Iqens study of the influence of confinement on diffusional dynamics of propylene glycol

The modification, compared to the bulk state, of the dynamics of liquids in confined geometry has attracted considerable interest in scientific research, also because of the close connection with many relevant technological problems, such as the building of optical switches, membrane separation, catalysis and tertiary oil recovery. We report the preliminary results of an Incoherent Quasi Elastic Neutron Scattering (IQENS) investigation on propylene glycol (PG: H[OCH(CH3)CH2]OH), a low molecular weight polymer, both in the bulk and in the confined state, in order to show the different dynamical behaviour of this system as a consequence of the presence of an interface. In particular PG was confined in 26 Å pores of a porous sol–gel glass with unmodified and modified inner surface, trying to distinguish the different role played by hydrophobic and hydrophilic confinement on its diffusive motion. The data have been interpreted in the framework of the well known Volino–Dianoux model for confined diffusion, and compared with the most recent literature in this field