Preparation of poly(methyl methacrylate)/CaCO3/SiO2 composite particles via emulsion polymerization

A novel method to prepare organic/inorganic composite particles, i.e. poly(methyl methacrylate)/CaCO3/SiO2 three-component composite particles, using emulsion polymerization of methyl methacrylate with sodium lauryl sulfate as a surfactant in an aqueous medium was reported. CaCO3/SiO2 two-component inorganic composite particles were obtained firstly by the reaction between Na2CO3 and CaCl2 in porous silica (submicrometer size) aqueous sol and the specific surface area of the particles was measured by the Brunauer-Emmett-Teller (BET) method. The results show that the BET specific surface area of the CaCO3/SiO2 composite particle is much smaller than that of the silica particle, indicating that CaCO3 particles were adsorbed by porous silica and that two-component inorganic composite particles were formed. Before copolymerization with methyl methacrylate, the inorganic composite particles were coated with a modifying agent through covalent attachment. The chemical structures of the poly(methyl methacrylate)/CaCO3/SiO2 composite particles obtained were characterized by Fourier transform IR spectroscopy and thermogravimetric analysis. The results show that the surface of the modified inorganic particles is grafted by the methyl methacrylate molecules and that the grafting percentage is about 15.2%.