A new type of main-chain liquid-crystal polymer derived from 4′-hydroxybiphenyl-4-carboxylic acid and its smectic mesophase behaviour

Abstract

A homologous series of polymers (PHBC-n) has been prepared from 4′-hydroxybiphenyl-4-carboxylic acid and ω-bromoalkan-1-ols containing five to nine methylene units which can serve as mesogen and flexible spacer groups, respectively. The PHBC-n polymers are characterized by having two different linkage groups, ether and ester groups, to connect the biphenyl mesogen to the methylene spacer, and are classified on a new type of main-chain liquid-crystal polymer. All polymers exhibit the enantiotropic smectic phase. The smectic behaviour and structure were examined by differential scanning calorimetry, optical microscopic and X-ray diffraction methods, and are discussed in comparison with the corresponding date of the BB-n polyesters, which include only the ester linkage group.