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 nanoparticles 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 nm. 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. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008