Binding metals to polymers. A short review of basic physical mechanisms

Normally metals do not bond to polymers. Binding metals to polymers is a complex phenomena which brings into play interfering modifications at different places : at the adhesive interface and within a thicker interphase layer. Bond formation at the interface is obtained by functionalisation of the polymer surface to make acid-base reactions with the metallic oxide (mainly hydrogen bonding with alumina). However, common practice shows that the main resistance to delamination stems from dissipation processes in the interphase region, the importance of which is tremendous for a strong adherence. Dissipation is conveniently modelled by the fracture mechanics parameter G, the energy release rate, and the way it can be built up from recent basic physical mechanisms is reviewed, either as a plastic dissipation (suction of polymer chains at crack tip) or as viscoelastic losses (far from the tip). From these models, some experimental features begin to be understood. (orig.)