SYNTHESIS AND PHASE-BEHAVIOR OF LIQUID-CRYSTALLINE POLYESTERS DERIVEDFROM P,P'-BIBENZOIC ACID AND MESO AND R-3-METHYLHEXANEDIOL

The synthesis and thermal properties of two new Liquid crystalline pol yesters derived from bibenzoic acid and (R,S)- or (R)-3-methyl-1,6-hex anediol are reported. The phase behaviour was investigated by means of differential scanning calorimetry, X-ray diffraction and polarizing m icroscopy. The effect of the asymmetry introduced by the branched meth yl group and that of the stereoisomerism on the type and stability of the mesophases formed are analysed. Both polymers exhibited smectic me sophases of different types depending on thermal history. The presence of an optically active pure diol along the chain gives rise to a more regular structure in comparison with the polymer synthesized from the racemic mixture. (C) 1998 Published by Elsevier Science Ltd. All righ ts reserved.