Investigation of surface properties of some polymers by a thermodynamic and mechanical approach: possibility of predicting mucoadhesion and biocompatibility.

Mucoadhesive properties of several polymers, such as sodium alginate, hydroxypropylmethyl cellulose, scleroglucan, xanthan gum, polyacrylic acid (Carbopol), and poly co-(methyl vinyl ether-maleic anhydride) (Gantrez), have been investigated by comparing a thermodynamical and a mechanical approach. Surface properties of polymers in the dry state have been studied by contact angle measurements and thermodynamical parameters derived by using different equations. This tensile adhesive strength of polymers in hydration conditions was measured by a modified DuNoy tensiometer. Comparison of the two different approaches has allowed us to conclude that thermodynamical consideration on surface energy can be used to evaluate mucoadhesive properties of materials. Data obtained with the two methods yielded a good linear correlation. Calculation of surface free energy of the considered materials also allowed a prediction of the water-polymer interface free energy: biocompatibility, defined according to the minimal interfacial free energy concept, could consequently be evaluated.