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首页> 外文期刊>Applied Magnetic Resonance >Time-resolved Fourier-transform and continuous-wave ESR studies on photo-initiated polymerization
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Time-resolved Fourier-transform and continuous-wave ESR studies on photo-initiated polymerization

机译：光引发聚合反应的时间分辨傅里叶变换和连续波ESR研究

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Radical polymerization of vinyl monomers as initiated by the diphenylphosphinoyl (DPO) radical which is formed by the photo-cleavage of 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TMDPO) was investigated by continuous-wave electron spin resonance (cw ESR) and Fourier-transform (FT) ESR. Well-resolved hyperfine structures (hfs's) of the starting radicals were observed by the time-resolved cw ESR for vinyl acetate, ethyl vinyl ether, styrene, methyl methacrylate (MMA), and isoprene. The rates of formation and the spin-lattice relaxation were determined by time-resolved FT ESR for these starting radicals. In the polymerization of MMA and isoprene the primary propagating radicals were found for the first time by the observation of their well-resolved hfs's with time-resolved cw ESR. On the basis of the kinetic analysis including the spin-lattice relaxation, the rates of formation and the spin-lattice relaxation were determined by simulation of the time profile of FT ESR for the primary propagating radicals of MMA and isoprene. The rate of the primary propagating step was found to be by two orders greater than an average value of whole propagating steps as obtained by a steady-state measurement. [References: 22]
机译：通过连续波电子自旋共振（cw ESR）和傅里叶研究了由2,4,6-三甲基苯甲酰基二苯基膦氧化物（TMDPO）的光裂解形成的由二苯基膦酰基（DPO）自由基引发的乙烯基单体的自由基聚合。 -转换（FT）ESR。通过时间分辨的CW ESR对乙酸乙烯酯，乙基乙烯基醚，苯乙烯，甲基丙烯酸甲酯（MMA）和异戊二烯进行了观察，可以很好地分辨起始自由基的超精细结构（hfs）。通过时间分辨的FT ESR确定这些起始自由基的形成速率和自旋晶格弛豫速率。在MMA和异戊二烯的聚合反应中，通过观察它们的良好分解的HFS和时间分解的CW ESR，首次发现了主要的自由基。在包括自旋晶格弛豫在内的动力学分析的基础上，通过模拟FT ESR对MMA和异戊二烯的主要自由基的时间分布，确定了形成速率和自旋晶格弛豫。发现一次传播步骤的速率比通过稳态测量获得的整个传播步骤的平均值大两个数量级。 [参考：22]

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