Radical Polymerization of Methyl Methacrylate in the Presence of Cobaloximes and Benzoyl Peroxide
Radical Polymerization of Methyl Methacrylate in the Presence of Cobaloximes and Benzoyl Peroxide
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钴肟和过氧化苯甲酰存在下甲基丙烯酸甲酯的自由基聚合
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发表时间：
1992
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通讯作者：
A. Gridnev
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作者：
A. Gridnev
研究了钴肟（LCo）催化甲基丙烯酸甲酯（MMA）自由基聚合的动力学和单体上的链转移。含量高达40%v/v的非极性溶剂不影响动力学和分子量分布（MWD）的聚MMA。在MMA中加入1- 5%v/v的极性溶剂，DMF和其它酰胺、DMSO和吡啶在聚合的初始阶段提高了自由基还原LCo（III）（催化剂的失活状态）到LCo（II）（催化剂的活性状态）的速率，但不改变链转移催化（CTC）的速率。本体MMA和含极性溶剂的MMA的还原被证明是一个自催化过程。LCo（III）还原的起始速率常数范围为200 ~ 3000 m− 1 s −1，取决于乙醛肟配体的取代基。过氧化苯甲酰和过氧化氢异丙苯在MMA聚合介质中氧化LCo（II）为LCo（III），反应速率常数约为0.001。10 M− 1 s −1，因此过氧化物通过发现的规则降低了钴肟的催化活性，提供了一种新的四氯化碳控制方法。在苯乙烯（St）的情况下，过氧化苯甲酰会导致钴肟的不可逆中毒。
The kinetics and inherent chain transfer on a monomer in radically polymerizing methyl methacrylate (MMA) by cobaloxime (LCo) catalysis in the presence of chemical substance of various types are described. Nonpolar solvents at content up to 40% v/v do not influence kinetics and molecular-weight distribution (MWD) of polyMMA. The addition of 1–5% v/v of polar solvents in MMA, e.g., DMF and other amides, DMSO and pyridine enhances the rate of reduction of LCo(III) (inactivated state of catalyst) to LCo(II) (active state of catalyst) by radicalas at initial stage of polymerization but does not change the rate of chain transfer catalysis (CTC). The reduction in bulk MMA and MMA containing polar solvents is proved to be an autocatalytic process. Starting rate constants of LCo(III) reduction ranged from 200 to 3000 m−1s−1 depending on the substitute at glyoximato ligands. Benzoyl peroxide and cumyl hydroperoxide were found to oxidize LCo(II) to LCo(III) in polymerizing MMA medium at a rate constant ca. 10 M−1s−1 and thus peroxides decline titled catalytic activity of cobaloximes by discovered rules providing a new way of CTC control. In the case of styrene (St) the benzoyl peroxide causes irreversible poisoning of cobaloximes.