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

High mass resolution time-of-flight secondary ion mass spectroscopy (ToF-SI MS) has been employed to study the interaction between oxidized aluminium a nd hydrolysed gamma-glycidoxypropyltrimethoxysilane (GPS). The process used to prepare the specimens was similar to that used in the aerospace industr y. 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 o f nominal mass 71 and exact mass 70,9534, Its presence demonstrates the for mation of a covalent bond between aluminium and GPS, This result is also en hanced 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 co ntinuous mode to perform gentle etching of the surface. It is shown that th e Al-O-Si+ is the only fragment that is retained at mass 71, The other, org anic, features are quickly removed. This Is to be expected when profiling t hrough an interfacial layer where this type of specific interaction is pres ent. Crown Copyright (C) 2000. Reproduced with the permission of HMSO, Publ ished by John Whey & Sons, Ltd.