Surface segregation of components in semi- and full interpenetrating networks based on cross-linked polyurethane, poly(esteracrylate), poly(butyl methacrylate) and poly(vinyl acetate) has been studied at the interfaces with solids of high and low free surface energy. The method of attenuated total reflectance in IR spectra was used to estimate the composition of the system near the interface. It was found that the composition of the surface layers changes as compared with that of initial interpenetrating polymer networks (IPN) depending on the nature of the surface. It was also established that the surface segregation depends on the kinetic conditions of the reaction and on the method of curing. The latter effects are connected with microphase separation proceeding simultaneously with curing.