, 8608.
P 16
Novel mesomorphic behaviour of a chirally-doped liquid crystal dimer,
exhibiting the twist-bend nematic phase.
Craig T. Archbold
a*, Richard J. Mandle
a, Edward J. Davis
a, Stephen J. Cowling, John W. Goodby
a
a
Department of Chemistry, The University of York, York, YO10 5DD
In recent years, the twist-bend nematic (NTB) liquid crystal phase has been an area of particular
interest because of its potential for use in devices. The focus thus far has been on the determination
of its structure and properties.1-4
However, there has been little study into the effects of chiral
dopants on the properties of materials displaying the NTB phase despite the prevalence of chiral
liquid crystal phases in devices. This work was undertaken in the hope of furthering our
understanding of the properties of materials that exhibit the NTB phase as well as their possible
technological applications.
We demonstrate the effects of doping a liquid crystalline material exhibiting an enantiotropic NTB
phase (Compound 1) with two different chiral dopants (Compounds 2 and 3), the structures of
which are given in Figure 1.
Figure 2: Structures of Compounds 1-3.
Across a range of dopant weight percentages, several interesting properties were observed. These
included a direct isotropic to NTB transition (Figure 2 (a)), showing for the first time the natural
texture of the NTB phase rather than the paramorphotic texture observed on transition from the
nematic phase; a previously unobserved, weakly birefringent phase, appearing only upon annealing
slightly above the isotropic to NTB transition temperature (Figure 2 (b)); and the emergence of a
particularly wide temperature (≈ 10 °C) Blue Phase III (BPIII) (Figure 2 (c)). These results
demonstrate a clear effect on the properties of these materials upon introduction of a chiral dopant,
however the NTB phase itself is largely unaffected when viewed on an untreated glass slide.
Figure 3: a) Direct isotropic to NTB transition at 80.3 °C b) Weakly birefringent phase observed
upon annealing at 80.6 °C for 2 hours c) BPIII observed at 82.3 °C.
1. L. Beguin et al., Journal of Physical Chemistry B, 2012, 116, 7940-7951.
2. M. Cestari et al., Physical Review E, 2011, 84.
3. R. J. Mandle et a.l, Journal of Materials Chemistry C, 2014, 2, 556-566. 4. D. Chen et al., Proceedings of the National Academy of Sciences of the United States of America, 2013, 110, 15931-15936.
a) b) c)
Compound 1:
90%
Compound 3:
10%
Compound 1:
90%
Compound 3:
10%
Compound 1:
95%
Compound 2: 5%
P 17
Investigation of the Electric Field-Induced Behaviour of Biaxial, Smectic Liquid
Crystals using a Phase Sensitive Detection Method
J. W. Fostera, J. Ish-Horowicz
a, V. P. Panov
a, M. Nagaraj
a and J.C. Jones*
a,b
a School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
b School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
The common nematic liquid crystal phase used in television and mobile-phone displays is uniaxial
and has simple cylindrical symmetry. Applying an electric field reorients the long axis of the system
causing the desired change in optical properties to make the optical contrast of the display. However,
this is inherently a slow process. One approach to forming a much faster response is to use a biaxial
phase, where the system is biaxial and has orthorhombic or mono-clinic symmetry. With such
symmetries the material properties also differ along directions perpendicular to the conventional
symmetry axis. Field-induced transitions have the potential to be far faster than in conventional
uniaxial liquid crystals. The best characterised example is the ferroelectric Sm-C*, where the speed
of the transition arises from the ferroelectric polarisation but the electro-optics are greatly affected
by biaxiality [1].
We present the investigation of electric field-induced behaviour of a difluoro-terphenyl based liquid
crystal- MH222 (2',3'-difluoro-4-heptyl-4"-nonyl-1,1':4',1"-terphenyl) in its Sm-A and Sm-C
mesophases using a phase sensitive detection method. A home-built experimental set-up designed to
measure dielectric permittivities at high electric fields [2] will be shown. The set-up is based on the
principle of applying a sine wave test voltage to the liquid crystal device via a high voltage
amplifier and deducing the impedance of the device from the complex voltages measured by a lock-
in amplifier. Extensive calibration procedures were carried out using devices of various electrode
geometries and a standard liquid crystal of well-known permittivity.
The general utility of the setup is demonstrated though the measurement of the temperature and
electric field dependence of two permittivity components in the uniaxial nematic and Sm-A
mesophases; and the calculation of the three permittivity components in the biaxial Sm-C
mesophase of MH222 [3]. Also presented are the results of investigations into the elastic constant of
the material and the anchoring energy of the experimental cells used.
