Friction of gels. 3. Friction on solid surfaces

Frictions of several kinds of hydrogels, poly(vinyl alcohol) gel, gellan ge l, poly(2-acrylamido-2-methylpropanesulfonic acid) gel, and its sodium salt gel, sliding on glass plates as well as on Teflon plates have been investi gated both in air and in water. The frictional force and its dependencies o n the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement co ndition. The gel friction is explained in terms of interface interaction, e ither attractive or repulsive, between the polymer chain and the solid surf ace. Surface adhesion between glass particles and gels measured by atomic f orce microscopy showed a good correlation with the friction, which supports the polymer repulsion-adsorption model proposed by authors.