Infrared study of the silica/silane reaction. Part II

The grafting of different silanes and probe molecules on ULTRASIL® 7000 GR was studied with a special IR technique. A relationship between the molecular size of silanes and reacted silanols at the silica surface was determined. The accessibility of the SiOH-groups to the silane is decreasing with the increasing size of its alkyl group (stearic hindrance). VP Si 363® behaves different due to the additional adsorption possibilities of the long alkylpolyethergroups. The combination of ULTRASIL® 7000 GR with VP Si 363® shows the highest efficiency in silica/ silane coupling.