DMPC on mica

Phospholipid monolayer

water subphase

Gleiche et al., Nature 2000, 403,173-175

DPPC on mica

Transfer direction

Chen et.al., JPCB, 110 (2006) 8041

(Out of equilibrium states)

B. Pignataro et al., J. Phys. Chem. B 111 (2007) 9189

DPPC on mica

Derivatized Flavonoids

B. Pignataro, unpublished

J. Huang, Nanoletters 6 (2006) 524-529

Au Nanoparticles

O. Purrucker, JACS 127 (2005) 1258

Cell Receptors

20 mm/min 60 mm/min

2 mm/min 7 mm/min 10 mm/min

(temperature 10 °C, surface pressures 30 mN/m)

(Ageing of the ordered molecular surfaces)

15 days under airImmidiatly after transfer

Different patterns can be found in Nature showing periodic structures along with anisotropy and fractal pathways. Also as to fluids, instability at the propagation front has been observed in gravity-driven falling films (viscous fingering) or in rising films under a temperature gradient. Moreover, by considering the preparation of functional materials, regular patterns are common features in directional solidification. In this case such a patterns originates from different drivers including heat flows, mass diffusion gradients, uniaxial stresses, or lattice mismatches, as in heteroepitaxy. These patterns are induced by instability effects and typically extend in the same direction of the moving front with periodicity ranging from millimeters (gravity forces) to microns (temperature gradients).

Patterns in Nature and instabilities

Viscous fingering

Gravitational instabilities

Solidification instabilities

M.Bestehorn et al, Phys. Rev. Lett. 2001

Flow on an inclined planemm scale

P. Moraille et al., Langmuir 2002

10 µm x 10 µm , height scale 3 nm

LB mixed monolayer

No gravity, intermolecular and surface forces !!

Height modulation of the incompressible water layer (surface tension < substrate-surfactant)

substrate

subphasemonolayer

Substrate-surfactant forces density fluctuation

condensedexpanded

Instabilities are stronger at the three-phase contact line (stronger substrate-surfactant interaction)

Solid Substrate

H2O

Subs

trat

e-su

rfac

tant

per

pend

icul

ar f

orce

Distance from the three-phase contact line

Low speed

High speed

Original front

New front

Perpendicularpattern

Parallel pattern

Sur

fact

ant C

once

ntra

tion

(P

ress

ure)

Transfer Speed

0.5

0

Isotropic/Random

PeriodicParallel

PeriodicPerpendicularTr

ansi

tion

regi

on

Compact

A. Raudino, B. Pignataro, Journal of Physical Chemistry B (Letter) 111 (2007) 9189