A Multidisciplinary Approach to the Use of Pyridinyl Dithioesters and Their <i>N</i>-Oxides as CTAs in the RAFT Polymerization of Styrene. Not the Chronicle of a Failure Foretold
作者:Angelo Alberti、Massimo Benaglia、Maurizio Guerra、Mihaela Gulea、Philippe Hapiot、Michele Laus、Dante Macciantelli、Serge Masson、Almar Postma、Katia Sparnacci
DOI:10.1021/ma050652d
日期:2005.9.1
of the dormant radical species intermediate in the RAFT process by the heteroaromatic rings as inferred from the measured reduction potentials of the compounds. Styrene polymerization was actually blocked at very low conversion in the case of the dithioisonicotinate N-oxide, and on the basis of ESR (electron spin resonance) studies it is suggested that in this case the dormant radical may actually act
测试了三种异构体吡啶基二硫代酯及其N-氧化物作为苯乙烯的RAFT(可逆加成断裂链转移)聚合反应的链转移剂的效率。邻位(二硫代吡啶甲酸根),间位(二硫代癸酸酯)和对位(二硫代异烟酸酯)异构体控制了苯乙烯的聚合,尽管相对于二硫代苯甲酸酯有一些延迟。延迟,对于N甚至更大从化合物测得的还原电势推断,这是由于杂芳环在RAFT过程中对休眠自由基物种中间体的过度稳定作用所致。在二硫代异烟酸的N-氧化物的情况下,苯乙烯的聚合实际上在非常低的转化率下被阻止,并且根据ESR(电子自旋共振)研究表明,在这种情况下,休眠基团实际上可以充当传播自由基的清除剂。激进的。尽管事先了解了给定CTA(链转移剂)的还原潜能,可以据此估计它在RAFT过程中形成的休眠自由基的稳定性,但原则上可以允许人们预测其性能,但这种预测必须慎重考虑。