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Polyimides have been extensively studied in view of their wide industrial applications. Adhesion to a substrate is essential for normal operation of devices. This problem is often solved by the use of an adhesion promoter on the surface of interest. A surface‐sensitive technique such as XPS has proved to be a powerful analytical tool for the analysis of the polymer/substrate interface. In the present paper, the interfaces of the SiO2/γ‐aminopropyltriethoxysilane (γ‐APS)/Pyralin system have been investigated at a precured stage. A detailed analysis of the molecular structures formed at the interface is carried out using XPS spectroscopy. An attribution of the various peak components is made with the help of accurate calculations of presumed core‐electron binding energies using a recent procedure based on the Density Functional Theory. Two acid–base mechanisms are described. The first one occurs between the ammonium end of the γ‐APS molecule and the silicon surface hydroxyl (NH3U+SiO‐), whereas the second one is formed between the ammonium end of the γ‐APS and the polymer carboxylic function (NH3U+COO‐). The results at the first interface are in contradiction with the expected stable oxygen‐bridged bond (siloxane), thus the rearrangement of the γ‐APS molecule upon heating, as suggested by Linde in a dynamic ‘Flip model,’ has been studied.

Following a rapid overview of the various mechanisms involved in the process of polymer adhesion to metals, modelling is attempted in order to describe, at molecular scale, the metal-polymer interface in its technological reality. In particular, the concept of an active site is explained and the role of these sites in bonding mechanisms is illustrated.The model is then verified in laboratory using experimental and theoretical techniques appropriate for the problem posed. Electrochemistry in organic environment is used to impart to the surfaces a homogeneous acid or basic character (i.e. electron acceptor or donor) and to set up an intense anisotropic electrical field allowing nonrandom simulation of the fields induced by the roughness of the potential of the surface of an industrial object. It is thus demonstrated that the establishment of a strong metal-polymer bond results from so-called Lewis acid-base reactions activated by the interfacial electrical field.Finally, the ageing study of the metal-polymer system thus obtained shows that the interface is stable relative to atmospheric oxygen and that vacuum pyrolysis converts the polymer into a carbon fibre strongly bonded to the metal.

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