Detection of propagating radicals in the radical polymerization and estimation of their redox potentials.

自由基聚合是高分子化学中最成熟的领域之一，人们对乙烯基化合物的自由基聚合进行了大量的研究。然而，增长自由基的物理化学性质问题仍然没有得到解决。ESR光谱被认为是澄清这些问题的潜在方法之一。我们利用新型腔体：ESR成功地检测了乙烯基化合物自由基聚合中瞬态物种的ESR光谱。直接在室温下观察了未聚合成高聚物的乙酸异丙烯酯和乙烯基醚的增长自由基的光谱。因此，从增长自由基的结构出发，讨论了这些单体不能通过自由基引发剂获得高聚物的原因。此外，在ESR研究中发现了关于增长自由基物理化学性质的新信息。然而，由于随着氧化还原电位测量仪器的安装，ESR光谱仪的灵敏度降低，我们无法成功估算增长自由基的氧化还原电位。

The radical polmerization is one of the most established fields in polymer chemistry,and a lot of studies have been carried out on the radical polymerization of vinyl compounds.However,problems still remain unsolved on the physicochemical propeties of the propagating radicals.The ESR spectroscopy has been considered to be one of the potential method for the clarification of these problems.we succeeded on the detection of the ESR spectra of the transient species in the radical polymerization of vinyl compounds by using the new type of cavity:the ESR spectra of the propagating radicals of isopropenyl acetate and vinyl ethers,which did not polymerize to high polymer,were observed directly at room temperature.Accordingly, reason why high polymers could not be obtained from these monomers by radical initiators was discussed on the basis of the structure of the propagating radicals. In addition,new information on the physicochemical property of the propagating radicals was found in the ESR studies.However,we could not succeeded in the estimation of the redox potentials of the propagating radicals,because the sensitivity of the ESR spectrometer decreased with mounting the instrument for the measurements of the redox potentials.