ISOTOPIC EFFECTS IN H-ATOM ABSTRACTION FROM MATRIX MOLECULES BY METHYL RADICALS IN POLY(METHYL METHACRYLATE) - DETERMINATION OF THE SCALE OF RELATIVE REAGENT MOTIONS

The H-abstraction by CH//3 and CD//3 radicals from PMMA molecules is investigated at 77 and 120 K. The film samples are prepared from the mixture of normal and deuterated PMMA. The reaction is of the first order with respect to radical concentration. Its rate is retarded in time as compared to the exponential law. An analysis of the molecular product ratio for the reaction allows the primary isotopic effects to be estimated. The initial reaction rate depends nonmonotonously on the proportion of the deuterated polymer in the matrix.