ORIENTATIONAL DIFFUSION OF THE TOLUENE-D(3) METHYL-GROUP IN SOLUTIONS AND POLYMER MATRICES

IR spectra of solutions of selectively deuterated toluene C6H5CD3 in the region of the asymmetric stretching vibrations of the CD3 group are studied. Pentane, non-deuterated toluene, dibutyl phthalate, acetone and polymers: polybutadiene (PBD), polypropylene (PP) and polymethyl methacrylate (PMMA) are used as solvents. In order to determine activation enthalpy DELTAH* and entropy DELTAS* of the orientational diffusion of the CD3 group the temperature dependencies of the absorption band widths delta of the asymmetric vibrations of this group are studied. An original method of estimating the errors in determining the values DELTAH* and DELTAS* within Rakov's approach is propsed and checked. The values obtained for DELTAH* do not exceed 1 kcal mol-1. No correlation of DELTAH* with either the dielectric permittivity or the viscosity of the medium was observed. The glass transition in dibutyl phthalate and PBD, as well as relaxation transitions in PP and PMMA, do not affect the dependence delta = f(T).