References 1. J. C. Jones et al, Ferroelectrics. (1991), 121, 91-102.
2. D. Dunmur et al, J. Phys. E: Sci. Instrum. (1987), 20, 866.
3. J. C. Jones and E. P Raynes, Liq Cryst (1992), 11, 199-217.
P 18
UV stability of liquid crystal lasers during polymer stabilisation
Shuyu Yang, Michael P. Shaver, Philip J.W. Hands a
School of Chemistry, University of Edinburgh, King’s Buildings, Edinburgh, EH9 3FJ, UK
a School of Engineering, University of Edinburgh, King’s Buildings, Edinburgh, EH9 3JF, UK
Dye-doped chiral nematic liquid crystal (LC) photonic band-edge lasers offer new disposable solutions for
bespoke coherent light sources. Recent advancements include the gradient pitch LC laser [1], whereby a
spatial variation in chiral pitch length (and dye concentration) across the cell, enables continuous wavelength
tuning of the laser through simple variation of the spatial location of the focussed pump beam. Pitch
gradients are formed through the diffusion of 2 lasing mixtures, each optimised for a different emission
wavelength. Unfortunately, perpetual diffusion limits the stability of the pitch gradient for only a few
weeks/months, ultimately decaying to a uniform pitch with no wavelength tuning capability. Polymer
stabilisation has been hypothesised as an appropriate technique to fix pitch gradients and prevent further
diffusion. Unfortunately, previous experiments have found that lasing is often no longer possible after
polymer stabilisation, or occurs with significantly reduced performance [2]. This has been attributed to poor
UV stability of the organic laser dyes, but has not been studied extensively.
Fig 1. Gradient-pitch LC laser (left). Images of different dye-doped LC laser cells with increasing UV exposure (right), with and
without polymer-stabilisation (2% RM257, 0.5% Irgacure 819). The ticks and crosses denote successful and unsuccessful lasing
achieved respectively. (Note NMR experiments determined minimum time for complete polymerisation is 1 minute at 46 mW/cm2).
This paper investigates the UV stability of a selection of organic dyes (DCM, PM597, PM597-8C9, PM650,
Ph660) in LC lasers stabilised by the polymer RM257. We establish that UV damage is attributed to free-
radical attack of the dye, caused by the presence of photoinitiator (Irgacure 819). Such damage reduces dye
absorption/fluorescence capabilities and increases lasing thresholds. The effect is particularly pronounced in
the popular dye DCM. However, alternative choices of dye (particularly pyrromethenes) were shown to be
more resistant to such attack, beyond the timescales required for complete polymerisation of the sample (>1
min). This enables polymer stabilised gradient pitch LC laser systems to be successfully fabricated, with
negligible effect upon laser performance. An additional note of discovery was that UV stability of LC lasers
(containing no polymer) was far better than previously expected (exceeding 1 hour at 46 mW/cm2). This
result bodes well for the future applications and commercialisation of LC laser sources.
References 1. S.M. Morris, P.J.W. Hands, et al., Optics Express, 16, 18827 (2008)
2. J. Schmidtke, W. Stille, et al., Advanced Materials, 14, 746 (2002)
P 19
The investigation of mixtures of dimers forming a N and a Nx/tb phase
E. Ramou1,2
, Z. Ahmed1, C. Welch
1, G. H. Mehl
1
1 Department of Chemistry, University of Hull, HU6 7RX, UK
2 Department of Physics, University of Patras, 26504 Patras, Greece
The investigation of an additional thermotropic LC phase, termed often either Nx or Ntb, found in
dimeric liquid crystals below the nematic phase, has attracted considerable interest over the last few
years. This Nx/tb phase is typically characterized by POM textures easily taken for that of a smectic
phase, but the absence of small angle reflections in X-ray data indicates a structure with features of
a nematic phase. Solid state NMR data and optical thin film investigations are indicative of the
presence of chiral structures. Some TEM data and electro-optical studies suggest the possibility of
twist-bent arrangements, hence the identification as Ntb, however some of this data is still discussed
controversially. Phase structures, such as a splay-bend or a chiral domain structure or others such as
a nematic hexatic phase are a possibility too, thus the provisional term Nx phase. In order to
investigate this question further, mixtures of a material reported to show an Nx phase with a
conventional nematic dimesogen were carried out.
