Two series of mainchain liquid crystalline polysiloxane polyurethane elastomers(that is biphenyl type and azoxybenzene type) were synthesized. The structure and properties of these polymers were characterized by FT-IR

DSC

DMA and polarization microscope. Our study concluded that most of these polyurethane samples exhibited nematic thermotropic liquid crystal character. The liquid crystal properties had strong relations with the interaction between the hard and soft segments of the block polyurethane.