Some properties of siloxanyl methacrylate/N-vinyl pyrrolidone copolymers produced by gamma-irradiation

Crosslinked homopolymers of methacryloxymethylpentamethyldisiloxane (MMS) and N-vinyl-2-pyrrolidone (VP) have been produced by γ-irradiation of the monomers in the absence of a crosslinking agent. Similarly, crosslinked copolymeric xerogels were obtained from MMS/VP mixtures. High conversion was attained with the dose used, 2 Mrad (20 kGy) at a fixed dose rate of 0.01 Mrad/h (100 Gy/h). On decreasing the dose rate there was no evidence for proliferous polymerization or popcorn formation (noted previously for the n-butylacrylate/VP system). The homopolymers were optically clear, but the copolymers displayed translucency, haziness or opacity. Hydrogels and organogels were obtained by swelling the copolymers in water and toluene respectively. The influence of copolymer composition and concentration of added hexafunctional crosslinking agent on (i) the optical appearance of xerogels, hydrogels and organogels, (ii) the equilibrium solvent content of swollen gels, (iii) sol fractions have been noted and discussed. (author)