Preparation of Poly(methyl acrylate)/TiO2 Composites by Potassium Diperiodatocuprateinitiated Grafting Copolymerization

The effective chemical binding of polymeric chain with inorganic materials has acrucial impact on improving the integrative property of the composite. In thisstudy, potassium diperiodatocuprate (Cu3+) was used as an initiator to preparepoly(methyl acrylate)/TiO2 composites (PMA/TiO2) by in situ graft copolymerization inan alkaline medium. TiO2 particles were at first modified by aminopropyltriethoxysilane(KH550) before polymerization process in order to obtain the covalent bonds of PMAchain with TiO2 particles. The three synthetic parameters including the monomerconversion, grafting percentage and grafting efficiency were systematically evaluatedas functions of temperature, initiator concentration, pH and reaction time. The graftparameters were increased first and then decreased with increases in temperature,Cu3+ concentration and pH value of polymerization. It was also found from the experimental results that Cu3+ was a highly efficient grafting initiator for the copolymerization.The grafting efficiency was as high as 95% and the graft percentage was readilycontrolled within 460%. In addition, the highest graft parameters were observed at pH13.08 when the temperature was controlled at 30-40ºC. The structure of PMA/TiO2composite was characterized using the thermal gravimetric analysis (TGA), X-raydiffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The IRmeasurements clearly suggested that the PMA chains were effectively grafted ontoTiO2 surface. A single-electron-transfer mechanism was proposed to illustrate thegeneration of radicals by the redox reaction and the formation of PMA/TiO2 composite.