The determination of adsorption isotherms by XPS and ToF-SIMS: their role in adhesion science

The study of the adsorption of characteristic ions or molecules from liquid solutions by XPS or ToF-SIMS is shown to be an important experimental meth od in adhesion science. The theoretical background to adsorption and experi mental procedures necessary to yield high-quality results are described. It is shown that in most cases adsorption data conforms to the Langmuir equat ion, which enables a parameter to be defined which is proportional to the i nteraction energy between absorbate and adsorbent. A series of examples of the approach are given involving the adsorption of macromolecules, organosi lane adhesion promoters, and other organic molecules on oxidised metal and carbon fibre substrates. The estimation of the surface acidity of carbon fi bres by measuring the capacity of the surface for derivatising ions is show n to improve the accuracy of the determination. (C) 1999 Elsevier Science L td. All rights reserved.