Adhesion of polymer coils to a solid surface: influence of the depletion effect

The specific properties of polymer coils are often disregarded in theories of adhesion, but polymer properties are essential for the strength of the a dhesive bond. Polymer coils are repelled entropically from impenetrable sur faces. This causes the depletion effect and creates a layer of reduced conc entration right at the interface. To bond a polymer coil to a substrate, it must be forced actively towards the interface, driven by the gaining of ad sorption energy. The adsorption of specific groups in the (co)polymer, whic h interact with 'polar' sites on the substrate, must be used to suppress th e depletion. Adsorption diminishes the effective distance between the surfa ce and the adhesive polymer. The balance between adsorption and depletion ( rather than the effect of polar groups or pretreatments on the work of adhe sion as such) is the most important chemical possibility of affecting adhes ion. The strength of the bond between polymeric materials and solid surface s varies as H-3 with the effective distance H between the polymer and subst rate. Therefore, it changes by an order of magnitude when the polymer adhes ive is pulled towards the substrate by adsorption.