Redox-Initiated Bulk Polymerization of Methyl Methacrylate Using a CuO/TiO2 Catalyst System

Abstract

Catalytic bulk polymerization of methyl methacrylate (MMA) has been carried out at 80°C over pure titania (anatase), and supported CuO/TiO2 catalyst system of different CuO % loadings (ranged between 0.5–20 wt%), without using an initiator or cocatalyst. The produced polymers were characterized via hydrogen nuclear magnetic resonance (1HNMR) and gel permeation chromatography (GPC). The prepared catalyst samples were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2-adsorption-desorption. The polymer yield (%) was shown to increase by increasing the CuO content up to 8.0 wt%, and then decreased. All polymers were of high molecular weights with low % of pentads. They were almost of syndiotactic-rich structure, produced mainly through a chain-end control mechanism. The polymerization process was suggested to be catalyst-dependent, redox-initiated and following a free radical mechanism. The sample of 8.0% CuO loading (above the monolayer coverage) was the most active; a fraction of loaded CuO existed on the titania external surface, while a larger fraction seemed to be inserted into the support pore system.