Random copolymers of styrene, p-azidomethylstyrene and 1H,1H,2H,2H-perfluorodecyl methacrylate were prepared in two steps involving nitroxide-mediated radical copolymerization and azidation reaction and further characterized by H-1 and F-19 NMR, size exclusion chromatography, differential scanning calorimetry, and thermal gravimetric analysis. Ultrathin films of these azidomethyl-functionalized fluorinated random copolymers, with thicknesses ranging from 20 to 100 nm, were spin coated onto Si substrates and then crosslinked by ultraviolet irradiation resulting in smooth and insoluble crosslinked fluorinated polymer mats. The surface properties of the supported thin films were investigated by X-ray photoelectron spectroscopy and water contact angle measurements. These tailored photo-crosslinked coatings afford a versatile control and homogenization of the wetting properties of different organic and inorganic substrates. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3888-3895,2010