Binary mixtures of cyanobiphenyl dimers that exhibit a Nu-Nx phase transition are reported and
investigated by Polarizing Optical Microscopy (POM), Differential Scanning Calorimetry (DSC)
and for selected compositions by XRD studies. The initial liquid crystal dimers are the a,ω-bis(4,4’–
cyanobiphenyl)nonane (CB9CB)1 that is already reported to exhibit a weakly first order Nu-Nx
transition and its corresponding ether linked dimer CBO9OCB2 that exhibits only the Nu phase.
For mixtures richer in CBO9OCB the Nx phase is monotropic, observed only on cooling. The phase
identification and characterization is performed by POM, as the Nu-Nx transition is too weak to be
captured by DSC scans. Furthermore it was found that the Nu-Isotropic and Isotropic-Nu transitions
are exhibiting strongly biphasic regions. On the other hand, as the mixtures become richer in the
CB9CB, the Nx phase starts to appear in the DSC scans as a weakly first order transition during
cooling and heating. Moreover, for some of the mixtures the DSC scans multiple peaks for the Nu-
Isotropic and Isotropic-Nu transitions, suggesting surprisingly complex transition behaviour.
The phase diagrams constructed depict a linear dependence on the composition for the Nu-Isotropic
and Isotropic-Nu transitions and a substantially linear behaviour for the melting point and the
crystallization. As for the Nx-Nu and Nu-Nx transitions, the phase diagrams reveal a stabilization of
the formation of the Nx phase at an almost fixed temperature for heating and cooling in the stability
range of this phase.
E.R. acknowledges support by the EU through the ERASMUS+ Placements programme.
References [1] C.S.P. Tripathi, P. Losada-Perez, C. Glorieux, A. Kohlmeier, M.G. Tamba, G.H. Mehl, Phys. Rev.E (2011), 84, 041707.
[2] C. T. Imrie and P. A. Henderson, Chem. Soc. Rev. (2007), 36, 2096.
P 20
Liquid Crystal Infiltrated Gyroid Optical Metamaterials
J.A. Dolana,b
, T.J. Athertonc, J.J. Baumberg
b, U. Steiner
d, and T.D. Wilkinson
a
aDepartment of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
bDepartment of Physics, University of Cambridge, Cambridge, CB3 0HE, UK cPhysics and Astronomy Department, Tufts University, Medford, MA 02155, USA
dAdolphe Merkle Institute, University of Fribourg, 1700 Fribourg, Switzerland
Block copolymers consisting of two or more covalently tethered and chemically distinct
homopolymers may self-assemble into a range of equilibrium morphologies by microphase
separation. One such morphology is the gyroid, the only triply periodic constant mean curvature
surface also to possess an intrinsic chirality (Figure 1). As the characteristic length scale of polymer
self-assembly is often deeply sub-wavelength for visible light, block copolymer gyroids represent a
fascinating route by which to fabricate truly three dimensional optical metamaterials1. Gold gyroids
templated in this manner exhibit a striking range of optical properties imparted by the particular
sub-wavelength structure. These properties include highly anisotropic linear and circular dichroism,
and a directionally dependent plasma frequency which is greatly depressed from that of the
constituent gold2. Furthermore, infiltration of the gyroid metamaterial with various dielectric media
allows the tuning of its optical response across the visible spectrum3. However, when infiltrated
with a nematic liquid crystal, not only is the optical response of the material modulated, but also an
intriguing liquid crystal defect structure is templated4. We therefore present progress towards the
characterisation of the optical properties of gold gyroid optical metamaterials infiltrated with
nematic liquid crystals.
Figure 4: a) The single gyroid morphology viewed along b) the [100] chiral direction, c) the [111]
chiral direction, and d) the [110] achiral direction1.
References 1. J.A. Dolan, B.D. Wilts, S. Vignolini, J.J. Baumberg, U. Steiner, and T.D. Wilkinson, Adv. Opt. Mater. (2015), 3, 12
2. S. Vignolini, N.A. Yufa, P.S. Cunha, S. Guldin, I. Rushkin, M. Stefik, K. Hur, U. Wiesner, J.J. Baumberg, and U. Steiner, Adv. Mater. (2012), 24,
OP23
3. S. Salvatore, A. Demetriadou, S. Vignolini, S.S. Oh, S. Wuestner, N.A. Yufa, M. Stefik, U. Wiesner, J.J. Baumberg, O. Hess, and U. Steiner, Adv.
