Abstract

The authors perform a systematic study of the reaction of radical replacement of the dithiocarbonyl group of poly(methyl methacrylate) (PMMA) obtained by reversible addition–fragmentation chain transfer polymerization upon interaction with a radical azo initiator in an inert solvent at 80°C. It is shown that, for a polymer with a dithiobenzoate group, an increase in the molar ratio of the concentrations of the initiator and macromolecules with a terminal dithiobenzoate group to 100 equivalents promotes fast and quantitative replacement of the dithiobenzoate group by the initiator fragment and suppression of side chain termination reactions with the participation of radical intermediates. To replace the trithiocarbonate group, milder conditions are required, namely, a 20-fold molar excess of the initiator and a short reaction time of 2–5 h. The stability of the radical intermediates plays the decisive role in choosing the replacement reaction conditions. The reversible chain transfer agent formed during the replacement reactions, a low-molecular-weight compound containing a dithiocarbonyl fragment, can be repeatedly used for PMMA synthesis.

中文翻译：

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可逆加成-断裂链转移聚合获得的聚（甲基丙烯酸甲酯）二硫代羰基的自由基取代

抽象的

作者对在惰性溶剂中于80°C时与自由基偶氮引发剂相互作用的可逆加成-断裂链转移聚合反应获得的聚甲基丙烯酸甲酯（PMMA）的二硫代羰基进行自由基取代反应进行了系统的研究。结果表明，对于具有二硫代苯甲酸酯基团的聚合物，引发剂和具有末端二硫代苯甲酸酯基团的大分子的摩尔比与100当量的增加促进了由引发剂片段快速和定量地取代二硫代苯甲酸酯基团并抑制了自由基中间体参与的侧链终止反应 要取代三硫代碳酸酯基团，需要较温和的条件，即引发剂摩尔过量20倍，且反应时间较短，为2-5小时。自由基中间体的稳定性在选择替代反应条件中起决定性作用。在置换反应中形成的可逆链转移剂，一种含有二硫代羰基片段的低分子量化合物，可以重复用于PMMA合成。