Synthesis and mesomorphic properties of fishbone-like liquid crystalline polysilsesquioxanes V. Pd-coordinating, fishbone-like azo-based liquid crystalline polysilsesquioxanes

作者：Youzhi Wan, Lei Xu, Lingling Ren, Lijuan Zhang · 发表于：Liquid Crystals · 年份：1998 · DOI：10.1080/026782998206696 · 被引用次数：18 · 研究领域：Silicone and Siloxane Chemistry、Synthesis and properties of polymers、Polymer Nanocomposites and Properties

New kinds of Pd-coordinating azo-based liquid crystalline polysilsesquioxanes, Pd-H-FBA and Pd-C-FBA, have been synthesized first by hydrosilylation reactions of a vinyl-terminated mesomorphic azo compound with ladder-like homopolyhydrosilsesquioxane (H-T) and copolymethylhydrosilsesquioxane (MH-T) to produce fishbone-like, azo-based liquid crystalline polysilsesquioxanes H-FBA and C-FBA, respectively, followed by a further ortho -palladation reaction with palladium chloride. The mesomorphic properties have been investigated by DSC, optical polarizing microscopy and temperature-variable X-ray diffraction. It is found that their clearing temperatures, Tcl, are much higher and the mesophase ranges, Delta T,are much wider than those of the corresponding comb-like polymers with a single main chain by more than 100 C. This indicates that the double main chain structures of the title polymers have a positive effect on mesomorphic properties. The influence of the contents of Pd2 ions on the liquid crystallinity is also discussed.