A new silicone containing macromonomer, 4-(methacrylamido) phenoxy polymethylhydrosiloxane (4-MPMHS) with a vinyl group, was successfully synthesized. Then poly (silicone-co-styrene-co-butylacrylate) with montmorillonite, P (Si-co-St-co-BA) with MMT nanocomposite emulsion was prepared by in situ intercalative emulsion polymerization of styrene (St), butyl acrylate (BA), and 4-MPMHS, in the presence of organic modified montmorillonite (OMMT) with different OMMT contents (0, 0.5, 1.0, 1.5, and 2 wt %). Potassium persulphate (KPS) was used as an initiator and sodium lauryl sulfoacetate (SLSA) and nonyl phenol ethylene oxide-40 U (NP-40) were used as anionic and nonionic emulsifiers, respectively. The resulting macromonomer was characterized by elemental analysis, Fourier transformer infrared (FT-IR), proton ((1)H NMR), and carbon ((13)C NMR) nuclear magnetic resonance spectroscopes. The OMMT was characterized by FT-IR and X-ray diffraction (XRD). The nanocomposite emulsions were characterized by using Fourier Transform infrared spectroscopy (FT-IR), laser light scattering, and surface tension method. Thermal properties of the copolymers were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and then the effects of OMMT percent on the water absorption ratio and drying speed were examined. Results showed that OMMT could improve the properties of emulsion. In other words, the properties of nanocomposite emulsions were better when compared with those of the silicone-acrylate emulsion. The property of nanocomposite emulsion containing 1 wt % OMMT was the best one, and the following advantages were obtained: smaller particle size, faster drying speed, smaller surface tension, and improved water resistance by the incorporation of OMMT. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1227-1237, 2012