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Smectic behaviour of linear random copolymers containing the stilbene‐4,4′‐dicarboxy group

1986; Wiley; Volume: 187; Issue: 9 Linguagem: Inglês

10.1002/macp.1986.021870909

0025-116X

Cosimo Carfagna, Antonio Roviello, Salvatore Santagata, Augusto Sirigu,

Photochromic and Fluorescence Chemistry

Abstract Copolymeric systems of the general formula: P 1 = {((OCH 2 CH 2 ) a OR) m ((OCH 2 CH 2 ) b OR) n } x or P 2 = {((OCH 2 CH 2 ) a OR) m (O(CH 2 ) b OR) n } x with R = OCC 6 H 4 CHHCC 6 H 4 CO were prepared and their mesophasic properties studied by polarizing microscopy, differential scanning calorimetry and X‐ray diffraction analysis. Enantiotropic smectic mesomorphism was directly observed in most cases. For all systems but P 2 ( a = 2, b = 12) a single smectic phase was observed for all compositions, with a continuous variation of the smectic structural periodicity, isotropization temperatures and molar entropic changes close to the weighted average. This indicates a complete compatibility of the different monomer units in the formation of the smectic layers. On the contrary, system P 2 ( a = 2, b = 12) exhibits two smectic phases each within a definite range of composition. The two phases are sharply distinct as far as the structural periodicity is concerned. Both phases are present in the mesophasic state of copolymer with m = 75.