Synthesis of a linear polyethylene macromonomer and preparation of polystyrene-graft-polyethylene copolymers via grafting-through atom transfer radical polymerization

Abstract

A vinyl-terminated linear polyethylene (number-average molecular weight = 1800, weight-average molecular weight/number-average molecular weight = 1.7, functionality = 92%) prepared by ethylene coordination polymerization was transformed into a monohydroxy-terminated linear polyethylene by hydroalumination of the vinyl group with diisobutylaluminum hydride and subsequent oxidation and hydrolysis. This monohydroxy-terminated linear polyethylene was quantitatively converted into a linear polyethylene macromonomer with a terminal α-methacrylate group through esterification followed by dehydrobromination. A grafting-through atom transfer radical polymerization of the α-methacrylate-terminated polyethylene and styrene was performed to yield a well-defined polystyrene-graft-polyethylene copolymer. The number-average molecular weight of the graft copolymers, measured by gel permeation chromatography, was lower than the predetermined number-average molecular weight, presumably because of the intramolecular aggregation of polyethylene side chains. The α-methacrylate-terminated polyethylene content and number-average molecular weight of polystyrene-graft-polyethylene were determined by 1H-NMR. © 2007 Wiley Periodicals, Inc.