Polyethylene-g-poly(cyclohexene oxide) by Mechanistic Transformation from ROMP to Visible Light-Induced Free Radical Promoted Cationic Polymerization

A novel polymerization mechanism transformation strategy, combining ring-opening metathesis polymerization (ROMP) and visible light induced cationic polymerization, is successfully applied for the synthesis of polyethylene-graft-poly(cyclohexene oxide) (PE-g-PCHO). First, cis-cyclooctene (COE) was polymerized via ROMP in the presence of a chain transfer agent and quantitatively hydrobrominated to give bromo functional polyethylene (PE-Br). Subsequent irradiation of PE-Br in the visible range using dimanganese decacarbonyl (Mn2(CO)10) and diphenyl iodonium hexafluorophosphate (Ph2I+PF6–) as radical generator and oxidant, respectively, initiated cationic polymerization of cyclohexene oxide (CHO) resulting in the formation of PE-g-PCHO. The effect of irradiation time and Mn2(CO)10 concentration on the grafting density and efficiency was evaluated. Both the precursor polymers and the corresponding graft copolymers were characterized by 1H NMR and Fourier transform infrared (FT-IR) spectroscopy, gel-permeation chromatography (GPC), and differential scanning calorimetric (DSC) analyses.