Mater. (2013), 25, 2713
4. T. Atherton, BLCS 2015 Oral Presentation
P 21
Developing Conductive Organic Molecular Resists for Nanofabrication of
Insulating Materials
Dennis Zhaoa, Greg O’Callaghan
a, Owen Jones
a, Farhan Hasan
b, Karolis Virzbickas
b, Jon A. Preece
a
and Alex P. G. Robinsonb
aSchool of Chemistry, University of Birmingham, Edgbaston, Birmingham, UK
bSchool of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, UK
Electron beam lithography can be used to pattern feature smaller than 10 nm. However, reaching
this length scale has only been possible on conducting surfaces, e.g. silicon wafers. On insulating
substrate such as glass or low conductivity samples such as GaN charging limits the resolution of
electron beam lithography. Whilst photolithography can be used in some applications it is not
appropriate for low volume high value manufacture. Therefore in order to mitigate charging, and
enable the use of electron beam lithography on such
substrates it is necessary to use a discharge layer, such
as thin film of metal underneath or on top of the resist.
However, such measures limit resolution in themselves,
and can also damage device performance11
. Sub 100
nm has not been achieved for insulating materials such
as GaN and glass using electron beam lithography.
In this work we are developing resist materials that are
inherently conductive. Here we describe the synthesis
of triphenylene cored resist for use in EBL as
candidates for nanostructuring insulating materials. The
triphenylene’s liquid crystalline behaviour, delocalised
electrons and excellent electron transport make them appealing candidates to be able to not only act
as a resist, but also as a charge dissipater.
[
11] Z. Cui, Nanofabrication Principles Capabilities and Limits, 2008, 1
st ed., Berlin: Springer, 220-250
P 22
Polarization-independent switchable liquid crystal lenses based on the
dark conglomerate phase
H. Miltona, M. Nagaraj
a, S. Kaur
b, J. C. Jones
a,b, P. B. Morgan
c and H. F. Gleeson
a,b
aSchool of Physics and Astronomy, University of Manchester, Manchester M13 9PL bSchool of Physics and Astronomy, University of Leeds, Leeds LS2 9JT
cEurolens Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PL
Liquid crystal lenses are an emerging technology that can provide variable focal power in response
to applied voltage. However, an issue with many nematic liquid crystal lens designs is that they are
polarization dependent, with only 50% of unpolarised light being subject to the variable change in
focal power. This makes polarization-independent technologies very attractive. One of the ways to
achieve that is using electro-optic modes of optically isotropic materials.
Recently, the dark conglomerate (DC) phase, which is an optically isotropic liquid crystalline state,
has been shown to exhibit a large change in refractive index in response to an applied electric field
[1]. This unusual change in the refractive index which has not been reported before in the DC phase
of other liquid crystals occurs because of a series of electric-field-driven transformations that take
place in the DC phase of the studied bent-core liquid crystal. We present computational modelling
of the electrostatic solutions for two different types of 100 μm diameter liquid crystal lenses –
microlenses and flat GRIN lenses, which include the DC phase. A feature of the field dependence of
the refractive index change in the DC phase is that it is approximately linear in a certain range,
leading to the prediction of excellent optical quality for driving fields in this regime. A simulated
microlens shows two modes of operation: a positive lens based upon a uniform bulk change in
refractive index at high voltages, and a negative lens resulting from the induction of a gradient
index effect at intermediate voltages. On comparing the simulated microlenses and flat GRIN
lenses, the main difference is in the variability of focal power that can be achieved. In the case of
the flat GRIN structure, the focal power can be varied continuously between 0 D and -83.5 D, while
the microlens device chosen as an exemplar is restricted to three optical states: 0 D, -85 D, and -20
D.
The work illustrates that the DC phase has excellent potential for the development of a new class of
polarization independent switchable liquid crystal lenses.
References 1M. Nagaraj, K. Usami, Z. Zhang, V. Görtz, J. W. Goodby and H. F. Gleeson, Liq. Cryst. (2014), 41, 800.
3H. E. Milton, M. Nagaraj, S. Kaur, P. B. Morgan, J. C. Jones and H. F. Gleeson, Appl. Optics (2014), 53, 7278.
