Side-Chain Liquid-Crystalline Polyoxetanes with a Spacer-Separated Azobenzene Moiety. III. Preparation and Characterization of Polyoxetanes Anchoring the Mesogen Cores of a<i>p</i>-Spacer-Substituted Phenyl 4-(4-Alkoxyphenylazo)benzoate in the Side Chain
作者:Hiroshi Ogawa、Shigeyoshi Kanoh、Masatoshi Motoi
DOI:10.1246/bcsj.70.1649
日期:1997.7
Polyoxetanes anchoring the mesogen cores of p-spacer-substituted phenyl 4-(4-alkoxyphenylazo)benzoates through a pendant spacer, –CH2O(CH2)4O–, were prepared by a BF3-initiated cationic ring-opening polymerization of the corresponding oxetanes, followed by a fractional reprecipitation of the raw polymer products containing oligomer fractions. The polyoxetanes separated from the oligomers had their peak tops at molecular weights of around 10000—23000 in nearly mono- or dimodal molecular-weight dispersity curves determined by gel permeation chromatography, and indicated fan-shaped textures due to a smectic mesophase over a wide temperature range from about 250 °C to room temperature on heating and cooling processes by polarized optical microscopy. The formation of highly ordered assemblies of the pendant mesogens is ascribable to a cohesion of the 4-(4-alkoxyphenylazo)benzoate moiety in the mesogen core, which can form a larger dipole, due to forming a longer conjugated system from the ester carbonyl to the alkoxy tail, than that of the simple 4-alkoxybenzoate moiety of the mesogen core previously reported by us.
通过 BF3 引发相应氧杂环丁烷的阳离子开环聚合,然后对含有低聚物馏分的原始聚合物产品进行分馏再沉淀,制备出了锚定了对间隔物取代的苯基 4-(4-烷氧基苯基偶氮)苯甲酸酯中间体核心的聚氧杂环丁烷。从低聚物中分离出来的聚氧乙烯在凝胶渗透色谱法测定的分子量分散曲线中,分子量峰值约为 10000-23000 左右,在加热和冷却过程中,偏振光显微镜显示出从约 250 °C 到室温的宽温度范围内由于胶凝介相而形成的扇形纹理。悬垂介聚物形成高度有序的集合体是因为介聚物核心中的 4-(4-烷氧基苯基偶氮)苯甲酸分子具有内聚力,与我们之前报道的介聚物核心中简单的 4-烷氧基苯甲酸分子相比,这种内聚力可以形成更大的偶极,因为它形成了从酯羰基到烷氧基尾部的较长共轭体系。