Deuterated (amniopropyl) triethoxysilane (DAPES) and deuterated (aminobutyl) triethoxysilane (DABES) have been adsorbed on high surface area silica (Cab-O-Sil), dried, and probed with 2H (wide-line) and 29Si (CP/MAS) solic-state NMR techniques. When adsorbed, the DABES reacted to form siloxane linkages iwht he surface or other DABES molecules. The amount of DABES adsorbed on silica was dependent on the concentration of the silane coupling agent solution. The molecular motion of the adsorbed silane coupling agents on silica have been probed as a function of the amount and type of coupling agent. The slow-motional theory of Freed was used to simulate the resulting 2H spectra. The spectra were simulated by a superposition of a rigid and a mobile species.
