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Liquid‐crystal behaviour of some laterally substituted stiffchain polyesters containing 2‐phenylbenzoxazole units
Author(s) -
Centore Roberto,
Roviello Antonio,
Sirigu Augusto,
Kricheldorf Hans R.
Publication year - 1994
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1994.021950827
Subject(s) - polymer , liquid crystal , stacking , phase (matter) , polyester , polymer chemistry , materials science , liquid crystalline , crystallography , side chain , crystal (programming language) , chain (unit) , chemistry , organic chemistry , composite material , physics , optoelectronics , astronomy , computer science , programming language
The synthesis and the phase behaviour of three laterally substituted stiff‐chain polymers containing 2‐phenylbenzoxazole units is reported. Polymers were obtained by reaction of 2‐(4‐acetoxyphenyl)‐6‐acetoxybenzoxazole with 2‐phenoxyterephthalic acid (polymer 2a ), 2‐phenylthioterephthalic acid (polymer 2b ) and 2‐hexadecylthioterephthalic acid (polymer 2c ). Polymers 2a and 2b are virtually non‐crystalline. 2a is nematogenic, while for 2b a smectic‐like liquidcrystal phase is observed, whose structural periodicity is probably connected with the intercalated stacking of the lateral phenyl groups along the direction of the chain axes. The solid phase of 2c is of the sanidic type. On melting, a liquid‐crystal phase with equatorial periodicity is observed. This periodicity is probably related to the segregation of the stiff chains between the paraffinic layers.