Effect of thiourea on the radical polymerization of vinyl monomers. Part I. Polymerization of acrylonitrile with the hydrogen peroxide–thiourea catalyst system
Effect of thiourea on the radical polymerization of vinyl monomers. Part I. Polymerization of acrylonitrile with the hydrogen peroxide–thiourea catalyst system
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DOI：
10.1002/pol.1965.100030820
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发表时间：
1965-08
期刊：
影响因子：
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通讯作者：
T. Sugimura;Noboru Yasumoto;Y. Minoura
中科院分区：
文献类型：
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作者：
T. Sugimura;Noboru Yasumoto;Y. Minoura
以过氧化氢(H_2O_2)为催化剂，硫脲(TU)为助催化剂，在30℃的水溶液中研究了丙烯腈(AN)的聚合反应，由于聚合温度较低，AN不能单独用过氧化氢聚合。在反应体系中加入TU后，聚合反应立即发生，聚合速率随TU浓度的增加而增加。为了得到完整的聚合方程，对聚合速率与过氧化氢和硝酸铵浓度的关系进行了动力学研究。结果表明，总聚合速率Rp可用公式Rp表示：Rp=K[TU]Fr12；[H_2O_2]Fram 12；[An]，其中K为速率常数。TU存在时的加速作用可能是由于H_2O_2与TU之间的氧化还原反应迅速产生自由基所致。用不同的N-取代TU衍生物考察了取代基对反应的影响。随着吸电子取代基的加入，聚合速率与取代基的σ*常数呈线性增加。在此基础上对聚合反应机理进行了探讨。
The polymerization of acrylonitrile (AN) was studied in aqueous solution with hydrogen peroxide (H2O2) as catalyst and thiourea (TU) as cocatalyst at 30°C. Since the polymerization was carried out at a relatively low temperature, AN was not polymerized by hydrogen peroxide alone. Upon addition of TU to the reaction system, polymerization occurred immediately, and the rate of polymerization increased with increasing TU concentration. In order to obtain the overall polymerization equation, the dependence of polymerization rate on H2O2 and AN concentration was studied kinetically. It was found that the overall polymerization rate Rp was represented by the equation: Rp = K[TU]frac12;[H2O2]frac12;[AN], where K is the rate constant. The acceleration in the presence of TU might be attributed to a redox reaction between H2O2 and TU which would produce free radicals rapidly. The effect of substituents was investigated by use of various N-substituted derivatives of TU. The polymerization rate increased linearly with the σ* constants of the substituents as electron-withdrawing substituents were added. The polymerization mechanism is discussed on the basis of the results.