INS study of intermolecular interaction at the silicone-fumed silica interface

Surface vibrations of a varied-surface-silylation-degree of silylated fumed silica fine particles as well as the vibrations of a five-member polydimethylsiloxane oligomer Si5 adsorbed at different coverage on hydroxylated and silylated fumed silica have been studied by INS at low temperature and by DRIFT at ambient one. The changes in the AWDS spectra are recorded which might be attributed to sterical restrains caused by the densification of the trimethylsiloxy units packing on the surface of the silylated particles at the silylation degree exceeding 2.6, to immobilization of the adsorbed molecules on the surface, as well as to the pressure effect on the TMS units of substrate caused by adsorbed molecules. Assignment of the observed spectra is done on the basis of the solution of the direct and inverse spectral problems with the force field initially determined quantum-chemically.