Castor oil-based acid urethane macromers were prepared and employed for obtaining Ag/Au/polymer nanocomposites. Structure and UV induced photopolymerization of the macromers were investigated by spectral methods. The polymerization rate and the degree of conversion decreased with about 10% in the presence of 2.5 wt.% silver nanoparticles (Ag NPs). For the diacid macromer, the surface plasmon intensity increased with irradiation time (the optical density of the absorption maximum (430 nm) attained 2.3 after 600 s), whereas a diminished efficiency was found for Ag NPs in situ generated. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed uniform distribution of the spherical nanoparticles (0.6 nm (Ag NPs): 5 nm (Au NPs)) and the appearance of Ag 3d(3/2), Ag 3d(5/2), Au 4f(7/2) and Au 4f(5/2) peaks corresponding to Ag (0) or Au (0). Environmental scanning electron microscope with energy-dispersive X-ray detector, contact angle and mechanical parameters measurements complemented the above observations. (c) 2012 Elsevier Ltd. All rights reserved.