METHYLENE-BLUE AS A RETARDER OF FREE-RADICAL POLYMERIZATION .1. POLYMERIZATION OF ACRYLONITRILE, METHYL-METHACRYLATE AND STYRENE
METHYLENE-BLUE AS A RETARDER OF FREE-RADICAL POLYMERIZATION .1. POLYMERIZATION OF ACRYLONITRILE, METHYL-METHACRYLATE AND STYRENE
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DOI：
10.1016/0032-3861(82)90188-4
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发表时间：
1982-01-01
期刊：
影响因子：
4.6
通讯作者：
MANDAL, BM
中科院分区：
文献类型：
--
作者：
DAS, NK;MANDAL, BM
氧化还原染料亚甲基蓝（MB）在n -二甲基甲酰胺溶剂中以单体形式显著抑制苯乙烯（ST）和丙烯腈（AN） inN的自由基聚合。在甲基丙烯酸甲酯（MMA）聚合中影响较小。发现部分还原的MB是比MB更强的缓速剂。MB在60℃下氧化聚合物自由基的速率常数为ST>AN>MMA。如果只考虑自由基和底物的反应性和极性参数，就不能像Q-e格式那样解释结果。与PMMA自由基的低速率常数归因于空间效应。目前的研究表明，MB的单分子是有效的链终止者，这与Chen的结论形成了鲜明的对比，Chen认为在丙烯酰胺在水中聚合时，只有MB的聚集体是链终止者。
Methylene blue (MB), a redox dye, in monomeric form significantly retards the free radical polymerization of styrene (ST) and acrylonitrile (AN) inN,N-dimethyl formamide solvent. The effect is small in methyl methacrylate (MMA) polymerization. Partly reduced MB is found to be a stronger retarder than MB. The rate constants for the oxidation of the polymer radicals by MB at 60°C follows the order ST>AN>MMA. The results cannot be explained when only taking into consideration the reactivity and polarity parameters of the radicals and the substrate, as is done in the Q-e scheme. The low rate constant with the PMMA radical is attributed to steric effects. The current work has shown that single molecules of MB are effective chain terminators and this is in sharp contrast with the conclusion reached by Chen who postulated that only the aggregates of MB are the chain terminators in the polymerization of acrylamide in water.