Preparation And Properties Of Nano-titanium Dioxide/Polyacrylate Composites

The TiO₂/Polyacrylate nanocomposites were widely applied in coatings, cosmetics, medicine and other fields. However, TiO₂ nanoparticles in polyacrylate matrix incline to aggregate together. To enhance the compatibility of the TiO₂ nanoparticles and the polyacrylate matrix is the key issue. The synthesis and silanized modification of TiO₂ nanoparticles as well as the incorporation of modified TiO₂ nanoparticles into the polyacrylate matrix were studied. The effective reinforcements of TiO₂ nanoparticles on the thermal, mechanical and UV-shielding properties of the polyacrylate matrix were investigated. Meanwhile, the application of TiO₂/Polyacrylate nanocomposites in coatings was discussed preliminarily.Pure anatase TiO₂ nanoparticles with 6 nm diameter were synthesized by a non-aqueous sol-gel process, on whose surface there is a lot of hydroxyl. Then the TiO₂ nanoparticles were modified with γ-Methacryloxypropyltrimethoxysilane（A174）, and the modified TiO₂ nanoparticles are positive charged. From the FT-IR spectrum and TGA curves, it could be inferred that A174 is successfully grafted onto the TiO₂ nanoparticles surface. The dispersity tests and contact angle tests indicate that the hydrophilic surface changes to lipophilic after modification.The TiO₂/ polymethyl methacrylate（PMMA） hybrid latex was synthesized by a miniemulsion polymerization process. The TiO₂ characteristic peak is appeared in the FT-IR spectrum and XRD patterns. The TEM pictures, SEM images and EDS analyses indicate that the TiO₂ nanoparticles are homogeneously dispersed in the PMMA matrix. TGA, DMA and tensile studies confirm that the thermal properties and mechanical properties of the resultant nanocomposites are significantly enhanced with respect to the neat PMMA. When increasing the TiO₂ nanoparticles loading from 0 to 3.0 wt%, the T0.5 of nanocomposites increases from 358.3 ℃ to 370.7 ℃, Tg increases from 93.1 ℃ to 108.3 ℃, storage modulus increases from 2243 MPa to 3289 MPa, tensile strength increases from 47.9 MPa to 62.8 MPa, Young modulus increases from 1.52±0.14 MPa to 2.83±0.12 MPa.The TiO₂/ poly（methyl methacrylate/butyl acrylate/methacrylic acid） [P（MMA/BA/MAA）] hybrid emulsion was prepared via a miniemulsion polymerization process. The TEM pictures of the latex particles show that the TiO₂ nanoparticles remain monodispersed in the polymer matrix. From the SEM micrographs and EDS spectra of the fracture surface of the nanocomposite films, it could be concluded that the TiO₂ nanoparticles are homogeneously dispersed in the nanocomposite films. The TGA and DSC results indicate that the T0.5 and Tg of the nanocomposites at 2.0 wt% TiO₂ nanoparticles loading is 11.5 °C and 9.2 ℃ higher than that of the neat polymer, respectively. From the UV-vis transmittance spectra, it can be seen that the neat polymer film only blocks part of the UV light below 280 nm, while the nanocomposite film blocks the UV light below 350 nm at most and still has a high visible transparency.