PREPARATION OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS VIA PYRIDYL-PHENOL HYDROGEN-BONDING

A series of side-chain liquid-crystalline polymers via pyridyl-phenol hydrogen bonding complexation was prepared by using non-liquid-crystal line precursors, such as poly[(4-vinylpyridine)-co-(butyl acrylate)] a nd 4-(4'-nitrophenylazo)phenol, 4-(4'-methoxyphenylazo)phenol or 4-(ph enylazo)phenol The association by hydrogen bonding was confirmed by me ans of FTIR. While the hydrogen bonds are weakened, and some dissociat ion occurs at the isotropization temperature, complete dissociation ne eds much higher temperature. The hydrogen bonds re-form as the complex is cooled to room temperature. The nematic liquid crystallinity of th e polymer complexes was shown by means of wide-angle X-ray diffraction (WXRD) and polarized optical microscopy (POM). The different substitu tion groups of azophenol give isotropization temperatures of the polym er complexes in the following sequence: -NO2 > -H > -OCH3.