Structures and properties of cholesteric liquid crystalline elastomers

The synthesis of new side-chain cholesteric liquid crystalline elastomers containing mesomorphic crosslinking agent M-1 and cholesteric monomer M-2 was described by a one-step hydrosilylation reaction. The chemical structures of the obtained network polymers were confirmed by FT-IR spectroscopy. The mesogenic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction measurements. The mesomorphic crosslinking agent was adopted to diminish the disturbance of the non-mesogenic crosslinking agent on liquid crystalline elastomers. The influence of the crosslinking units on the phase behavior was discussed. The liquid crystalline elastomers P-2-P-6 containing less than 10.8 mol% crosslinking agent showed elasticity, reversible phase transition, and cholesteric grandjean texture. The experimental results demonstrated that the glass transition temperatures and the isotropization temperatures of the networks polymers decreased a little with increasing concentration of crosslinking units but the cholesteric phase was not disturbed.