Synthesis and characterisation of chiral liquid crystalline elastomers containing four-arm crosslinking agent.

A new series of side-chain chiral liquid crystalline elastomers derived fromM1(cholest-5-3-ol(3β)-4-(2-propen-yloxy)]benzoate) andMC(2,5-[3,5-bis(4-(3-(4-(allyloxy)phenyl)propanoyloxy)benzoyloxy)benzoic acid]isosorbide diester). The structures of monomers and elastomers measured by using Proton Nuclear Magnetic Resonance Spectra (1H-NMR) and Fourier transform infrared spectroscopy (FTIR) separately are consistent with our design.IIP~VIPall appeared blue Grandjean (GJ) texture on the heating cycle or cooling cycle. The glass sheets ofIIP~VIPwere made under 150°C and measured its ultraviolet–visible spectrophotometry by PerkinElmer Lambda 950 instrument (Shelton, CT, USA).IIP~VIPall have absorptions at about 481~483 and 561~562 nm. The optical activities were measured at different temperatures on heating and cooling cycles. And the blue selective reflection ofIIP~VIPon the round glass sheet can be seen. The elastomers containing less than 6 mol% of the crosslinking units displayed elasticity, reversible phase transition and high thermal stability. The glass transition temperatures reduced first and then increased, the isotropisation temperatures and the mesophase temperature ranges increased first and then decreased with increasing content of crosslinking unit. The thermogravimetric analysis (TGA) results showed that the temperatures at which 5% weight loss occurred (Td) were greater than 310°C for all the polymers. [ABSTRACT FROM AUTHOR]