Synthesis and liquid crystalline properties of azobenzene-containing poly(vinyl ether)s with narrow molar mass distribution

摘要

A series of new liquid crystalline (LC) poly(vinyl ether)s with different molar masses was synthesized via a two-step procedure involving the preparation of functional matrices by living cationic polymerization of an ω-chloroalkyl vinyl ether monomer followed by a grafting reaction of an azobenzene mesogenic unit onto them. By appropriately adjusting the experimental conditions, it was possible to predetermine the molar mass characteristics of the LC polymers. Each of the parent and modified poly(vinyl ether)s had a narrow molar mass distribution. The LC polymers were semicrystalline and formed a nematic mesophase, enantiotropic or monotropic in character. The transition temperatures increased with increasing molar mass up to a limiting value and then remained nearly constant. Accordingly, poly(vinyl ether)s with predetermined molar mass and narrow molar mass distribution could be prepared.