Evidence of specific interaction between ?-glycidoxypropyltrimethoxysilane and oxidized aluminium using high-mass resolution ToF-SIMS

Abstract

High mass resolution time-of-flight secondary ion mass spectroscopy (ToF-SIMS) has been employed to study the interaction between oxidized aluminium and hydrolysed γ-glycidoxypropyltrimethoxysilane (GPS). The process used to prepare the specimens was similar to that used in the aerospace industry. Fragments present at nominal mass m/z = 71 were examined carefully. The high mass resolution allowed us to show the presence of AlOSi+ fragment of nominal mass 71 and exact mass 70.9534. Its presence demonstrates the formation of a covalent bond between aluminium and GPS. This result is also enhanced by the detection of another feature in the mass spectra assigned to a fragment of structure AlOSi+ = CH2 detected at a nominal mass of m/z = 85. Depth profiles of these ions were obtained using the primary ion beam in continuous mode to perform gentle etching of the surface. It is shown that the AlOSi+ is the only fragment that is retained at mass 71. The other, organic, features are quickly removed. This is to be expected when profiling through an interfacial layer where this type of specific interaction is present. Copyright © 2000 John Wiley & Sons, Ltd.