A Multidisciplinary Approach to the Use of Pyridinyl Dithioesters and Their N-Oxides as CTAs in the RAFT Polymerization of Styrene. Not the Chronicle of a Failure Foretold
A Multidisciplinary Approach to the Use of Pyridinyl Dithioesters and Their N-Oxides as CTAs in the RAFT Polymerization of Styrene. Not the Chronicle of a Failure Foretold
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在苯乙烯 RAFT 聚合中使用吡啶基二硫酯及其 N-氧化物作为 CTA 的多学科方法。
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发表时间：
2005
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影响因子：
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通讯作者：
K. Sparnacci
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作者：
A. Alberti;M. Benaglia;M. Guerra;M. Gulea;P. Hapiot;M. Laus;D. Macciantelli;S. Masson*;A. Postma;K. Sparnacci
考察了三种异构体吡啶基二硫酯及其n -氧化物作为链转移剂在苯乙烯RAFT（可逆加成裂解链转移）聚合中的效率。邻位异构体（二硫代苯甲酸酯）、间位异构体（二硫代苯甲酸酯）和对位异构体（二硫代苯甲酸酯）控制苯乙烯的聚合，尽管对二硫代苯甲酸酯有一定的阻碍作用。对n -氧化物的阻滞作用更大，这是由于杂芳烃环对RAFT过程中中间的休眠自由基的过度稳定，这是由化合物的测量还原电位推断出来的。在二硫代异烟酸n -氧化物的情况下，苯乙烯聚合实际上在非常低的转化率下被阻止，并且根据电子自旋共振（ESR）研究表明，在这种情况下，休眠自由基实际上可能作为传播自由基的清除剂。尽管事先知道给定CT的复位电位…
The efficiency of three isomeric pyridinyl dithioesters and their N-oxides as chain transfer agents in the RAFT (reversible addition fragmentation chain transfer) polymerization of styrene was tested. Ortho (dithiopicolinates), meta (ditionicotinates), and para (dithioisonicotinates) isomers controlled the polymerization of styrene although with some retardation with respect to dithiobenzoates. The retardation, which was even greater for the N-oxides, was attributed to excessive stabilization 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 as a scavenger of the propagating radical. Although the knowledge beforehand of the reduction potential of a given CT...