P 23
Colloid – Liquid Crystal Gels
T. A. Wood, J. S. Lintuvuori, A. B. Schofield, D. Marenduzzo, W. C. K. Poon
School of Physics and Astronomy, James Clerk Maxwell Building, University of Edinburgh, EH9 3JZ
Abstract:
Liquid crystalline materials occur in aqueous solutions of surfactant, DNA, peptide solutions, lipids
and drugs in addition to the thermotropic materials used in liquid crystal displays. In many
multicomponent biological systems and commercial formulations colloids are combined with liquid
crystalline phases – therefore it is important to understand interactions between colloids and liquid
crystals.
The nematic phase has orientational order and any defects caused by shear relax over time as the
phase equilibrates. Immersing particles within a nematic phase creates defects since the uni-
directional nematic must accommodate the surface morphology of the particle.
We examine the range of gel structures that form when hard-sphere colloids are dispersed in the
nematic phase of 5CB. Through experiments and computer simulations we show that, when the
surfaces of particles support homeotropic anchoring in a nematic solvent, colloidal structure is
sensitive to concentration. Elastic mediation results in chain-like structures at very low volume
fractions, < 2%. At intermediate volume fractions, 2% < < 22%, multi-particle clusters form
and gather to form a percolating colloidal gel. For > 22% the colloids are knitted together by
percolating lines of defects that extend through the sample and lead to high elasticity [1]. All these
structures are deeply metastable with percolating structures that persist for longer than 1 year.
Figure 1: Appearance of colloid dispersions in 5CB for different concentrations (A) in a vial after 10 months,
from left to right = 1%, 3% and 5% (B) a drop of = 3% on a slide showing heterogeneous macroscopic
texture (C) a spread drop of = 33% showing a smooth macroscopic texture. Confocal images of (D) the
chain-like structures at = 0.5%, (E) percolating colloidal clusters at = 6% and (F) a densely knitted
structure at = 33%.
P 24
The effect of a methylene link in the flexible spacer of liquid crystal dimers
Jordan P Abberley, John MD Storey and Corrie T imrie
Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, Aberdeen AB24 3UE,
UK
The twist bend nematic phase was recently identified for methylene-linked cyanobiphenyl-based
liquid crystal dimers[1,2]
and the structure confirmed in studies based on freeze fracture transmission
electron microscopy.[3,4]
In the Ntb phase, the achiral molecules form a helix and the director is tilted
with respect to the helical axis. The induced twist may be either left or right handed and equal
amounts of both types of helix are expected. The Ntb phase had previously been predicted to exist
for bent molecules by Dozov who suggested that in a nematic phase the director may bend around
bent molecules.[5]
To stabilise such a bend, either splay or twist must be introduced, resulting in two
new nematics with nonuniform director distributions, splay-bend or twist-bend.
The twist-bend nematic phase has been reported for just a small number of compounds and so the
development of the empirical relationships linking molecular structure to the observation of this
exciting new phase is at a very early stage. However, all the compounds reported to date have a bent
molecular shape, and the majority of these are dimers containing methylene-linked spacers, which
accentuate the molecular bend. It was believed that this was an essential structural feature to
observe the Ntb phase, however, an ether-linked dimer has also been shown to exhibit the phase.[6]
We recently showed that a methylene-ether linked spacer could also support the formation of the Ntb
phase and here we compare the properties of a set of compounds containing such a spacer:
with those of the corresponding ether linked materials:
The transitional properties of these materials have been determined using polarized light
microscopy and differential scanning calorimetry. The differences in their properties are attributed
to differences in their average molecular shapes.
References [1] V.P. Panov, M. Nagaraj, J.K. Vij, Y.P. Panarin, A. Kohlmeier, M.G. Tamba, R.A. Lewis, G.H. Mehl, Phys. Rev. Lett. 2010, 105, 167801.
[2] M. Cestari, S. Diez-Berart, D. A. Dunmur, A. Ferrarini, M. R. de la Fuente, D. J. B. Jackson, D. O. Lopez, G. R. Luckhurst, M. A. Perez-
Jubindo, R. M. Richardson, J. Salud, B. A. Timimi, H. Zimmermann H, Phys. Rev. E 2011, 84, 031704.
[3] V. Borshch, Y. K. Kim, J. Xiang, M. Gao, A. Jakli, V. P. Panov, J. K. Vij, C. T. Imrie, M. G. Tamba, G. H. Mehl, O. D. Lavrentovich, Nat.
Commun. 2013, 4, 2635.
[4] D. Chen, J. H. Porada, J. B. Hooper, A. Klittnick, Y. Shen, M. R. Tuchband, E. Korblova, D. Bedrov, D. M. Walba, M. A. Glaser, J. E.
