Synthesis of silylated polyolefin with well-defined chain structure and the application to a surface modifier

采用活性阴离子聚合法合成了含1，4-聚丁二烯和1，4-聚（2-三异丙氧基硅基-1，3-丁二烯）链段的嵌段共聚物。用仲丁基锂引发的阴离子活性聚异戊二烯在庚烷中与叔丁醇钾在THF中反应以转化增长物种。2-三异丙氧基硅基-1，3-丁二烯与活性聚异戊二烯的连续聚合得到具有所需明确链结构的嵌段共聚物。用威尔金森催化剂对嵌段共聚物进行加氢，得到含硅基的嵌段聚烯烃。采用溶胶-凝胶法制备了粒径为200-600 nm的SiO2微粒，并将其与硅烷化聚烯烃（SiO2）进行改性，在180 ℃下与线性低密度聚乙烯（LLDPE）共混，用扫描电镜观察了共混物的断面形貌。二氧化硅珠粒的表面完全被聚合物覆盖。相反，未改性的二氧化硅珠粒和LLDPE的共混物的断裂表面具有透明珠粒，其不粘附到聚合物基质。这些结果表明，硅烷化聚烯烃通过硅氧烷键固定在二氧化硅表面上，并且附着在表面上的聚乙烯链段与LLDPE相容。

The block copolymer containing 1,4-polybutadiene and 1,4-poly(2-triisopropoxysilyl-1,3-butadiene)segments was synthesized by living anionic polymerization. The anionic living polyisoprene initiated with sec butyllityium in heptane was allowed to react with potassium tertbutoxide in THF to transform the propagating species. The sequential polymerization of 2-triisopropoxysilyl-1,3-butadiene with the resulting living polyisoprene to afford the block copolymer with desired well-defined chain structure. The hydrogenation of the block copolymer with Wilkinson catalyst gave the block polyolefin containing silyl groups. The small silica particle(200-600 nm diameter)was prepared by sol-gel method, which was modified with the silyated polyolefin and mixed with linear low density polyethylene(LLDPE) at180ﾟC.The fractured surface of the blend was observed by scanning electronic microscopy. The surface of the silica bead was completely covered with polymer. On the contrary, the fractured surface of the blend of the unmodified silica bead and LLDPE had clear beads, which did not adhered to the polymer matrix. These results suggest that the silylated polyolefin is fixed onto the silica surface tyrough siloxane linkage and that polyethylene segment attached to the surface is compatible with LLDPE.