甲基丙烯酸甲酯的反向原-子转移自由基聚合反应研究

在较低的温度(60℃)和较低的AIBN/CuCl~2/配位剂摩尔比(1:2:4)条件下,用乙腈为溶剂,实现了甲基丙烯酸甲酯(MMA)的反向原子转移自由基聚合(RATRP)。联二吡啶(bpy)为配位剂时,所合成的聚甲基丙烯酸甲酯(PMMA)的分子量分布可低至1.08。用1,10-菲咯啉(phen)代替bpy,MMA的聚合反应速率加快,但其分子量分布稍宽(1.40左右),并进一步研究了bpy和phen作为混合配位剂时对MMA反向ATRP聚合的影响。用RATRP反应所得的带有卤素端基的PMMA作为苯乙烯ATRP的大分子引发剂,成功地合成了具有预期结构的苯乙烯与甲基丙烯酸甲酯嵌段共聚物,大分子引发剂的引发效率接近于1,说明在RATRP过程中由自由基引发剂引发MMA进行一般自由基聚合反应的可能性甚微。

Study on the reverse atom transfer radiucal polymerization of methyl methacrylate

The reverse atom transfer radical polymerization(RATRP) of methyl methacrylate (MMA), with acetonitrile as solvent and AIBN (AIBN/CuCl~2·2H~2O/1,10-phenanthroline or bpy=1:2:4 molar ratio) as initiator at 60℃ has been achieved successfully. It was found that the polydispersity of poly(methyl methacrylate)(PMMA) synthesized by using RATRP with bpy as ligand was as narrow as 1.08, but the inducing period of polymerization was quite long. while bpy was replaced with 1,10-phenanthroline(phen) as ligand, increases of both polymerization rate for MMA and polydispersity index (at round 1.40) for PMMA were observed. Thus, the mixture ligand of bpy and phen could be used to adjust the polymerization rate of MMA and the polydispersity of PMMA for such a RATRP system. The prepared PMMA containing end group of chlorine with narrow polydispersity could initiate the styrene (St) quantitatively to synthesize the well- defined block copolymer of MMA and St with CuX/bpy as catalyst at 120 ℃. Such a block copolymer was characterized by using GPC and ^1H NMR respectively. It was found that the possibility of general free radical polymerization of MMA in RATRP due to the decomposition of AIBN could be neglected.