ESR studies of molecular motion of spin labelled poly(methyl methacrylate)

Abstract

ERS studies of the nitroxide spin-labelled poly(methyl methacrylate) (PMMA) in the solid phase were carried out to obtain information about molecular motion of the order of nanosecond. The amorphous line-shape was partially averaged in the temperature range between 90 and 140°C, above which the spectra appeared isotropically and narrowed gradually. Three different methods were used to obtain the correlation times from the observed spectra over the wide range of temperature. The comparison of the correlation times determined by different analysis from identical data was discussed. The correlation times and the activation energies, which were obtained by different analyses from the identical data, were found to be nearly equal one to another. Although the mechanism of the fast mode of the motion of PMMA molecules in the solid phase is not yet well understood, it is plausible to assume that the motion resulting in the partial averaging is related to the rotation of the ester side chain. © 1977 The Society of Polymer Science, Japan.