Copolymerization of N-vinyl-2-pyrrolidone with 2,4,5-trichlorophenyl acrylate and with 2-hydroxyethyl methacrylate : Reactivity ratios and molecular weights

Abstract

The free radical copolymerization of N-vinyl-2-pyrrolidone ( 1) with 2,4,5-trichlorophenyl acrylate ( 2a) was carried out in chlorobenzene, and in the presence of AIBN, at 50°. Copolymerization of 1 with 2-hydroxyethyl methacrylate ( 2b) was also carried out similarly, except that methanol was employed as a solvent. In either case 7 copolymer samples were obtained by polymerization of mixtures of 1 and 2 (molar ratios 2:8 to 8:2) to about 10% conversion. Compositions of copolymer samples were estimated by micro-analysis (Cl and N), and in the case of copoly ( 1-2b) also by u.v. spectroscopy based on the carbonyl absorption of 1 at 207 nm. Reactivity ratios for 1 2a and 1 2b were computed by the Fineman-Ross method, and were found to be r 1 = 0.01 ± 0.02 and r 2a = 0.16 ± 0.01; and r 1 = 0.06 ± 0.10, r 2b = 4.35 ± 0.04, respectively. Estimation of the reactivity ratios by the Kelen-Tüdős method produced fairly similar values of r 1 = 0.02 ± 0.01, r 2a = 0.17 ± 0.01 and r 1 = 0.02 ± 0.14, r 2b = 4.50 ± 0.24. The molecular weight distributions of copolymers of both systems were examined by GPC. The trends noticed in the results are briefly discussed.