含腈基的液晶制备和性能研究

AbstractChiral side-chain liquid-crystalline polymers were graft copolymerized by usingpoly(methylhydrogeno)siloxane,a cholesteric monomer (Mi)cholesteryl4-(undecen-1-yloyloxy)benzoateandanematicmonomer4-(undecy-1-yloxybenzoyloxy)-4-benzonitrile (M2).The chemical structures andliquid-crystalline properties of the monomers and polymers were investigated by FTIR,H-NMR,DSC and POM measurements.The results showed the structures of themonomers and polymers were in good agreement with the target structures.The monomerMi exhibited a cholesteric phase on heating,and showed a cholesteric-blue phase transitionon cooling.However,monomer M2 only exhibited a nematic phase both on heating andcooling.All the polymers revealed cholesteric phases with wide mesophase temperatureranges and lower glass transition temperatures.The isotropic phase transition temperaturesand glass transition temperatures of the polymers decrease with the increase of nematicmesomorphic phase in the polymer systems.Meanwhile,the mesophase temperature rangesof polymers decreased.Key words:liquid-crystalline polymers;cyanogen;liquid crystal phase behavior;poly(methylhydrogeno)siloxane2