极性乙烯基单体的催化剂现场控制的协调聚合,使其成为高合成性聚合物
Yuetao Zhang1, Yalan Ning, Lucia Caporaso
1Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA.
Journal of the American Chemical Society
|February 4, 2010
概括
这项研究强调了一种新型的催化剂,用于从极性乙烯基单体 (如甲基甲酸 (MMA)) 制造高合成性聚合物. 优化的催化剂在聚合反应中表现出卓越的活性,效率和立体控制.
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:
- 极性乙烯基单体的协调聚合具有挑战性,因为单体的反应性和催化剂的兼容性.
- 金属催化剂提供了受控聚合的潜力,但需要仔细的连接体和金属中心设计.
- 在极性乙烯基单体聚合物中实现高立体选择性,特别是协同作用性是关键目标.
研究的目的:
- 为了研究极性乙烯基单体的催化剂场所控制的协调聚合.
- 识别和优化金属催化剂系统,用于生产高合成性聚合物.
- 阐明聚合过程的动力学,机械学和理论基础.
主要方法:
- 合成和选12个C(s) 结合的安萨-cyclopentadienyl (Cp) -R(2) E(C,Si) -fluorenyl (Flu) 4组金属催化剂.
- 甲基甲基酸盐 (MMA) 聚合的动力学和机械学研究.
- 理论/计算研究使用密度函数理论 (DFT) 支持机械学建议.
主要成果:
- 阴离子安萨-金属乙烯乙烯酸催化剂6在MMA聚合 (1554h-1TOF,94% rr综合性,1.14MW分布) 中表现出优异的性能.
- 提出了一种由催化剂现场控制的单金属协调添加机制,涉及乙烯酸酸中间体.
- 该系统在广泛的温度范围内表现出恒定的协同触动性,对溶剂极性和离子结构不敏感.
结论:
- 优化的金属催化剂可实现高效和立体选择性合成综合性PMMA.
- 聚合采用一种独特的催化剂位点控制的机制,与单体辅助的表聚合相结合.
- 催化剂桥梁结构显著影响立体选择性,而刚性桥梁提高了性能.
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