Eur. Phys. J. E 6, 277-285 (2001)

Structure and frustration in liquid crystalline polyacrylates I. Bulk behaviour

B.I. Ostrovskii^{1, 2}, S.N. Sulyanov², N.I. Boiko³, V.P. Shibaev³ 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
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.

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