The preparation of graft copolymers of polystyrene with poly‐2‐vinylpyridine

Abstract

AbstractGraft copolymers have been prepared with polystyrene backbones and poly‐2‐vinylpyridine side chains. The approach used was to couple together two preformed polymers which were themselves separately characterized. Thus, a knowledge of the overall composition and separate descriptions of the two homopolymers gave reasonably well defined grafts. The living‐polymer technique of Szwarc was found to be well suited to this approach. Polystyrene backbones were prepared by anionic polymerization, with Mw/Mn values of less than 1.1 and then chloromethylated to provide reactive grafting sites. The poly‐2‐vinylpyridine side chains were also prepared by anionic polymerization and, while still active, were allowed to react with the chloromethylated polystyrene. The homopolymers were removed by solvent extractions, leaving the graft copolymer as a residue. The molecular weight of the graft was then determined by osmotic‐pressure measurements. Several features of the synthesis and characterization of the grafts and of the homopolymers are discussed. Within very broad limits this method permitted an unrestricted choice of backbone and of side‐chain length and of the average number of side chains per backbone.