Chemical bonding, adhesion acid base theory

The adhesion of paint films is influenced primarily by the chemical composition of the binder. Films may adhere by a mix of all possible mechanisms, for example. Dispersion forces, Acid-base interactions. Hydrogen bonding, covalent bond formation and other specific chemical interactions, such as chelation. In addition to these molecular interactions across an interface, the micro-roughness of the substrate can contribute by increasing the surface area and points of contact (see Mechanical theory of adhesion). In addition, if the substrate is itself another paint film (or a plastic), chain ends of the overcoating polymer can diffuse into the substrate, provided that the binder types are mutually compatible (see Theories of adhesion). 

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