Reactivities of N‐alkylitaconimides in radical copolymerizations with styrene or methyl methacrylate

The radical copolymerizations of N ‐alkylitaconimide (RII, R = CH 3 , C 2 H 5 , n ‐C 3 H 7 , i ‐C 3 H 7 , n ‐C 4 H 9 , i ‐C 4 H 9 , CH 2 CH 2 Cl, CH 2 C 6 H 5 ) (M 1 ) with styrene (ST) (M 2 ) or methyl methacrylate (MMA)‐(M 2 ) were carried out at 60°C, using azobisisobutyronitrile as an initiator in tetrahydrofuran in order to clarify the substituent effect on the copolymerizations. The monomer reactivity ratios r 1 , r 2 and the Q 1 and e 1 values were determined from the results obtained. It was found that the relative reactivities 1/ r 2 of RII toward an attack by a poloystyryl radical could be correlated not by the steric‐substituent constant E s of the alkyl group in RII but by the polar‐substituent constant σ * in Taft's equation: log(1/ r 2 ) = ρ * σ * + δ E s . According to the above equation, the ρ * and δ values were obtained as 0.55 and 0, respectively, in the RII‐ST system, while in the RII‐MMA system, the ρ * and δ values were obtained as 0.49 and 0, respectively. It was also observed that the Q 1 values for RII were proportional to σ * constants and that the e 1 values for RII were independent of σ * substituent constant. It was also found that the weight‐average molecular weights of the copolymers are between 8.5 × 10 4 and 32.5 × 10 4 .