| Abstract: | We have used a recently developed surface force balance to measure, with extreme sensitivity, both lateral and normal forces between interacting surfaces, for the case of simple liquids and particularly with surface-attached polymers. The presence of polymers on the surfaces reduces drastically the force required to maintain them in sliding motion, under a given normal load, relative to the bare surface case. We believe this is due to the long range steric repulsion which can sustain a large normal load while maintaining a very fluid interfacial layer. The effect is much more marked for end-tethered chains in a good solvent than for adsorbed chains in a θ-solvent. This is attributed to the different extents of interpenetration of the compressed polymer layers. |
