This paper describes a new method to prepare graft copolymers, such as polyethylene-g-polystyrene (PE-g-PS), with a relatively well-controlled reaction mechanism. The chemistry involves a transformation process from the metallocene copolymerization of ethylene and m,p-methylstyrene (m,p-MS) to nitroxide-mediated ''living'' free radical polymerization (LRFP) of styrene. The metallocene catalysis produces ethylene-co-m,p-methylstyrene (EMS) random copolymers. Next, 1-hydroxyl-2,2,6,6-tetramethylpiperidine (HO-TEMPO) was synthesized by the reduction of TEMPO with sodium ascorbate. The macroinitiator (EMS-TEMPO) was synthesized with the bromination reaction of EMS, and the following nucleofilic reaction with this functional nitroxyl compound. The resulting macroinitiator (EMS-TEMPO) for LRFP was then heated in the presence of styrene to form graft copolymer. DSC, 1 H-NMR, FTIR spectroscopy were employed to investigate the structure of the polymers. The results of Molau test showed that PE-g-PS could be a potential good compatilizer.Bisindenyl ethane zirconium dichloride was synthesized by modification of the literature methods. 24 A brief description of this method is as follows. Scheme 1. Copolymerization reaction of ethylene with m,p-methylstyrene and following bromination reaction.Scheme 2. Synthesis of macroinitiator EMS-TEMPO and polyethylene graft copolymer.

A series of graft copolymers were synthesized based on ethylene‐co‐m,p‐methylstyrene (EMS) (backbone copolymer), ethylene‐1‐hexene‐m,p‐methylstyrene (EHMS) (backbone terpolymer), and polyethylene glycol monomethyl ethers (PEGM) (grafts) in this study. The PEGMs with molecular weights of 750 and 2000 were used. The chemical composition of the graft copolymers was analyzed by NMR and DSC measurements. The graft copolymers exhibited a phase‐separated morphology with the backbone and the methoxy polyethylene glycol (MPEG) grafts forming separate crystalline phases. The MPEG phase had a melting temperature lower than the corresponding MPEG homopolymer, as determined by DSC. The melting point of the crystalline phase formed by the EMS and EHMS main chains was lower than that of pure polymer backbone. Copyright © 2009 John Wiley & Sons, Ltd.