Reaction Rate of the Formation of Graft Copolymer by the Coupling Reaction of Polystyryl Anion with Chloromethylated Polystyrene

Abstract

Chloromethylated polystyrene was reacted with polystyryl anion in tetrahydrofuran (THF) or in mixed solvents of THF—n-hexane at −78°C. The relative rate constants of the coupling reaction were measured photometrically by carrying out the competitive reactions of the polystyryl anion—chloromethylated polystyrene and the polystyryl anion—triphenylmethyl bromide. By using the analytical method of successive reactions, the relative rate constant of each step-wise process was estimated from the relative rate constant observed. It was found that the rate to form a 1-branched polymer decreased with increasing the degree of polymerization (DP) of polystyryl anion. Moreover, the tendency of the rate to decrease with the progress of the reaction became clearer when the DP of polystyryl anion and the volume fraction of n-hexane increased. The factors which influence the formation of the graft copolymer by a coupling reaction are considered in connection with these results.