基烯基结构对单核和双核有机介导的乙烯聚合物的影响:同时引入多烯基分支和功能组的范围和机制
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|February 21, 2007
概括
在有机催化烯聚合过程中,基西兰酸盐作为链转移剂和共体,产生高度分支的多聚烯,具有高活性和狭窄的多分散性.
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
- 材料科学 材料科学 材料科学
背景情况:
- 有机复合物是烯聚合物的有效催化剂.
- 控制聚合物架构,例如长链分支,对于定制材料特性至关重要.
- 基西兰具有作为功能单体和链转移剂的潜力.
研究的目的:
- 为了研究基西兰素作为同时链转移剂和在有机中介乙烯聚合中的共体的作用.
- 评估基链长度和 (Ti) 核度对聚合活性,共聚合物组成和分支的影响.
- 探索链转移的机制及其对催化剂结构和基基结构的依赖.
主要方法:
- 使用激活的单核 (CGCTiMe2) 和双核 (EBICGCTi2Me4) 有机预催化剂进行乙烯聚合.
- 包括各种基基 (基,3-基基,5-基基,7-基基) 作为链转移剂和共同体.
- 使用诸如凝透色谱-多角度激光光散射 (GPC-MALLS) 等技术对聚合物产品进行表征,以确定分子量,多分散性和分支.
主要成果:
- 实现了高的聚合活性 (高达107 g/mol Ti·atm·h)) 和狭窄的共聚合物聚散度.
- 观察到大量的长链分支,而长链基基基烯的分支比接近1.0.
- 基化的合并因链长和Ti核度而异,单核系统的合并率更高.
- 核性影响了分子量和基基度之间的关系,表明了不同的链转移机制.
结论:
- 基西兰是有效的双重功能剂,可合成长链分支聚烯.
- 选择Ti催化剂的核度和基结构显著影响聚合结果.
- 这种方法提供了一条前所未有的途径,通过单步共聚合过程精确控制多烯结构.
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