Ammonium salt catalyzed copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride

Ammonium salt catalyzed copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride was studied. The conversion curves could be linearized by the first order equation and the experimental rate constants k_exp for the initiation by various ammonium salts were determined. The rate of copolymerization was found to depend on the size of the cation but not on the type of anion. k_exp is a function of the first power initiator concentration but is independent of epoxide and anhydride concentration. The activation energy for the cetyltrimethylammonium bromide (CAB) initiated copolymerization in nitrobenzene was determined to be 73,5 kJ/mol. The kinetic scheme of copolymerization, which agrees well with the experimental results, was solved. The rate constant of the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride catalyzed by CAB in nitrobenzene was found to be 2,76·10^?2l.mol^?1·s^?1. The ratio of rate constants for both propagation steps, i.e. reaction of carboxylate anion with epoxide (k₃) and reaction of alkoxide anion with anhydride (k₂), was determined to be k₃/k₂ = 0,2 ± 0,1.