Maclennan, N. A. Clark, Proc. Nat. Acad. Sci. USA 2013, 110, 15931-15936.
[5] I. Dozov, Europhys. Lett. 2001, 56, 247-253.
[6] R. J. Mandle, E. J. Davis, S. A. Lobato, C. C. A. Vol, S. J. Cowling, J. W. Goodby, Phys. Chem. Chem. Phys. 2014, 16, 6907-6915.
P 25
Application of EPR Spectroscopy and Molecular Dynamics Simulations to a
Lyotropic Liquid Crystal – A Combined Approach
Christopher Prior a and Vasily S. Oganesyan
a
aSchool of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K.
Electron Paramagnetic Resonance (EPR) with paramagnetic spin probes combined with molecular
modelling have proved to be a particular useful approach for the study of the dynamics and
molecular organisation in nematic and discotic thermotropic liquid crystals1-3
.
Here we report the first application of a combination of EPR spectroscopy and MD simulations to
sodium dodecyl sulphate (SDS) lyotropic systems doped with the 5-DOXYL stearic acid (5DS)
nitroxide spin probe. The SDS systems include pre-micellar, micellar and rod aggregations. Fully
atomistic MD simulations have been carried out using the General AMBER Force Field (GAFF)
and ChElPG scheme for partial charges and the TIP4P-Ew water model. EPR spectra are predicted
directly from these MD trajectories using our MD-EPR simulation methodology4,5
. Predicted
motions for different surfactant aggregations and the resulting EPR lineshapes show good
agreement with experiment and demonstrate the advantages of using a combined MD-EPR
approach for providing a new level of detail in molecular motions and order. In particular, the
results show that 5DS probe has anisotropic (axial) rotational correlation times, when doped in both
SDS micelles and rods, and serves as a sensitive reporter of the local molecular environment.
This study uncovers the potential for such a synergistic approach to provide information about the
changes in the sizes and motions of surfactant aggregates across the phase transition regions.
References 1. F. Chami, M. R. Wilson, V. S. Oganesyan, Soft Matter (2012), 8, 6823.
2. H. Gopee, A. N. Cammidge, V.S. Oganesyan, Agnew. Chem. Int. Ed. (2013), 52, 8917.
3. V. S. Oganesyan, E. Kuprusevicius, H. Gopee, A. N. Cammidge, M. R. Wilson, Phys. Rev. Lett. (2009), 102, 013005.
4. V. S. Oganesyan, Phys. Chem. Chem. Phys. (2011), 13, 4724.
5. V. S. Oganesyan, J. Magn. Reson. (2007), 188, 196.
Micelle
Rod
SDS
Exp.Sim. (MD)
P 26
Conductive Resists for Nanofabrication on Insulating Substrates
F. Hasan a, G. O'Callaghan
b, J.A. Preece
b, A.P.G. Robinson
a
a School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK b School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
Electron beam lithography (EBL) has the capability for extremely high-resolution patterning, mask
making for photolithography, low-volume high-value manufacturing, prototyping and other
nanotechnology research. In EBL electrons are used for patterning, therefore it is ideal to use
conductive substrates. However, if the substrate is an insulator (e.g. glass), or made with poor
conducting materials (e.g. GaN) patterns become distorted and misaligned due to the buildup of
charge in the substrate. Traditionally this issue has been treated by using a metal-coated discharge
layer under or over the resist or an organic conductor mixed into the resist. Previous studies indicate
that a conductivity of ~10-2
S/m is required to achieve acceptable charge dissipation [1].
Due to increased process complexity and poor resolution with the approaches described above, we
are developing an electron beam resist which is an inherently conductive material. Previously we
have demonstrated an epoxy derivative of triphenylene, which is highly sensitive and capable of
patterning below 20 nm feature sizes [2]. Triphenylene derivatives are well known as excellent
photoconductors [3], and due to their hexagonal columnar discotic liquid crystal structure [4] they
show fast hole mobility (e.g. 10-3
cm2V
-1s
-1) [5] along the columns. Therefore this project aims to
develop a triphenylene derivative with high conductivity and at the same time good lithographic
properties.
