Polymerization of Dendritic Macromonomer and Preparation of its membrane for Permseparation

树枝状大分子良好的侧链结构有望对高选择性膜的渗透选择性起到重要作用。我们采用聚合法合成了以叔丁基、三甲基硅基或低聚二甲基硅氧烷为外围基团的树枝状苯乙炔单体。这些单体在末端乙炔单元用Rh催化剂聚合，得到相应的聚苯乙炔的黄色粉末，聚合度很高，例如，DP=2.8×10^3，尽管它们是空间膨胀的。尽管单树的空间体积较大，但仍能获得高相对分子质量的多树，其原因可能有以下几点。末端乙炔从树枝状分子中暴露出来，聚合反应按立体规则进行，从而使侧链树枝状分子合理堆积。该聚合物可溶于氯仿、四氢呋喃等常见有机溶剂，不溶于醇，且其溶解性优于相应的零生成聚苯乙炔衍生物。聚合物的广角X射线散射表明其为棒状分子的伪六方晶格。晶面间距d随着外围硅基的生成或大小的增加而增加。结果表明，树枝状聚合物具有良好的成膜能力，并考察了膜的气体透过性。与相应的零生成聚苯乙炔衍生物相比，该多枝状化合物的氧渗透选择性表现出良好的性能。研究发现，树枝状结构和棒状结构对膜的选择有很好的作用。

The well-defined side-chain structure of dendrimers is expected to play an important role on the permselectivity for highly selective membranes. We synthesized dendritic phenylacetylene monomers containing tert-butyl group, trimethylsilyl group, or oligodimethylsiloxane, as the peripheral group using the convergent approach. The monomers were polymerized with rhodium catalyst at the terminal acetylene unit to yield the corresponding poly(phenylacetylene) derivatives as yellow powders with a high degree of polymerization, e.g., DP=2.8 x 10^3, in spite of their steric bulkiness. Some reasons why the monodendrons gave the polydendrons with high molecular weight in spite of their steric bulkiness were probably considered as follows. The terminal acetylene was exposed from dendritic crowd, and the polymerization proceeded stereoregularly to give the reasonable packing of the side-chain dendrons. The polymers were soluble in common organic solvents, such as chloroform and tetrahydrofuran, but insoluble in alcohols, and the solubility of these polydendrons was better than that of the corresponding zero generation poly(phenylacetylene) derivatives. The wide angle X-ray scattering of the polymers suggested the pseudohexagonal lattice of rod-like molecules. The interplanar d spacing increased with increasing generation or size of the peripheral silyl group. The polydendrons indicated good membrane forming ability, and the gas permeability of the membrane was examined. The oxygen permselectivity of the polydendrons showed good performance in comparison with the corresponding zero generation of poly(phenylacetylene) derivatives. It was found that the well-defined dendritic and rod-like structure of the polydendrons was useful for pemselective membrane.