作者:K. Rózga-Wijas、J. Chojnowski、M. Ścibiorek、W. Fortuniak
DOI:10.1039/b501833c
日期:——
1,1,1,7-Tetramethoxy-3,3,5,5,7,7-hexamethyl-1,3,5,7-tetrasiloxane TMOS-D3} and 1,1,1,7-tetramethoxy-3,5,7-trimethyl-3,5,7-trivinyl-1,3,5,7-tetrasiloxane TMOS-V3} were made, respectively, by cationic telomerisation of hexamethylcyclotrisiloxane (D3) or 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane (V3) with tetramethoxysilane (TMOS). These compounds were used as precursors of siloxaneâsilica materials. Their structure resulted in the generation of short trisiloxane segments which were well dispersed in the formed hybrid framework. These precursors or their mixtures with TMOS were subjected to solâgel polycondensation in dispersions or in bulk catalysed by NaOH. Siloxaneâsilica hybrid materials were obtained either in the form of precipitated particles (1â80 µm) of various regular or irregular shapes or in the form of a monolithic material disintegrated on drying. In the solâgel dispersion process, which was performed in the presence of a surfactant, cetyltrimethylammonium bromide, almost all methyl groups were converted to oxygen bridging two silicon atoms while in the bulk process a small fraction of unreacted alkoxyl and hydroxyl groups remained in the gel. Materials obtained from pure TMOS-D3} and TMOS-V3} showed a very low porosity and surface area. In contrast, particles having a high surface area can be obtained from mixtures of these new precursors and TMOS. Gels prepared from TMOS-V3} and its mixture with TMOS were subjected to hydrosilylation with HMe2SiCl and the silylated particles were used for grafting of a living polysiloxane polymer.
1,1,1,7-四甲氧基-3,3,5,5,7,7-六甲基-1,3,5,7-四硅氧烷TMOS-D3}和1,1,1,7-四甲氧基-3 ,5,7-三甲基-3,5,7-三乙烯基-1,3,5,7-四硅氧烷TMOS-V3}分别通过六甲基环三硅氧烷(D3)或2,4,6-三甲基的阳离子调聚制备-2,4,6-三乙烯基环三硅氧烷 (V3) 与四甲氧基硅烷 (TMOS)。这些化合物被用作硅氧烷-二氧化硅材料的前体。它们的结构导致产生短的三硅氧烷链段,这些链段很好地分散在形成的杂化框架中。这些前体或其与 TMOS 的混合物在分散体中或在 NaOH 催化下进行本体溶胶-凝胶缩聚。硅氧烷-二氧化硅杂化材料要么以各种规则或不规则形状的沉淀颗粒(1-80μm)的形式获得,要么以干燥时分解的整体材料的形式获得。在溶胶凝胶分散过程中,该过程在表面活性剂十六烷基三甲基溴化铵的存在下进行,几乎所有甲基都转化为桥接两个硅原子的氧,而在本体过程中,一小部分未反应的烷氧基和羟基保留在凝胶。由纯TMOS-D3}和TMOS-V3}获得的材料表现出非常低的孔隙率和表面积。相反,具有高表面积的颗粒可以从这些新前体和TMOS的混合物中获得。用HMe2SiCl对由TMOS-V3}及其与TMOS的混合物制备的凝胶进行氢化硅烷化,并且将硅烷化颗粒用于活性聚硅氧烷聚合物的接枝。