Evaluation of adhesion forces in alginate-filler system using an AFM colloidal probe technique

Interaction and adhesion forces between polymer and mineral fillers are key factors in controlling their affinity during the preparation of high-quality nanobiocomposites. In this work, the compatibility between polymer (alginate) and mineral filler (mica, borax or bentonite) surfaces was characterized by direct force measurements using atomic force microscopy (AFM). Direct force measurements, using a single spherical alginate particle prepared by the spinning disc atomization method and attached to a cantilever, have been employed to characterize adhesion forces between alginate and several mineral filler surfaces in air. The free energies of adhesion for alginate-mica, alginate-bentonite and alginate-borax systems were compared. The experimental adhesion forces for these systems were compared with those predicted using the Johnson- Kendall-Roberts (JKR) approximation and the Liftshitz-van der Waals and Lewis acid-base interaction theory. The discrepancies between the experimental values and theoretical predictions were discussed on the basis of the surface roughness effect on the measured adhesion forces.