Initial experiments with 2,3,5,6,10,11-hexapentyloxy-triphenylene have been performed. The
material forms good quality films by spin coating on glass and silicon substrates. The sensitivity of
the material is found to be ~4 mC/cm2 without chemical amplification (CA) and a resolution of 14
nm isolated (Fig. 1) and 20 nm half pitch (Fig. 2) has been achieved on silicon substrates at 28.8
nC/cm dose in a 28 nm film. Fig. 3 shows 40 nm half-pitch with 339 pC/cm dose on a 26 nm thick
CA film and the sensitivity of this CA resist has been found 25.9 μC/cm2. Fig. 4 shows the first
patterning results on a poor conductivity substrate – a linewidth of 35 nm achieved on a nm GaN on
sapphire substrate.
Fig. 1. 14 nm pattern in a 28 nm thick film at 31.6 nC/cm dose.
P 26
Fig. 2. 20 nm half pitch lines in a 28 nm film at 28.8 nC/cm dose.
Fig. 3. 40 nm half pitch lines in a 26 nm CA film at 339 pC/cm dose.
Fig. 4. 35 nm line patterned on GaN on Sapphire at 8 mC/cm2.
References [1] M. Angelopoulos, J. M. Shaw, R. D. Kaplan, and S. Perreault, JVST B. 7 (1989) 1519.
[2] H.M. Zaid, A.P.G. Robinson, R.E. Palmer, M. Manickam and J.A. Preece, Adv. Funct. Mater., 17, 2522 (2007)
[3] F. Closs, K. Siemensmeyer, T. Frey and D. Funhoff, Liquid Crystal, 14 (1993), 629.
[4] M. T. Allen, S. Diele, K. D. M. Harris, T. Hegmann, B. M. Kariuki, D. Lose, J. A. Preece, and C. Tschierske, Journal of Materials Chemistry 11
(2001), 302-311.
[5] M. Inoue, H. Monobe, M. Ukon, V.F. Petrov, T. Watanabe, A. Kumano, and Y. Shimizu, Opto-Electronics Review, 13 (2005), 4, 303–308.
P 27
Numerical Modelling of Cholesteric Droplets
Menyang Yang, Prashant Patel, F. Anibal Fernandez and Sally Day
Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE UK
Numerical modelling has been carried out to simulate the structures of cholesteric liquid crystals
confined in droplets. The variable order modelling methods used [1,2] allow the formation and
movement of defects within the structure; the surface alignment can be set at the surface of the
droplet. Initially nematic liquid crystal were simulated in spherical and oblate droplets, with planar
degenerate anchoring at the surface of the droplet. The formation of defects at the poles of the
droplets were found and, as expected, the defects form at the regions of highest curvature in the
oblate droplets. Spherical droplets were then used to model the cholesteric structures. The twist in
the director was found to be largely uniform in one direction, but the structure in the other
directions becomes distorted. Variation in the structure with strength of surface alignment has also
been simulated. Investigation of the required number of nodes was investigated and as a result the
modelling is currently carried out on relatively small structures, but with longer simulation times
larger droplets could be modelled. The optical properties of the larger structures will show the
characteristic selective reflection.
References 1. James, R; Willman, E; Fernandez, FA; Day, SE; (2008) IEEE TRANSACTIONS ON MAGNETICS , 44 (6) 814 - 817.
2. James,R, Willman,E, Fernandez, FA and Day,SE (2006) IEEE T. Electron Devices, 53 (7) 1575-1582..
P 28
A c2mm Liquid Crystal Phase Formed by Dimer Molecules
Warren Stevenson a, Ziauddin Ahmed
b, Xiangbing Zeng
a, Goran Ungar
a and Georg Mehl
b
a Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield
b Department of Chemistry, University of Hull, Cottingham Road, Hull
In recent years the nematic – nematic transition observed in LC dimers with an odd spacer has
attracted significant attention. The theorised existence of helical chirality within the lower
temperature nematic, often termed the Nx or Ntb phase, has been the primary focus of investigation.
To date the proposed conical helices continue to elude unambiguous identification through
conventional characterisation techniques; as such we turn our attention to the liquid crystal (LC)
phases formed below the Nx. Here we present a modulated smectic c2mm LC phase formed upon
cooling the Nx phase of DTC7C5 through a first order phase transition. This phase was
characterised through grazing incidence and transmission X-ray scattering experiments which
reveal a centred rectangular unit cell (spacegroup c2mm) with lattice parameters ‘a’ = 27.21 ±
0.07nm (modulation wavelength) and ‘b’ = 4.145 ± 0.007nm (layer spacing). We propose that the
periodic step in the molecular arrangement originates from local splay in a similar fashion to the B1
banana phase of polar bent core mesogens. However in contrast to the B1 phase the step does not
create layer discontinuity, but instead produces interlocked double layers. The (11) and (02) lattice
spacing of these double layers were found to respectively coincide with the ~1.9 and ~4nm
scattering maxima observed within the Nx phase. This, as well as the similarity in POM textures,
may suggest that the two phases are in fact closely related. This work may therefore bring us a step
closer to determining the true structure of Nx phase.
