Thin Solid Films, Vol.518, No.14, 3640-3645, 2010
Tracking the fate of gamma-aminopropyltriethoxysilane from the sol state to the dried film state
In this work, (29)Si nuclear magnetic resonance and Fourier-transformed infrared spectroscopy were combined to study the hydrolysis and polycondensation of gamma-aminopropyltriethoxysilane (gamma-APS), both in the liquid sol state and in the film state. gamma-APS sols were prepared in methanol or ethanol solvent in the pH range from 5.7 to 11 and deposited. The aim of the present study was to get the most complete picture in regard to the chemical events and time scale of these events. Transesterification reactions between gamma-APS and methanol result in faster kinetics in methanol compared to ethanol. gamma-APS films were deposited on aluminium and dried at ambient conditions (23 degrees C, 55% relative humidity). The silane films reached a chemical equilibrium in a couple of minutes (natural pH of 11) to 1 h (pH 7) depending on the pH of the silane solution. From a practical perspective, the results obtained here might give some clues to define an optimized schedule for the application of gamma-APS coupling agent to metals. (C) 2009 Elsevier B.V. All rights reserved.