ToF-SIMS studies of the adsorption of epoxy resin molecules on organosilane-treated aluminium: Adsorption kinetics and adsorption isotherms

Time of flight secondary ion mass spectrometry (ToF-SIMS) has been employed for the study of the adsorption of epoxy resin molecules, diglycidyl ether of bisphenol A (DGEBA), on aluminium substrates treated with an organosilane, γγ-glycidoxypropyltrimethoxysilane (GPS). Both the kinetics of adsorption and the thermodynamics have been examined, by the construction of adsorption isotherms. The kinetics of adsorption was investigated to establish an exposure equilibrium time for DGEBA adsorption onto GPS-treated aluminium. Specimens were treated with three different concentrations of DGEBA solution and six times of treatment. It was found that DGEBA molecules were adsorbed on the aluminium substrate and reached a true adsorption equilibrium after 10 min. Adsorption isotherms were then produced to define the type of adsorption. Two possible types of adsorption isotherms, Langmuir and Temkin, were examined, and DGEBA adsorption was found to be of the Langmuir type, providing a better fit than Temkin adsorption. Using a modified form of the Langmuir equation, the fractional monolayer coverage of DGEBA molecules was determined.