Polyethylene-g-Polystyrene Copolymers by Combination of ROMP, Mn2(CO)10-Assisted TEMPO Substitution and NMRP

The synthesis of polyethylene-graft-polystyrene copolymers by a multistep "grafting from" approach is described. In the first step, a bromo-functional polyethylene (PE-Br) was synthesized via ring opening metathesis polymerization (ROMP) of cis-cyclooctene (COE) and quantitative hydrobromination. Subsequent irradiation of PE-Br under visible light in the presence of dimanganese decacarbonyl (Mn-2(CO)(10)) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) resulted in the formation of TEMPO-substituted polyethylene (PE TEMPO). Polystyrene (PS) chains were then grown via nitroxide mediated radical polymerization (NMRP) from the PE-TEMPO precursor to give desired PE-g-PS copolymers in a controlled manner. The intermediates at each step and final graft copolymers were characterized by H-1 NMR, FT-IR, GPC, and DSC analyses.