Study On The Preparation And Properties Of SiO₂ Nanospheres/Polymethyl Acrylate Complex Emulsion

The progress in organic-inorganic nanocomposite provides new ideas and new ways for developing new functional materials. The properties of composite materials can be improved by adding the inorganic nanoparticles to the polymer. In this paper, the preparation and properties for spherical nano-SiO₂/polymethyl acrylate complex emulsion were studied. The potential application of the complex emulsion in the damping materials was also discussed.Firstly, the silica nanospheres were prepared by sol-gel method and were modified with the coupling agent, the core-shell structured nano-SiO₂/polymethyl acrylate complex emulsion with different content of silica were prepared by means of ultrasonic dispersion and seed emulsion polymerization. The effects of the content of nano-silica on the properties such as the mechanical stability of the complex emulsion, the hardness of the film, impact resistance, static and dynamic mechanical properties were studied. It was found that the mechanical stability of the complex emulsion was improved by the modification and coating of nano-silica, and the hardness, the impact resistance and the static mechanical performance of the complex latex film were greatly improved compared to the pure PMA by adding nano-inorganic particles. With increase of the content of silica, damping properties of the complex latex film decreased. But when the silica content increased continually, damping properties of the complex latex film would increase.Secondly, the monodispersed polystyrene （PS） microspheres used as the template at the presence of the SiOH groups on their surface were prepared by emulsifier polymerization, the silica shells were then coated on the PS microspheres by sol-gel method. Hollow silica nanoparticles with various diameters in the range of 50-70nm were obtained in a subsequent step by thermal degradation of the polymeric latex core. After surface treatment of the silica nanospheres, the core-shell structured nano- SiO₂/polymethyl acrylate complex emulsion was prepared by means of seed emulsion polymerization. It was found that the nano silica was dispersed stably and its compatibility with the polymer was promoted observably with modification. It also showed that compared to the pure PMA film, the mechanical properties of the complex film such as tensile properties, rigidity and damping capacity of the complex latex film were greatly improved.In addition, for comparison of the modification and coating of the nano silica, unmodified hollow nano-silica/polymethyl acrylate complex latex with different content of silica was prepared in situ copolymerization, and in the preparation, unmodified silica hollow nanospheres and industrial hollow silica spheres were used as raw materials blended with methyl acrylate. It was found that compared to the pure PMA film, the hardness, the static mechanical properties, impact resistance of the film were improved while the damping performance and the stability of complex emulsion were not good as core shell structured complex emulsion and film made from modified silica. To study the potential application of the complex emulsion in coating industry, the industrial hollow silica was used as filler in the preparation of latex paint used in the lab. The storage stability, viscosity, hardness and film-forming time of the latex coat were tested.