摘要
考察三甲基铝(TMA) 部分水解法制备固体改性甲基铝氧烷(m MAO) 时,反应物H2O 和TMA 的摩尔比对m MAO 的产量及m MAO 中TMA 含量的影响;以五甲基茂基三苄氧基钛[Cp * Ti(OBz)3]/m MAO 组成的均相催化体系,分别考察m MAO 的用量[ 即Al/Ti 摩尔比] 及m MAO 中TMA 含量对苯乙烯间规聚合和乙烯聚合的影响.通过分析Cp * Ti(OBz)3/m MAO 催化体系钛氧化态的分布,发现Ti( Ⅲ) 活性中心有利于合成间规聚苯乙烯;而Ti( Ⅳ) 活性中心有利于合成聚乙烯.苯乙烯间规聚合时,外加三异丁基铝(TIBA) ,将提高催化活性,同时可节省MAO 用量.
Syndiotactic polystyrene (sPS) and polyethylene were comparatively synthesized with homogeneous catalytic systems composing η\+5 \|pentamethycyclopentadienyltribenzyloxy titanium \[Cp\+*Ti(OBz)\-3\] and various modified methylaluminoxanes (mMAO).The content of TMA in mMAO can be controlled by regulating H\-2O/TMA molar ratio during the preparation of mMAO by partial hydrolysis of TMA with Al\-2(SO\-4)\-3·18H\-2O.The effect of Al/Ti molar ratio on polymerization of styrene as well as ethylene have been studied in detail. The oxidation states of titanium in Cp\+*Ti(OBz)\-3/MAO catalytic systems were determined by redox titration method. It seems that active centre of Ti(Ⅲ) is favorable for styrene syndiospecific polymerization with higher catalytic activity, while Ti(Ⅳ) center is favorable for ethylene polymerization. The styrene syndiospecific polymerization may also be influenced by the external addition of tri\|isobutyl\|aluminum(TIBA) into the same catalytic sistem giving higher yield but slightly lower molecular weight of sPS.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2000年第1期41-45,共5页
Acta Polymerica Sinica
基金
国家自然科学基金!( 基金号2934010)
广东省自然科学基金!资助项目( 基金号960803)
关键词
茂钛金属催化剂
甲基铝氧烷
聚苯乙烯
聚乙烯
Titanocene catalyst, Methylaluminoxane, Styrene syndiospecific polymerization, Ethlyene polymerization