Alternating copolymerization of α-methylstyrene and maleic anhydride

Alternating copolymers of α‐methylstyrene (α‐MeSt) and maleic anhydride (MAn) were prepared by free‐radical‐initiated polymerization in bulk, benzene, or butanone as solvents. By applying the generalized model described by Shirota and co‐workers, the reactivity ratios k1c/k12 and k2c/k21 were calculated from the change of copolymerization rate with monomer feed at constant total monomer concentration. From the equation Rp = Rp(f) + Rp(CT) were calculated Rp(f) and Rp(CT), and it was found that in benzene the reaction proceeds predominantly by the addition of CT‐complex monomers, while in butanone, cross propagation of free monomers predominates. Termination occurs predominantly by homotermination of α‐MeSt macro free radicals, kt22, although the cross termination kt21 is also operative.