Surface interactions and topological restrictions in liquids confined in nanopores. I. Light and neutron response in homologous systems

Abstract
We present Rayleigh wing, Raman, FT-IR and IQENS data on Ethylene Glycol (EG), EG monomethyl ether and EG dimethyl ether in bulk and confined in silica 26Å porous glasses, also with modified inner surface. From the data analysis it turns out : i) The IQENS and Rayleigh wing spectra for confined EG (two OH end groups) show a distribution of relaxation times described by a Havriliak-Negami profile. ii) EG monomethyl ether (one OH end group), when confined, exhibits a frustration in the molecular mobility linked to geometrical restriction and surface interactions. iii) For EG dimethyl ether (no OH end groups) the retardation processes are connected only to the physical traps, and, in the spectra, a Lorentzian profile is recovered. iv) The O-H stretching vibration analysis has been performed according to the current theories for associated liquids.