Theoretical Aspects of Controlled Radical Polymerization in a Dispersed Medium
Theoretical Aspects of Controlled Radical Polymerization in a Dispersed Medium
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分散介质中受控自由基聚合的理论问题
DOI：
10.1021/ma0002904
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发表时间：
2000
期刊：
影响因子：
5.5
通讯作者：
B. Charleux
中科院分区：
文献类型：
--
作者：
B. Charleux
在分散介质中，当持续自由基效应起作用时，研究了可控自由基聚合（CRP）的动力学。为此，硝基氧化物介导的CRP被认为是在具有油溶性烷氧胺单分子引发剂的微乳液体系中，并且在没有热自引发的情况下。提出了不可逆终止速率随粒径变化的解析表达式，并与体积终止速率进行了比较。根据这些表达式，计算了氮氧化物释放浓度随单体转化的变化规律。对于大颗粒，聚合动力学发现在散装和在微乳液相似。相比之下，对于小颗粒，由于终止速度较慢，释放的氮氧化物浓度在微乳液中比在散装中更小，从而导致死链比例更低，聚合速度更快，摩尔质量分布更宽。
Kinetics of controlled radical polymerization (CRP) is examined in a dispersed medium, when the persistent radical effect operates. For that purpose, nitroxide-mediated CRP is considered in a miniemulsion system with oil-soluble alkoxyamine unimolecular initiator and in the absence of thermal self-initiation. An analytical expression of the rate of irreversible termination is proposed as a function of particle size, and it is compared with the rate of termination in bulk. From these expressions, the evolution with monomer conversion of the concentration of released nitroxide is calculated. For large particles, the polymerization kinetics was found to be similar in bulk and in the miniemulsion. In contrast for small particles, owing to slower terminations, the concentration of released nitroxide was shown to be smaller in the miniemulsion than in bulk, leading thus to a lower proportion of dead chains, a faster polymerization, and a broader molar mass distribution.