Eur. Phys. J. E 6, 277-285 (2001)
Structure and frustration in liquid crystalline polyacrylates I. Bulk behaviourB.I. Ostrovskii1, 2, S.N. Sulyanov2, N.I. Boiko3, V.P. Shibaev3 and W.H. de Jeu1
1 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
(Received 28 February 2001 and Received in final form 6 August 2001)
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