Preparation of styrene-acrylic emulsion by using nano-SiO₂ as seeds

A styrene-acrylic/SiO₂ nanoparticle composite emulsion was prepared by using SiO₂ nanoparticles as seeds. The effect of factors such as the level of nano-SiO₂, reaction temperature and ultrasound treatment of nano-SiO₂ on the stability of the polymerization reaction was investigated. Water-resistance of the emulsion was measured. The level of nano-SiO₂ in the emulsion was determined by inductively coupled plasma (ICP) spectrometry. The particle morphology of the emulsion with nano-SiO₂ was observed with transmission electron microscopy (TEM). The kinetics of the polymerization was also studied at various temperatures and various levels of nano-SiO₂. They showed that the level of nano-SiO₂ and reaction temperature had a great influence on the monomer conversion, particle size, coagulum content and viscosity of the emulsion. Nano-SiO₂ treated by ultrasonics can increase the coagulum content greatly, but it does not improve the water resistance of the emulsion. The level of nano-SiO₂ in the emulsion was lower than the theoretical value. The reaction kinetics indicated that the level of nano-SiO₂ had less influence on the reaction rate than the reaction temperature. Even a small amount of nano-SiO₂ can decrease the reaction rate.