负载卤化镍(NiX2/HD)催化MMA的原子转移自由基聚合

以负载卤化镍(NiX2/HD)为催化剂合成聚甲基丙烯酸甲酯(PMMA),具有反应可控、后处理简单且催化剂可以反复使用的优点。研究结果表明:卤原子、催化剂、钝化剂的类型和含量、反应温度等条件对该体系的聚合速率及可控性有重要影响。在相同条件下,NiCl2较NiBr2的催化速率快;钝化剂卤化铜/三-(N,N-二甲基氨基乙基)胺(CuX2/Me6TREN)对聚合产物分子量分布的可控性要优于卤化铁/三-(N,N-二甲基氨基乙基)胺(FeX3/Me6TREN);增大钝化剂的含量,聚合速率降低,且含量为1%时聚合的可控性较好;温度升高聚合速率加快,分子量分布指数(PDI)增大。顺磁共振检测中观察到钝化剂中过渡金属的化合价发生改变。

Atom Transfer Radical Polymerization of MMA Catalyzed by Hybrid Supported Nickel Catalyst

The synthesis of polymethyl methacrylate(PMMA) by atom transfer radical polymerization with supported NiX_2 as catalyst has several advantages such as controllable reaction,simple treatment after polymerization and the catalyst can be reused.The result of the research shows that the reaction conditions such as temperature,type and content of halogen atom and deactivator have great effect on the polymer controllability and reaction rate.Under the same condition,the polymerization rate with supported NiCl_2 is faster than that with supported NiBr_2.And compared with deactivator FeX_3/Me_6TREN,CuX_2/Me_6TREN has better controllability on the polymerization.The rate of the polymerization decreases with the increase of the content of the deactivator.The best controllability of the polymerization is obtained when the content of the deactivator is 1%.The(polymerization) rate and polymer distribution index(PDI) increase with the reaction temperature.Based on the importance of the deactivator,the mechanism of deactivator was analyzed.The variation of the chemical valence of the transition metal was observed by EPR.However,the further(research) on the chemical valence variation of the transition metal nickel is necessary.