A novel and simple method of preparation of poly(styrene-B-2-vinylpyridine) block copolymer of narrow molecular weight distribution: Living anionic polymerization followed by mechanism transfer to controlled/"living'' radical polymerization (ATRP)

A novel and simple method of preparation of a block copolymer of styrene and 2-vinylpyridine with narrow molecular weight distribution is reported. The novelty lies in the transformation of the polymerization mechanism from living anionic to controlled/"living" radical polymerization (ATRP). Thus, anionic polymerization of styrene is carried out in benzene using sec-butyllithium as the initiator followed by termination with ethylene oxide to prepare hydroxy-terminated polystyrene (PS-OH). PS-OH is converted to chloride-terminated polystyrene (PS-Cl) by a displacement reaction involving thionyl chloride and pyridine in benzene. PS-Cl is used to initiate the heterogeneous ATRP of 2-vinylpyridine in p-xylene with CuCl/2,2'-bipyridine system. The polymers synthesized are characterized by gel permeation chromatography (GPC), thin layer chromatography (TLC). IR and proton NMR spectroscopies.