Chiral palisade side-chain liquid crystal copolymers: Effect of comonomer end group on the nature of the liquid crystalline

Three series of copolymers were prepared from 4-[2-(S)-methyl-3-acryloxy)-4'-methoxy phenyl] benzoate, as the common chiral monomer, and three nonchiral 4-alkyloxy phenyl-4'-(6-acryloxy hexyloxy) benzoates with alkyloxy tail groups containing seven to nine atoms. All of the copolymers exhibited liquid crystalline (LC) behavior over the entire composition ranges studied. It was demon-strated 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 alkyloxy 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 visible region as one would expect from the presence of N* and S_C* phases. © 1998 John Wiley & Sons, Ltd.