DIELECTRIC RELAXATIONS OF A SIDE-CHAIN LIQUID-CRYSTAL HOMOPOLYMER ANDCOPOLYMER

The dielectric loss spectrum of a side chain liquid crystal polymer (S CLCP) has been measured from 10 Hz to 100 kHz in the smectic phase. Th ree liquid crystalline siloxane polymers are examined, a homopolymer a nd two random copolymers, all of which contain a chiral smectic mesoge n and an eleven-methylene spacer in the side chain. Two dielectric rel axations have been observed, the high-frequency alpha and low-frequenc y delta processes. The effect of the copolymer morphology in these SCL CPs is to increase the dielectric relaxation strength of the delta pro cess relative to the cc process and to cause increased overlap between the two peaks. These two observations suggest that the copolymer stru cture aids large scale reorientations in the delta process because of increased cooperativity with the backbone.