Copolymerization of acrylonitrile and vinyl pyridine

The copolymerization of acrylonitrile with 5‐ethyl‐2‐vinyl pyridine, 2‐vinyl pyridine, and 4‐vinyl pyridine has been investigated. The copolymer compositions have been determined by the titration of the copolymers in nonaqueous solvents with perchloric acid in glacial acetic acid, using methyl violet as an indicator. The reactivity ratios r1 and r2, respectively, have been determined in the three systems: AN/5‐ethyl‐2‐VP, (0.02 ± 0.02 and 0.43 ± 0.05); AN/2‐VP, (0.113 ± 0.002 and 0.47 ± 0.03); and AN/4‐VP, (0.113 ± 0.005 and 0.41 ± 0.09). The Q–e values for individual monomers have been calculated and compared with each other. The data obtained present no evidence for different reactivities of 2‐ and 4‐VP. The data shows that 5‐ethyl‐2‐VP has reactivity similar to those of above two monomers, but some difference caused by its ethyl group has been found. It has been also shown that the reactivity of 5‐ethyl‐2‐VP is quite identical with that of styrene.