EFFECTS OF THE DEGREE OF SUBSTITUTION ON THE PROPERTIES AND STRUCTURES OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANES

oly[6-(4-cyanobiphenyl-4'-oxy)-hexylmetylsiloxanes (PCS-n) with variou s degrees of substitution (DS) were prepared. and the effects of the d egree of substitution on the phase transition, structures, and liquid crystallization of PCS-n were investigated. PCS-n showed S-Ad in the t emperature range from glass transition temperature (T-g) to clearing t emperature (T-i) in spite of various DS. T-g and T-i increased linearl y with DS, and the temperature range of S-A phase between T-g and T-i expanded with DS. The layer spacing d(L) of the S-A structure decrease d with increasing DS, since the non-mesogenic flexible backbones were squeezed between smectic layers. d(L) of the sample with lower DS high ly decreased with increasing temperature, due to entropy relaxation of backbones between the S, layers. DS remarkably influenced the liquid crystallization of PCS-n. PCS-n with higher DS exhibited faster growth rates of liquid-crystalline textures compared with lower DS.