Organosilicon-modified polyurethane have been synthesized using the prepolymer method and characterized by Fourier infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), solvent resistance analysis, and stressstrain tests. The FTIR spectra show that the polyurethane is fully reacted and polydimethylsiloxane (PDMS) is chemically incorporated into the copolymer. SEM reveals a multiphase structure with surface cracking and thermal analysis indicates that the heat resistance properties are better when the PDMS concentration is low. According to the solvent resistance, water and acetone uptake decreases when the PDMS content is less than 4 wt % while the ethanol uptake changes indistinctively. The mechanical properties of the films are also discussed. A tensile strength up to 6 wt % has the largest effect while the elongation at break decreases. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125:14861492, 2012