SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS CONTAINING SILOXANE SPACER .3.THERMAL-PROPERTIES OF COPOLYMERS CONTAINING DIFFERENT TYPES OF MESOGENS

Copolymerization of monomers containing the disiloxane unit in the spa cer component and linear triple-core mesogens with comonomers containi ng linear double-core mesogens, or laterally attached triple-core meso gens was carried out radically. The effect of copolymer composition an d monomer structure on the mesomorphic properties of the obtained copo lymers was investigated in detail. The copolymers with a comonomer con tent up to 50 mol-%, exhibit an enantiotropic nematic phase, whereas t he parent homopolymers containing triple-core mesogens exhibit a smect ic phase. The copolymer containing more than 50 mol-% of the comonomer shows no mesophase. The isotropization temperature of the copolymers decreases with increasing comonomer content. However, the glass transi tion temperature is almost unchanged upon introduction of the comonome r unit. In case of copolymers containing laterally attached mesogens, a smectic phase was observed below the temperature range of the nemati c phase. Consequently, the mesophase and the temperature range of the liquid-crystalline state can be controlled by the introduction of the comonomer unit whose parent homopolymer does not exhibit any mesophase .