γ-Irradiation of N-vinylpyrrolidin-2-one and its homopolymer

Abstract

The effect of γ-radiation on N-vinylpyrrolidin-2-one and its homopolymer, poly(N-vinylpyrrolidin-2-one), has been investigated. With N-vinylpyrrolidin-2-one, polymerization occurs by a radical mechanism and the presence of water has been shown to have a promoting effect on the reaction, giving both increased polymerization rates and molecular weights. This has been primarily attributed to an enhancement of N- vinylpyrrolidin-2-one reactivity through hydrogen bonding. In contrast, irradiation of N-vinylpyrrolidin-2-one in the presence of organic solvents leads to lower polymerization rates and lower molecular weights than with the undiluted monomer. ��� Poly(N-vinylpyrrolidin-2-one) primarily crosslinks on being irradiated. Gel fractions have been determined as a function of radiation dose and the results shown to be consistent with the theoretical data derived by Inokuti for a polymer with an initial molecular weight distribution of the Schulz-Zimm type. This leads to values for the radiation chemical yields of crosslinks and main chain scissions, G(X) and G(S), of 0.13�0.03 and 0.02�0.01, respectively, at 0°C.