Synthesis and characterization of sidechain liquid cryastalline polysiloxanes containting either cholesteryl or cyanobiphenyl mesogenic groups

A series of side-chain liquid crystalline polysiloxanes containing either cholesteryl or cyanobiphenyl mesogenic groups were synthesized by the hydrosilylation reaction of a polysiloxane containing Si−H group with a vinyl-terminated compound containing the mesogenic group. Their chemical structures were confirmed by IR,¹H NMR, and elemental analysis, Their phase behaviors were investigated by differential scanning calorimetry, optical polarizing microscope, and X-ray diffraction technique. The results show that all these polysiloxanes except P V display smectic or nematic mesonorphism or both. The dependence of phase transition temperature on the rigidity of mesogenic unit. the length of spacer group, and the flexibility of chain is also described. Supported by the National Natural Science Foundation of China Xu Guangwei: born in June 5, 1970, Postgraduate