Photoelectron spectroscopic studies of the interfacial reaction between glass and commercial adhesive

The valence band and core‐level photoelectron spectroscopy [using X‐ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS)] were used to probe the interfacial reaction between glass and a commercial adhesive (Loctite). The interaction was investigated by comparing experimental valence band spectra with spectra calculated for various possible interaction schemes. The valence band spectrum for the interfacial region between the glass and the adhesive was obtained using difference spectra on a thin film of adhesive on glass. This film was sufficiently thin that the adhesion interphase could be directly probed. Chemical interaction occurs at the interface as evidenced by the fact that the spectrum for the interfacial region could not be represented by the addition of the spectrum of the glass alone and the adhesive alone. The XPS valence band spectrum and the UPS spectrum showed that the shallow top surface layer is very much enriched in acrylic acid, which is a minor component in the adhesive. When the Loctite adhesive was coated on glass, the C1s and O1s regions of the adhesion interface region showed evidences of new chemistry at the adhesive–glass interface. The possible reactions were evaluated by comparison of the experimental spectra with calculated ones based on different models using ab initio molecular orbital calculations. The experimental spectra are well represented by models where the acrylic acid of the surface region of the adhesive reacts with the glass, suggesting chemical interaction occurred at the adhesion interphase. Copyright © 2009 John Wiley & Sons, Ltd.