Surface analysis of emulsion adhesives by fast atom bombardment mass spectrometry and X-ray photoelectron spectroscopy

Abstract

This paper reports an investigation by fast atom bombardment mass spectrometry ( fabms) and X-ray photoelectron spectroscopy ( xps) of the nature of surfaces of films cast from various emulsion adhesives against air and against polystyrene or polytetrafluoroethylene ( ptfe) surfaces. An objective was to ascertain the extent to which the nature of the surfaces of films derived from emulsion adhesives depends upon the nature of the substrate against which the film is cast. The emulsion adhesives contained copolymers of vinyl acetate with vinyl neodecanoate ( vaw), with ethylene ( vae1, vae2, vae3) and with n-butyl acrylate ( vaba). FABMS spectra show that the compositions of the air-dried surfaces of the films from the vavv, vae1, and vae2 emulsions are essentially those of the respective copolymers, that the surfaces of films from the vaba adhesives comprise mainly copolymer, but there is some dodecylbenzenesulphonate surfactant also present, and that the composition of the surface of films from the vae3 emulsion is dominated by potassium ions. The fabms spectra indicate no differences between the surfaces of vae3 adhesive films cast against polystyrene and ptfe on the one hand, and the surface of vae3 adhesive dried in air on the other. The fabms spectra clearly demonstrate that interfacial failure occurs between vae3 adhesive films and polystyrene and ptfe substrates when the films are separated from the substrates. XPS spectra show that the air- and polymer-cast surfaces of films from vae3 and vaba emulsions are very similar, and that the surfaces of films from the vae3 emulsions contain 5–6% of potassium together with significant levels of carboxylate moieties.