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Synthesis of side‐chain liquid‐crystalline polyesters using diethyl malonates with a mesogenic group and oligo(ethylene glycol)s and effect of specific interactions on their mesogenic behavior
Author(s) -
Kodaira Toshiyuki,
Endo Mitsuhiko,
Kurachi Masato
Publication year - 1998
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/(sici)1521-3935(19981001)199:10<2329::aid-macp2329>3.0.co;2-g
Subject(s) - mesogen , monomer , polymer chemistry , copolymer , ethylene glycol , polymer , liquid crystal , side chain , chemistry , materials science , crystallography , organic chemistry , liquid crystalline , optoelectronics
Side‐chain liquid‐crystalline polymers were synthesized using malonic acid esters with a mesogenic group ( 1 ) linked through a hexamethylene spacer and oligo(ethylene glycol) ( 2 n ) as a flexible mainchain spacer. Polymers derived from 1 with a mesogen such as p ‐nitrophenylazophenoxy ( 1a ) or 4‐(4′‐nitrophenylvinylene)phenoxy group ( 1b ) form stable mesophases over a wide temperature range, through the increase of chain length of 2 n decreases the thermal stability of the liquid‐crystalline (LC) phases. LC polymers were obtained from 1 with a mesogen with p ‐substituted biphenoxy groups only when 2 n with shorter chain length is employed. Copolymerizations were undertaken to see the effect of monomer pairs and copolymer compositions on the phase transition behavior of the copolymers formed, using three monomer pairs, 1a and 1 with the p ‐methoxybiphenoxy group as the mesogen, 1a and 1b , and 1a and 1 with the p ‐nitrobiphenoxy group as the mesogen. The copolymers formed from the first pair display a nematic phase over a much wider temperature range than the respective homopolymers. This was ascribed to the electron donor‐acceptor interaction between the two mesogens in the monomer pair.