Investigation of resin–substrate interactions: An IETS study of phenol‐ and cresol‐ formaldehyde model compounds

The IET spectra of a number of phenol‐like, cresol‐like and methylolated ‘phenols’ are reported. These molecules are used as models of certain of the structural units found in a typical Novolac phenol–formaldehyde resin system. It is found that these poly‐phenolic molecules adsorb an aluminium oxide in predominantly the form of phenolate anions. In the case of those molecules in which the phenolate is associated with ortho‐methylol groups a site‐specific adsorption and a local near‐perpendicular alignment at the oxide surface is proposed. The spectra found also show that the formation of chemisorbed phenolate anion(s) occurs with adsorbate deprotonation and reaction with surface hydroxyl groups, with this latter process forming water which is then desorbed. The ease of this reaction suggests that the reverse process may be related to the loss of adhesion when a joint structure is exposed to water vapour.