Eur. Phys. J. E 6, 287-294 (2001)
Structure and frustration in liquid crystalline polyacrylates II. Thin-film properties
B.I. Ostrovskii1, 2, D. Sentenac1, I.I. Samoilenko2 and W.H. de Jeu11 FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands
2 Institute of Crystallography, Academy of Sciences of Russia, Leninsky pr. 59, Moscow, 117333 Russia
dejeu@amolf.nl
(Received 28 February 2001 and Received in final form 6 August 2001)
Abstract
We report on the thin-film behaviour of a polyacrylate with phenyl benzoate
mesogenic side groups and a narrow polydispersity. Depending on the degree
of polymerisation, these polymers show a nematic, a smectic-A
, a
re-entrant nematic and a
phase with a two-dimensional
monoclinic lattice. X-ray reflectivity and atomic-force microscopy have been
used to characterize the structure and surface morphology. The system
exhibits two stable side-chain packing configurations with incommensurate
spacings that can be both stabilized at a free surface. Thin films in the
nematic phase show a structural dewetting induced by the growth of surface
domains of the
phase. Additionally, surface-induced ripples
with a nanoscale lateral period form at the air-film interface. We
attribute these patterns to a coupling between the local liquid crystalline
ordering of the mesogenic side groups and the surface curvature energy.
64.70.Md - Transitions in liquid crystals.
78.70.Ck - X-ray scattering.
61.30.Eb - Experimental determinations of smectic, nematic, cholesteric, and other structures.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001
