SIDE-CHAIN LIQUID-CRYSTALLINE POLYOXETANES WITH A SPACER-SEPARATED AZOBENZENE MOIETY .2. PREPARATION AND CHARACTERIZATION OF POLYOXETANES DERIVED FROM 4-(4-ALKOXYPHENYLAZO)PHENYL [7-(3-METHYL-3-OXETANYL)-1,6-DIOXAHEPTYL]BENZOATES

A series of polyoxetanes were prepared by the cationic ring-opening po lymerization of 4-(4-alkoxyphenylazo)phenyl [7-(3-methyl-3-oxetanyl)-1 ,6-dioxaheptyl]benzoates using 0.08 molar amount of THF . BF3 in dichl oromethane at 20 to 30 degrees C. Although the product polymers indica ted GPC-average molecular weights of around 9000 to 23000, in most cas es, they did not have an unimodal molecular weight dispersity. The liq uid-crystalline mesophases of the polymers were examined by differenti al scanning calorimetry and polarized optical microscopy; these textur es were observed due to nematic and/or smectic mesophases over a wide temperature range from about 250 degrees C to room temperature. The be nzoate moiety, the longer p-substituted alkoxy tails, and the oxetane main chain play important roles in maintaining highly ordered, stable mesophases.