Acid-base effects in polymer adhesion at metal surfaces

The Lewis acid-Lewis base properties of various polymers have been determined by measuring the contributions gamma(S)(+) and gamma(S)(-) to the solid surface free energy using the contact angle approach of van Oss, Chaudhury, and Good. A new linear method to solve for gamma(S)(+) and gamma(S)(-) is employed in addition to the usual approach which uses three simultaneous equations. The set of liquid surface tension parameters developed by van Oss, Chaudbury, and Good, and the recent set of values developed by Della Volpe and Siboni are both useful in distinguishing between acidic and basic polymers. The adhesion (peel force) of an acidic pressure-sensitive adhesive is greatest on a basic oxide film. In addition, the adhesion (pull-off force) of the basic polymer poly(methyl methacrylate) is greatest for acidic oxide films. Thus, direct experimental evidence is provided as to the importance of Lewis acid-Lewis base effects in the adhesion of polymers on oxide-covered metals.