A NEW-TYPE OF MAIN-CHAIN LIQUID-CRYSTAL POLYMER-DERIVED FROM 4'-HYDROXYBIPHENYL-4-CARBOXYLIC ACID AND ITS SMECTIC MESOPHASE BEHAVIOR

A homologous series of polymers (PHBC-n) has been prepared from 4'-hydroxybiphenyl-4-carboxylic acid and omega-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.