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New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
} if time
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Topological defects: lines and walls
• Lattice Boltzmann simulations
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
Continuum / Phase Field Models for Complex Fluids
Isothermal Navier Stokes fluid:
Additional stress S depends on internal degrees of freedom
Continuum / Phase Field Models for Complex Fluids
Isothermal Navier Stokes fluid:
Additional stress S depends on internal degrees of freedom
Binary fluid mixtures (emulsions):
Scalar composition f
Continuum / Phase Field Models for Complex Fluids
Isothermal Navier Stokes fluid:
Additional stress S depends on internal degrees of freedom
Binary fluid mixtures (emulsions):
Scalar composition f
Liquid crystals:
Orientational alignment tensor Q na
Continuum / Phase Field Models for Complex Fluids
Equations of motion for internal fields:
Additional stress
Liquid crystal:
S describes rotation of rodlike objects in flow
Additional stress S: complicated but known
Free energy functional F is known in both cases
na
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
Lattice Boltzmann Method for Forced NSE
• each site x has velocity set {ci}: ci t = lattice vector
• fi(x,t): population of fluid “particles” at x with velocity ci
(x,t) = ∑i fi fluid density v(x,t) = ∑i fi ci fluid velocity
• local streaming, and relaxation
fi(x+ci,t+1) – fi(x,t) = ∑j Lij (fj(x,t) – fj
0(x,t)) F.cfi • continuum limit: forced Navier Stokes equation
• select
Complex Fluids: Hybrid Lattice Boltzmann
Couple LB to finite difference code for f, Q dynamics
Read in required velocity field from LB
Update order parameters via FD
Pass stress to LB as NSE solver
D. Marenduzzo, E. Orlandini, MEC, J. Yeomans, PRE 76, 031921 (2007)
et seq.
LUDWIG Parallel coding and curation: K. Stratford, O. Henrich (Edinburgh)
https://ccpforge.cse.rl.ac.uk/gf/project/ludwig/
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
fluid-fluid phase separation: domain walls
defect core
proliferating disclination lines in chiral liquid crystal
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
Colloidal Inclusions Spherical hard particles; no slip boundary conditions Energetics: particles attracted to topoplogical defects Physics: covering up the defect saves energy!
fluid interface disclination line
both cases:
Colloidal Inclusions Additional Physics
fluid interface: wettability
liquid crystals: anchoring
q
defaults: q = p/2 no anchoring
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
Designing New Materials by Computer Binary fluid phase separation + colloidal particles Concept: • Coarsening interfaces sweep up particles
• Particles form jammed monolayer: coarsening stops
• Percolating 2D layer rigidifies entire structure
• Bicontinuous Interfacially Jammed Emulsion Gel = Bijel MEC et al. Patents 2005, K. Stratford et al, Science 2005
Designing New Materials by Computer Binary fluid phase separation + colloidal particles Concept: • Coarsening interfaces sweep up particles
• Particles form jammed monolayer: coarsening stops
• Percolating 2D layer rigidifies entire structure
• Bicontinuous Interfacially Jammed Emulsion Gel = Bijel MEC et al. Patents 2005, K. Stratford et al, Science 2005
without colloids with colloids
BIJELS – Bicontinuous interfacially jammed emulsion gels
BIJELS – Bicontinuous interfacially jammed emulsion gels
Bijels: Confocal Microscopy Confocal Microscopy M. Reeves et al, PRE 2015
robust, waxy material tricontinuous fluid/fluid/solid
Bijels: Timeline Computational proof-of-concept; patents 2005 K. Stratford et al. Science 2005 First lab realization 2007 E. Herzig et al. Nature Materials 2007 Reliable fabrication, templating 2011 J. Tavacoli et al Adv. Func. Materials 2011, Lee and Mohraz, Adv. Materials 2011 Extended range of solvent pairs, particles 2011-2016 M. N. Lee et al Adv. Func. Materials 2013 + ongoing Sample production for Li-ion battery research 2012- now J. Thijssen, P. Bruce et al. (Oxford-Edinburgh collaboration)
Bijels for Batteries Li-ion / Li-air batteries: mobile phones to electric cars anode / electrolyte /cathode Tricontinuity: Conduction paths for cations, anions, electrons Soft solid: Electrodes expand/contract on charge / discharge
research continues...
