Water at the interface modified silica filler-polydimethylsiloxane: quantum-chemical modelling

Intermolecular interactions determine the reinforcement of polydimethylsiloxane (PDMS) elastomers by fumed silica, and a water interlayer on the fumed silica/PDMS interface may act as a lubricant, decreasing the interaction energy and promoting the PDMS molecule motion over the tiller surface. A quantum-chemical (QCh) modelling has been performed to study a microscopic aspect of water impact on the intermolecular interactions in the system. The results obtained for a series of superclusters simulating fragments of the real silica filler surface, both hydroxylated and silylated, interacting with five-member PDMS oligomer in presence of individual water molecules and of a 'water drop'. of several H-bonded water molecules, are in good agreement with results from IGC adsorption experiments.