Synthesis of High Solid Content Polyacrylate/Nanosilica Latexes via Miniemulsion Polymerization

High solid content nanocomposites based on poly(methyl methacrylate-co-butylacrylate)/nanosilica was synthesized via miniemulsion polymerization in asemi-continuous operation. Oleic acid was used to act as a coupling agentbetween silica surfaces and polymer. Latexes with solid content of 42% were obtained,containing 5% by weight nano-SiO2 with respect to polymer. FTIR Results show themodified structure of silica with oleic acid and confirm the presence and bonding ofmodified silica on the polymer structure. Morphological investigations were performedusing TEM analysis. The results of microscopic images confirm the nanocompositestructure where the nanoparticles of silica are coated with the polymer nanolayers.Thermal analysis including DSC and TG/DTA was used to investigate Tg, thermalstability and thermal decomposition of the samples. The nanocomposite latex iscompared with the neat latex of the same monomer structure. The results of DTAanalysis show an increase of about 8°C in the degradation temperature. DSC Analysisshows that the glass transition temperature of the nanocomposite is higher than that ofpure acrylic latex. Moreover, the samples with improved hardness are compared withblank latex sample. All analyses demonstrate the well located silica nanoparticlesinside the latex polymeric structure.