Interfacial dynamics of polydimethylsiloxane adsorbed on silica and titania nanoparticles of a wide range of specific surface area (S, 25-342 m(2)/g) and size (8-80 nm in diameter for primary particles) was studied employing differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). Both techniques revealed an increase of the interfacial polymer fraction with increasing of surface roughness S, accompanied with an enhancement of dynamics and cooperativity of the corresponding segmental relaxation (interfacial relaxation, alpha(int)). At the same time, bulk dynamics (glass transition temperature, T-g, and time scale of a relaxation) was not significantly affected. The results are discussed in terms of bimodal conformations of polymers adsorbed on solid surfaces and in terms of an increase of the apparent thickness of the interfacial layer with increasing of surface roughness. (C) 2015 Elsevier Ltd. All rights reserved.