Eur. Phys. J. E 6, 287-294 (2001)

Structure and frustration in liquid crystalline polyacrylates II. Thin-film properties

B.I. Ostrovskii^{1, 2}, D. Sentenac¹, I.I. Samoilenko² and W.H. de Jeu<sup>1

1</sup>  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.

PACS
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