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
Bistable (powerless) Liquid Crystal Displays
Bistable LC displays
each pixel: two metastable defect configurations
power used only to switch, not maintain
supermarket display tags (ZBD), e-paper, etc.
microfabricated
substrate: defect anchor
Bistable LC displays
each pixel: two metastable defect configurations
power used only to switch, not maintain
supermarket display tags (ZBD), e-paper, etc.
microfabricated
substrate: defect anchor
Can bistability be achieved by self-assembly alone?
Colloids in Blue Phases
Fast-switching device properties of BPs
W. Cao et al, Nat Mat (2002)
can we add bistability?
Phase diagram of cholesteric liquid crystals
t temperature
k chirality zero field: e = 0
BPIII: amorphous lattice O. Henrich et al PRL 2011
BPI,II: Ordered lattices of disclinations
ISOTROPIC
CHOLESTERIC
(defect free)
Colloids in BPI/II: Weak anchoring
Numerical energy minimization
Colloids replace energy “hotspots” of pre-existing structures
M Ravnik, J. Yeomans et al., PNAS (2011)
Colloids in BPI: Full dynamics
Initial state: isotropic phase, 1% colloids
Quench into BPI
weak anchoring on particles strong
lock-in of metastable amorph
K. Stratford et al Nature Comms (2014)
Colloids in BPI: Confined system
slab geometry, 1% colloids
top
side
weak anchoring on particles strong
K. Stratford et al Nature Comms (2014)
Colloids in BPI: Confined system
Slab geometry; 4% colloids
top
side
weak anchoring on particles strong
K. Stratford et al Nature Comms (2014)
Colloids in BPIII
K. Stratford et al Nature Comms 5, 3954 (2014)
Colloids in BPIII: external field
K. Stratford et al Nature Comms 5, 3954 (2014)
Colloids in BPIII: field switching+ bulk multistability
no field field on field off (showing particles only)
K. Stratford et al Nature Comms 5, 3954 (2014)
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
Active Liquid Crystals Oriented phase of self-propelled fibres Inspired by the cytoskeleton: polymerizable actin filaments + myosin motors Synthetic versions: “cell extracts” e.g. microtubule bundles: Dogic group, Nature 2014 Catalytic colloidal nanorods in fuel bath Sen group, JACS 2004
etc
Active Liquid Crystals Oriented phase of self-propelled fibres Inspired by the cytoskeleton: polymerizable actin filaments + myosin motors Standard equations for polar liquid crystal (P replaces Q) + 2 active terms:
Active Liquid Crystals Oriented phase of self-propelled fibres Inspired by the cytoskeleton: polymerizable actin filaments + myosin motors Standard equations for polar liquid crystal (P replaces Q) + 2 active terms:
P = <ni>
Active Liquid Crystals Oriented phase of self-propelled fibres Inspired by the cytoskeleton: polymerizable actin filaments + myosin motors Standard equations for polar liquid crystal (P replaces Q) + 2 active terms: contractile stress in fibres
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....
Cell Crawling in Eukaryotes
Keratocyte on glass
Biomimetic /modelling agenda: • polar LC emulsion droplet • self-advection in wall layer • contractile stress everywhere • anchoring at drop interface • no slip of fluid at wall
Active emulsion droplet emulates crawling cell
E. Tjhung et al, Nat Comms (2015)
Morphological Zoo
keratocyte on glass:
lamellipodium one of several shapes
static fried egg phagocytic cup
lamellipodium filopod
Morphological Zoo
immobile platelet lamellipodium
cup-like pseudopod
E Tjhung et al, Nat Comms (2015)
Morphological Zoo
immobile platelet lamellipodium
cup-like pseudopod
strong anchoring
low motor activity
just right
E Tjhung et al, Nat Comms (2015)
New Materials By Design
• Continuum / phase field models of emulsions and liquid crystals
• Lattice Boltzmann method
• Topological defects: walls and lines
• Colloidal particles + their defect interaction
• Bijels: possible battery materials
• Particle-doped liquid crystals: possible display materials
• Biomimetic media: active liquid crystals
• Crawling emulsion droplets
Collaborators: D Marenduzzo, K Stratford, I Pagonabarraga, R Adhikari, J Lintuvuori, E Tjhung, G Foffi, A Tiribocchi, O Henrich....