In situ radical polymerization of methyl methacrylate in a solution of surface modified TiO2 and nanoparticles
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Surface modified TiO2 nanoparticles dissolved in toluene were encapsulated in PMMA by in situ radical polymerization of methyl methacrylate initiated by 2,2-azobisisobutyronitrile. The surface modification of the TiO2 nanoparticles (average diameter of 4.5 nm) was achieved by the formation of a charge transfer complex between TiO2 nanoparticles and 6-palmitate ascorbic acid. The surface modified TiO2/nanoparticles were characterized using UV-Vis and FTIR spectroscopy, while the obtained polymer nanocomposites were characterized using reflection and H-1 NMR spectroscopy, as well as gel permeation chromatography. The influence of the TiO2 nanoparticles on the thermal properties of the PMMA matrix was investigated using thermo-gravimetric analysis and differential scanning calorimetry. The glass transition temperature of the polymer was not influenced by the presence of the nanoparticles while the thermal stability was significantly improved. (C) 2007 Elsevier Ltd. All rights reserved.