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以偶氮二异丁腈(AIBN)为引发剂,1,1-二苯基乙烯(DPE)为添加剂,对甲基丙烯酸甲酯(MMA)的自由基聚合过程进行了研究,并通过GPC、1H-NMR、ESI-MS表征了PMMA大分子的结构。结果表明,在DPE存在下,体系在一定程度上具备可控聚合的特征:聚合物分子量随单体转化率增加而增加,分子量分布较窄;DPE用量越大,相同时间下单体转化率越低;相同单体转化率下,DPE用量越大,聚合物的相对分子质量越低。PMMA大分子主要结构为一个DPE端基的链自由基和一个PMMA链自由基间偶合终止生成的含有一个DPE单元的特征结构。
The free radical polymerization of methyl methacrylate (MMA) was studied by using azobisisobutyronitrile (AIBN) as initiator and 1,1-diphenylethylene (DPE) as additive. The structures of PMMA macromolecules were characterized by 1H-NMR and ESI-MS. The results showed that the system possessed the characteristics of controlled polymerization to a certain extent in the presence of DPE. The molecular weight of the polymer increased with the increase of the monomer conversion and the molecular weight distribution was narrower. The larger the DPE dosage, the more the monomer conversion Low; the same monomer conversion, the greater the amount of DPE, the lower the relative molecular mass of the polymer. The main structure of the PMMA macromolecule is a structure containing one DPE unit generated by the termination of the coupling between a free radical of a DPE end group and a radical of PMMA chain.