New bonding modes of gas-phase deposited (gamma)-aminopropyltriethoxysilane on silica studied by 29Si CP/MAS NMR

Besides the well-known reaction between the ethoxy groups of the silane end of the (gamma)-aminopropyltriethoxysilane (APTS) molecule and the silanols of silica, the amino ends of APTS molecules were observed to react in the gas phase with ethoxy groups of other APTS molecules and silanols of silica at elevated temperatures on the silica surface, dehydroxylated at 600 °C, forming Si–N linkages, as established by 29Si CP/MAS NMR.