Synthesis and characterization of side‐chain liquid‐crystalline elastomers containing cholesterol

A series of new smectic and cholesteric liquid-crystalline elastomers were prepared by graft polymerization of mesogenic monomer with the chiral and nonmesogenic crosslinking agent using polymethylhydrosiloxane as backbone. The chemical structures of the monomers and polymers obtained were confirmed by Fourier transform infrared and proton nuclear magnetic resonance spectra. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction measurements. M1 showed cholesteric phase during the heating and the cooling cycle. Polymer P1, elastomers P2 and P3 exhibited smectic phase, elastomers P4P6 showed chiral smectic C phase, P7 showed cholesteric phase, and P8 displayed stress-induced birefringence. The elastomers containing less than 15 mol % M2 displayed elasticity and reversible phase transition with wide mesophase temperature ranges. Experimental results demonstrated that the glass transition temperatures, the isotropization temperatures, and the mesophase temperature ranges decreased with increasing content of the crosslinking unit. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 383–390, 2005