SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS CONTAINING THE SILOXANE SPACER.5. SYNTHESES AND THERMAL-PROPERTIES OF COPOLYMETHACRYLATES WITH DIFFERENT SPACER STRUCTURES

Copolymerizations of the methacrylate-type monomers whose spacer consi sted of only alkylene unit with the comonomers containing a disiloxane unit in the spacer component were carried out by radical polymerizati on. The effects of copolymer composition and structure of mesogen on t he mesomorphic properties of the obtained copolymers were investigated , using DSC, optical polarizing microscope and X-ray diffractometry. T (g) and T(i) of the copolymers decreased with increase in comonomer co mponent reflecting the flexibility of the siloxane linkage. The introd uction of the comonomer containing a siloxane spacer and a laterally a ttached mesogen was effective to lower the temperature range of the me sophase. The copolymers, of which the comonomer content was about 50 m ol%, exhibited an enantiotropic nematic phase, whereas the parent homo polymers exhibited a smectic phase. Consequently, the mesophase and te mperature range of liquid crystalline state could be controlled by the introduction of a comonomer unit containing a siloxane spacer.