Eur. Phys. J. E 6, 277-285 (2001)
Structure and frustration in liquid crystalline polyacrylates I. Bulk behaviour
B.I. Ostrovskii1, 2, S.N. Sulyanov2, N.I. Boiko3, V.P. Shibaev3 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
3 Moscow State University, Department of Chemistry, Moscow, 119899 Russia
dejeu@amolf.nl
(Received 28 February 2001 and Received in final form 6 August 2001)
Abstract
The phase behaviour and structure are reported of a new type of frustrated
side-chain liquid crystalline (LC) polymer, a polyacrylate with
phenylbenzoate mesogenic side groups and a narrow polydispersity. At a high
degree of polymerisation the LC polymers show a nematic, a smectic-A,
a re-entrant nematic and a
phase, for shorter chains only
a nematic and a
phase. This constitutes a new example of
nematic re-entrance for which the driving field is the length of the polymer
chain. The smectic-A
layers consist of partially overlapped side
groups while in the
phase the side chains are rearranged into
chevron-like blocks of bilayers. We propose an explanation of the frustrated
phase behaviour in terms of these two different competing length scales and
their coupling to the backbone conformations.
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