The influence of the different modifying agents on the synthesis of poly(methylmethacrylate)-calcium carbonate nanocomposites via soapless emulsion polymerization

The synthesis of poly(methylmethacrylate)calcium carbonate nanocomposites via the soapless emulsion polymerization was investigated after the CaCO3 nanoparticles were modified with different modifying agents. Such three kinds of modifying agents as sodium stearate (SS), oleic acid (OA), and PMMA were used to improve the surface property of CaCO3 nanoparticles. What was the most important factor to improve the amount of nano-particles in the composites is one of the general goals. As determined by Field-emission scanning electron microscopy (FESEM), the nanocomposites size of the diluted polymer emulsion was over 250 nm, while the sample without CaCO3 had a diameter of about 150 run. It was worth pointing out that the surface morphology of polymer changed from slick to scraggy, when the nano-CaCO3 particles participated in the polymerization process. The increase of the droplet size and the change of the polymer morphology indicated that the CaCO3 nanoparticles were present in the emulsion droplets. The X-ray diffraction results of the nanocomposites showed the existence of typical calcite peaks. The results of the TGA, FTIR, and the contact angles indicated that the hydrophobic surface of CaCO3 nanoparticles was crucial to improve the compatibility between the CaCO3 and MMA monomer in emulsion system. The results of the TGA, FTIR, and the contact angles indicated that the hydrophobic surface of CaCO3 nanoparticles was crucial to improve the compatibility between the CaCO3 and MMA monomer in emulsion system. (c) 2008 Wiley Periodicals, Inc.