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REESTIMATION OF PROPAGATION RATE CONSTANTS IN THE RADICAL POLYMERIZATION

自由基聚合中传播速率常数的重新估计

基本信息

批准号：
11650916
负责人：
KAMACHI Mikiharu
金额：
$ 1.02万
依托单位：
FUKUI UNIVERSITY OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Electron spin resonance (ESR) spectroscopy is a very useful tool to investigate fundamental processes in radical polymerization systems, because information on structures, concentrations, and dynamics of paramagnetic species can be directly obtained from ESR measurements. However, ESR spectroscopy was considered to be difficult to acquire kinetic data owing to the experimental limitation. Fortunately, we found that well-resolved ESR spectra of the propagating radicals of vinyl and diene compounds could be observed by a conventional CW-ESR spectrometer. Accordingly, kp values for the polymerization of vinyl or diene compounds were estimated on the basis of experimental results obtained from ESR measurement, and compared the obtained k_p values and kinetic parameters with those estimated by PLP method.Propagation rate constants (k_p) for the free radical polymerization of n-butyl methacrylate (nBMA) in toluene solution were measured by ESR spectroscopy in the temperature range from-30 to 90 ℃. The Arrhenius parameters A and E_a were estimated to be (3.40±0.4) x 10^6 M^<-1> s^<-1> and (22.0±1.0) kJ/mol, respectively., which were in fair agreement the corresponding data obtained from the pulsed laser polymerization (PLP). Reestimation of kp values for vinyl monomers was performed by ESR spectroscopy. Moreover, Well-resolved electron spin resonance (ESR) spectra of propagating radicals in radical polymerizations of vinyl chloride have been detected for the first time under irradiation.The value of k_p for the radical polymerization of vinyl chloride was also estimated by ESR spectroscopy. Value of k_p for vinyl chloride was (5400±1500) M^<-1> s^<-1> at 25℃, which is in agreement with one of those obtained by the rotating sector method.

电子自旋共振（ESR）光谱是一个非常有用的工具，研究自由基聚合体系中的基本过程，因为顺磁物质的结构，浓度和动力学的信息可以直接从ESR测量获得。然而，ESR波谱被认为是难以获得动力学数据，由于实验的限制。幸运的是，我们发现，很好地解决了电子自旋共振光谱的乙烯基和二烯化合物的传播自由基可以观察到一个传统的CW-ESR光谱仪。因此，乙烯基或二烯化合物聚合的kp值是根据ESR测量得到的实验结果估算的，用ESR波谱法测定了甲基丙烯酸正丁酯（nBMA）在甲苯溶液中的自由基聚合反应的增长速率常数（kp），并与PLP法估算的kp值和动力学参数进行了比较。30至90 ℃。求得Arrhenius参数A和E_a分别为（3.40±0.4）× 10^6 M^<-1>s^<-1>和（22.0±1.0）kJ/mol。其与从脉冲激光聚合（PLP）获得的相应数据相当一致。乙烯基单体的kp值的重新估计通过ESR光谱进行。此外，还首次在辐照条件下观测到氯乙烯自由基聚合中增长自由基的高分辨电子自旋共振（ESR）谱，并估算了氯乙烯自由基聚合的k_p值。在25℃时，氯乙烯的kp值为（5400±1500）M·<-1>s·<-1>，与用旋转扇形法测得的结果一致。