用新型茂钛催化剂制备的苯乙烯/丁二烯嵌段共聚物的结构表征

用CpTi(OBz)3/MAO催化体系合成的苯乙烯／丁二烯嵌段共聚合产物经丁酮、甲苯、四氢呋喃、氯仿连续抽提，并用已烷对丁酮的可溶级分进行再抽提；不同级分分别用GPC、^13C -NMR、DSC和WAXD等手段进行分析和表征。发现嵌段共聚物主要存在于氯仿可溶级分中，丁酮可溶级分基本上是无规聚苯乙烯和聚丁二烯组成的混合物（己烷可溶级分为聚丁二烯，不溶级分为无规模聚乙烯）。GPS谱图表明该嵌段共聚反应具有单催化活性中心的聚合特征，^13C-NMR谱图显示该嵌段共聚物分子链由间规聚苯乙链段和聚丁二烯链段组成，WAXD图谱显示嵌段共聚物有较高的结晶度。

Charactezrization of Styrene/Butadiene Block Copolymer with Cp*Ti(OBz)3/MAO Catalyst

The block copolymerization of styrene/butadiene was carried out by using a catalytic system of (5 pentamethylcyclopentadienyltribenzyloxy titanium Cp *Ti(OBz) 3] and methylaluminoxane (MAO). The copolymerization products were fractionated by successive solvents extraction with boiling butanone, toluene, THF and chloroform. The block copolymer, chiefly exsisting in the cholroform soluble fractions of the products, was isolated and characterized by GPC, 13 C NMR, DSC and WAXD methods. The total copolymers are confirmed to be the mixture of polybutadiene(PBd), atactic polystyrene (aPS), syndiotactic polystyrene (sPS) and. syndiotactic polystyrene b polybutadiene copolymer. According to GPC spectrum, the block copolymerization is mono catalytic specie copolymerization. 13 C NMR spectrum showed that block copolymer molecular chain is made up of syndiotactic styrene chain and polybutadiene chain. WAXD indicated that block copolymer had higher crystallinity degree.