Hydrozirconated styrene copolymer as a macroinitiator to in situ synthesize polyethylene/polystyrene-g-polyethylene alloy via coordination polymerization

Abstract

A new method to in situ synthesize polyethylene/polystyrene-g-polyethylene (PE/PS-g-PE) alloy based on hydrozirconation reaction with Cp2ZrHCl and coordination polymerization was reported. Hydrozirconation of vinyl-containing polystyrene (copolymer of styrene and 4-(vinylphenyl)-1-butene (PSVS)) was found to be an efficient way for immobilization of zirconocene pre-initiator onto polymer backbone by carbon-zirconium (C-Zr) sigma (σ) bond. By activation with MAO, the resultant hydrozirconated PSVS could act as a macroinitiator with multiple-initiating sites (Zrδ+-Cδ-) for ethylene insertion and propagation in “graft from” fashion. The hydrozirconation and the following ethylene polymerization were monitored by NMR and GPC, revealing the successful synthesis of PS-g-PE and the following formation of free PE chains due to chain transfer characteristic of metallocene catalyst. Thus we could prepare PE/PS-g-PE alloy through in situ ethylene polymerization by this method. The presence of PS-g-PE in the resultant alloy endowed some special functionalization, for example, acting as compatibilizer in PE/PS blends.