齐尔科诺催化烯聚合:一个灭流动动学研究
Fuquan Song1, Roderick D Cannon, Manfred Bochmann
1Wolfson Materials and Catalysis Centre, School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
Journal of the American Chemical Society
|June 19, 2003
概括
这项研究表明,只有很小一部分安萨-金属催化剂能积极聚合,而2,1-regioerrors显著导致休眠物种的形成. 了解这些休眠状态对于优化聚合动力学至关重要.
科学领域:
- 聚合物化学 聚合物化学
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
背景情况:
- 安萨金属是基聚合的关键催化剂,但它们的机械细节,特别是关于活跃与休眠物种的细节,仍然不完全理解.
- 催化剂物种在活性链生长和休眠状态之间的分布显著影响聚合动力学和效率.
研究的目的:
- 通过使用两个不同的安萨-金属烯催化剂系统,研究烯聚合的动力学.
- 阐明基本的机械学方面,包括催化剂启动,链式传播速率和休眠物种的性质.
- 为了确定催化剂结构和聚合率之间的定量相关性.
主要方法:
- 利用灭流技术研究不同和催化剂度下的烯聚合动力学.
- 使用了两个催化剂系统: (SBI) ZrMe2/Al(i) Bu3/[Ph3C][CN[B(C6F5)3]2]和 (SBI) ZrCl(2) /甲基 (MAO).
- 分析的聚合物产量 (Y) 与反应时间 (t) 相比,以及聚合物分子重量的数值平均演变.
主要成果:
- 这两种催化剂系统都表现出对烯和conocene 度的第一级依赖.
- 确定了看似链增长率常量 (k,p,app),显示只有大约8%的总催化剂在两个系统的链增长中积极参与.
- 与MAO系统相比,酸盐系统显示相对于启动的传播速度明显更快 (k(p) /k(i) ≈6000) ≈800).
结论:
- 2,1-在烯插入中的区域错误被确定为连锁终结和休眠物种的形成的主要原因,即使在短的反应时间.
- 链增长的能量受到对抗离子的性质的强烈影响,这表明关联的离子对起着作用.
- 尽管活性有差异,但活性催化剂物种的比例保持一致,这凸显了金属催化剂中休眠物种的重要性.
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