在活生生的自由基聚合过程中,长寿命的中间基具有一致的实验和理论证据
Achim Feldermann1, Michelle L Coote, Martina H Stenzel
1Centre for Advanced Macromolecular Design, School of Chemical Engineering and Industrial Chemistry, The University of New South Wales, Sydney, NSW 2052, Australia.
Journal of the American Chemical Society
|December 2, 2004
概括
库米尔二硫酸盐 (CDB) 介导的可逆添加碎片化链转移 (RAFT) 聚合显示出延迟的稳定状态行为. 这支持了跨终结的缓慢碎片化模型,表明RAFT附加基作为动力沉降器.
科学领域:
- 聚合物化学 聚合物化学
- 物理化学 物理化学
- 计算化学的计算化学
背景情况:
- 可逆加法碎片化链转移 (RAFT) 聚合是一种受控的激素聚合技术.
- 了解RAFT聚合的机制对于控制聚合物结构和特性至关重要.
- 昆二硫酸盐 (CDB) 是本研究中使用的一种特定RAFT药物.
研究的目的:
- 通过实验和计算方法研究CDB介导的styrene的聚合动力学.
- 为了区分RAFT聚合的缓慢碎片化和交叉终结模型.
- 确定拟议的机械参数的物理现实性.
主要方法:
- 进行了动力实验,以监测聚合过程的进展.
- 使用高水平的ab initio分子轨道计算来建模反应路径和能量.
- 进行了详细的动力分析,考虑了前平衡,主要平衡和链长度依赖.
主要成果:
- 动力学数据显示,稳定状态行为出现延迟,与交叉终结模型不一致.
- 缓慢碎片化模型准确地描述了当假定有很大的碎片化常数时的实验数据.
- 最初的计算支持慢碎片化模型所需的高平衡常数的物理现实性.
- 据计算,RAFT附加基的寿命大约为2.5秒.
结论:
- 这项研究提供了强有力的证据,支持CDB介导的烯RAFT聚合的缓慢碎片化模型.
- 交叉终结模型无法全面解释观察到的运动行为.
- RAFT附加基是动力稳定的,并作为有效的基沉积器起作用,有助于控制的聚合.
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