SURFACE ANALYTICAL STUDY OF THE INTERACTION BETWEEN GAMMA-AMINO PROPYL TRIETHOXYSILANE AND E-GLASS SURFACE .1. TIME-OF-FLIGHT SECONDARY ION MASS-SPECTROMETRY

Time-of-flight secondary ion mass spectrometry has been used to study the interaction of gamma-amino propyl triethoxysilane with an E-glass surface. The fragmentation pattern has been interpreted by assigning a series of mass peaks to the structural unit of the poly(aminosiloxane). The composition of the coating is complicated by the presence of polydimethylsiloxane and its copolymers. The highest mass fragment was obtained from the coating exposed by extraction with warm water (697 AMU). The largest molecular fragments would appear to have degrees of polymerization of 6 with differing numbers of silanol groups. On re-extraction with hot water the fragment size decreased. It is postulated that the network chain length of the three-dimensional polymer decreased as the interface was approached. At the glass surface a chemically bound molecular layer could be identified. The full chemical nature of the deposit is complicated by the incorporation of aluminium from the substrate into the coating. It was also possible to confirm that a layer of warm-water soluble oligomers existed at the air interface.