A fabric softner, N-beta-aminoethyl-gamma-aminopropyl polydimethyl-co-polydiphenylsiloxane (PASO), was synthesized by the polymerization of octamethyl cyclotetrasiloxane with an amino-functional silane and dimethyldiphenysilane. The chemical structure of the synthesized polysiloxane was characterized by Fourier transform infrared and H-1-NMR spectra. The morphology, composition, and hydrophobic properties of the PASO film were investigated by X-ray photoelectron spectroscopy, atomic force microscopy, contact angle measurement, and other measurements. The experimental results indicate that on the silicon wafer surface, PASO formed a hydrophobic, nonhomogeneous structural film. In addition, the atomic force microscopy results show that the PASO film deposited on the silicon wafer seemed to be slightly rougher than the film of the control, the N-beta-aminoethyl-gamma-aminopropyl polydimethylsiloxane. As a result, an orientation model of PASO is proposed on the basis of the characterization of the PASO film properties. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2715-2719, 2009