Copolymers of styrene (St), n-butyl acrylate (BA) and vinyltrimethoxysilane (VTMS) have been synthesized by emulsifier-free emulsion copolymerization using ammonium persulfate (APS) as initiator. Acrylic acid used as functional monomer was also added into the emulsion polymerization system. The effects of varying the concentrations of initiator and VTMS as well as the polymerization temperature on the polymerization conversion were investigated in detail. The copolymer was characterized by Fourier transform infrared spectrometer (FTIR). Copolymerization of VTMS with St and BA was confirmed by the appearance of an absorption peak between 1000 cm-1 to 1200 cm-1 (due to Si-O-C bonds) in the IR spectrum. The siloxane segments in the copolymer chain underwent hydrolysis and self-condensation, resulting in a change in the structure of the copolymers from linear into a cross-linked network. As a result, the organic and inorganic hybrid material was formed. The water absorption of emulsion decreased with increasing VTMS concentration. The polymerization conversion increased with increasing polymerization temperature, molar concentration of initiator and decreased with increasing molar concentration of VTMS.