Adhesive

Adhesive bonding may originate in a variety of ways. It may be the result of mechanical interlocking of the adhesive with the bonded surface, covalent bonding between bonded surfaces, or secondary electronic interactions between the bonded materials.

In mechanical adhesion, the adhesive flows around the substrate surface roughness so that interlocking of the two materials takes place. The adhesive may penetrate the substrate surface. Surface interpenetration often involves polymer diffusion; this type of bonding depends on the ability of the polymer adhesive to diffuse into the bonded surface.

Secondary electronic bonding may result from hydrogen bonds between the adhesive and substrate, from the interactions of overlapping polymer chains, or from such nonspecific forces as Van der Waals interactions.

In the case of covalent bonding, actual primary chemical bonds are formed between the bonded materials. For example, graft or block copolymers may bond different phases of a multicomponent polymeric material together.