(20)
(40)
(11) (31) (51)
(02)
c2mm Phase
Cooling
Nx Phase
1.89nm
3.98nm
P 29
An isothermal nematic to twist-bend nematic phase transition
Daniel A. Paterson, A. Martinez-Felipe, R. Walker, J. M. D. Storey, and C. T. Imrie
Department of Chemistry, University of Aberdeen, Meston Walk, AB24 3UE, UK.
The twist-bend nematic phase (Ntb) has recently been observed in liquid crystal dimers which
consist of molecules in which two mesogenic units are separated by an odd-membered methylene-
linked flexible spacer1. In the Ntb phase, the achiral molecules form a helix and the director is titled
with respect to the helical axis. The Ntb phase had previously been predicted to exist for bent
molecules by Dozov and its formation attributed to a bend elastic constant (K33) which tends
towards zero2.
Recently molecules containing ether linkages in the spacer have been found to exhibit twist-bend
nematic behaviour3,4
. This prompted us to consider methylene-ether linked spacers and these also
support the formation of the Ntb phase5. Here we report the synthesis and charcterisation of a dimer
containing an azobenzene moiety linked to a cyanobiphenyl unit by a methylene-ether flexible
spacer:
The dimer exhibits two mesophases; the lower temperature mesophase is the twist-bend nematic
phase attributed to the bent shape of the molecule; whilst the higher temperature is assigned as a
typical nematic phase. An isothermal Ntb - N phase transition is observed on photoisomerising the
azo linkage in the dimer.
Figure 1. CB6OABOBu
Figure 2. Ntb phase exhibited by CB6OABOBu at 105 °C
References 1. Cestari, M., Diez-Berart, S., Dunmur, D. A., Ferrarini, A., de la Fuente, M. R., Jackson, D. J. B., Lopez, D. O., Luckhurst, G. R., Perez-
Jubindo, M. A., Richardson, R. M., Salud, J., Timimi, B. A., and Zimmerman, H., 2011, Phys. Rev. E, 84, 031704.
2. Dozov, I., 2001, Europhys. Lett., 56, 247.
3. Mandle R. J., Davis E. J., Lobato S. A., Vol C. C. A., Cowling S. J., Goodby J. W. PCCP. 2014;16(15):6907-6915.
4. N. Sebasti´an, D. O. L´opez, B. Robles-Hern´andez, M. R. de la Fuente, J. Salud, M. A. P´erez-Jubindo, D. A. Dunmur, G. R. Luckhurst
and D. J. B. Jackson, Phys. Chem. Chem. Phys., 2014, 16, 21391–21406.
5. Jansze S. M., Martinez-Felipe A., Storey J. M. D., Marcelis A. T. M., Imrie C. T., Angew. Chem. Int. Ed. 2015;54(2):643-646.
Sponsors
The British Liquid Crystal Society and Sheffield Hallam University are very
grateful to the sponsors, who have helped make this conference possible. Please
take a moment to look through the services our sponsors can provide for you.
Merck KGaA Frankfurter Straße 250 64293 Darmstadt Germany Tel.: +49 (0) 6151 72-0 Fax: +49 (0) 615172-2000
Taylor & Francis Customer Services Bookpoint 130 Milton Park Abingdon Oxon OX14 4SB UK Tel: +44 (0) 1235 400 524 Fax: +44 (0) 1235 400 525 Email (UK Trade): [email protected]
Kingston Chemicals Limited Department of Chemistry University of Hull Hull HU6 7RX UK. Tel: +44(0)1482465866 Fax: +44(0)1482466410 www.hull.ac.uk/kingston-chemicals/
Conference booklet for the 29th
annual British Liquid Crystal Society conference
http://blcs.eng.cam.ac.uk/
Sheffield Hallam University Faculty of Arts, Computing, Engineering & Sciences Materials & Engineering Research Institute (MERI) Howard Street Sheffield S1 1WB UK Tel: +44 (0)114 225 3500 Fax: +44 (0)114 225 3501 Email: [email protected]
www.shu.ac.uk/research/meri/
