使用 (III) 化物对D,L-乳化物的立体选择性聚合的机制研究
Agostino Pietrangelo1, Spencer C Knight, Aalo K Gupta
1Department of Chemistry and Center for Sustainable Polymers, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota, 55455-0431, USA.
Journal of the American Chemical Society
|August 3, 2010
概括
这项研究详细介绍了使用化启动剂的种族乳酸的立体选择性聚合,实现了受控的聚合物生长并探索了反应动力学. 这些发现揭示了立体控制的机制及其对其他循环的适用性.
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:
- 乳化物的受控聚合对于生产具有量身定制性质的可生物降解聚合物至关重要.
- (III) 化合物已成为环开聚合的有希望的催化剂.
- 了解种族乳酸的立体选择性聚合是控制聚合物微观结构的关键.
研究的目的:
- 研究由化 (InCl3) 启动的种族乳酸 (D,L-LA) 的立体选择性和受控的聚合.
- 为了阐明聚合动力学,并确定活跃的发起物种.
- 探索负责立体控制的机制以及该系统对其他循环的范围.
主要方法:
- 使用InCl(3),醇 (BnOH) 和三乙烯胺 (NEt(3) 在位启动剂制剂.
- 动力学研究以确定与发起体,酒精和单体有关的反应顺序.
- 使用元素分析,X射线晶体学,NMR和FTIR光谱学对复合物的表征.
- 脉冲梯度旋回回声 (PGSE) 核磁共振来确定启动复合体的溶液结构.
主要成果:
- 通过分子量和单体转化/度比之间的线性关系证明了受良好控制的聚合.
- 在InCl中发现的聚合动力学是第一阶的(3) 和BnOH和NEt的零阶的(3).
- D,L-LA转化率取决于 (III) 化物和乳化物立体异构体,表明立体选择性.
- 发起物种的标识为双核复合体,[InCl(3)(deapH)(H(2) O) ](2) 或其无水形式.
结论:
- 使用基于InCl(3) 的启动器系统实现了D,L-LA的新型立体选择和受控聚合.
- 拟议的机制合理化了观察到的立体控制,涉及双核复合体.
- 该InCl(3) /BnOH/NEt(3) 系统是有效的聚合其他循环,包括epsilon-caprolactone.
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