SIDE-CHAIN LIQUID-CRYSTALLINE POLYOXETANES WITH A SPACER-SEPARATED AZOBENZENE MOIETY .3. PREPARATION AND CHARACTERIZATION OF POLYOXETANES ANCHORING THE MESOGEN CORES OF A P-SPACER-SUBSTITUTED PHENYL 4-(4-ALKOXYPHENYLAZO)BENZOATE IN THE SIDE-CHAIN

Polyoxetanes anchoring the mesogen cores of p-spacer-substituted pheny l 4-(4-alkoxyphenylazo)benzoates through a pendant spacer, -CH2O(CH2)( 4)O-, were prepared by a BF3-initiated cationic ring-opening polymeriz ation of the corresponding oxetanes, followed by a fractional reprecip itation of the raw polymer products containing oligomer fractions. The polyoxetanes separated from the oligomers had their peak tops at mole cular weights of around 10000--23000 in nearly mono- or dimodal molecu lar-weight dispersity curves determined by gel permeation chromatograp hy, and indicated fan-shaped textures due to a smectic mesophase over a wide temperature range from about 250 degrees C to room temperature on heating and cooling processes by polarized optical microscopy. The formation of highly ordered assemblies of the pendant mesogens is ascr ibable to a cohesion of the 4-(4-alkoxyphenylazo)benzoate moiety in th e mesogen core, which can farm a larger dipole, due to forming a longe r conjugated system from the ester carbonyl to the alkoxy tail, than t hat of the simple 4-alkoxybenzoate moiety of the mesogen core previous ly reported by us.