DEVELOPMENT OF HIGH RESOLUTION ESR SPECTROSCOPY FOR DETAILED ANALYSIS OF RADICAL POLYMERIZATION

点击翻译按钮获取中文摘要

In order to increase the resolution and sensitivity of ESR spectroscopy, several kinds of trials were made based on improvements of an irradiation lens or a cavity.The most effective trial to increase the resolution and sensitivity of ESR spectroscopy was optimizations of preparation of samples and technique of measurements. Many kinds of conditions, for example, temperature, concentrations of monomers and initiators, irradiation time, wavelength, intensity, shape of sample tube, etc, will influence the resolution and sensitivity. Careful optimizations of these conditions were very important for the high resolution and sensitivity.New results were obtained by careful optimization of the measurement conditions in the improved spectrometer. Detailed analysis of ESR spectra of methacrylates showed clear chain length dependence. It was a first clear experimental evidence for detection of polymeric propagating radicals. Detection of intermediate radicals of reversible addition fragmentation chain transfer (RAFT) systems was also tried. Well-resolved ESR spectra of intermediate radicals were clearly observed. From these spectra, styryl end radical was clearly distinguished from end radical of maleic anhydride.