CHIRAL PALISADE SIDE-CHAIN LIQUID-CRYSTAL COPOLYMERS - EFFECT OF COMONOMER END-GROUP ON THE NATURE OF THE LIQUID-CRYSTALLINE PHASE

Three series of copolymers were prepared from 4-[2-(S)-methyl-3-acrylo xy)-4'-methoxy phenyl] benzoate, as the common chiral monomer, and thr ee nonchiral 4-alkyloxy phenyl-4'-(6-acryloxy hexyloxy) benzoates with alkyloxy tail groups containing seven to nine atoms. All of the copol ymers exhibited liquid crystalline (LC) behavior over the entire compo sition ranges studied. It was demonstrated that by changing the length of the alkyloxy unit, significant differences could be induced in the LC phases observed. When the alkyloxy unit was seven atoms long only chiral nematic (N) phases were detected, whereas lengthening the alky loxy unit to eight and nine atoms led to the formation of smectic A (S -A) and chiral smectic C (S-c()) phases in addition to the N-* phase. Films of these materials exhibited selective reflection in the visibl e region as one would expect from the presence of N- and S-c(*) phase s. (C) 1998 John Wiley & Sons, Ltd.