Normal forces between cellulose surfaces measured with colloidal probe microscopy

Colloidal probe microscopy was employed to study interactions between cellu lose surfaces in aqueous solutions. Hydrodynamic forces must be accounted f or in data analysis. Long-range interactions betweeen cellulose surfaces ar e governed by double-layer forces and, once surfaces contact, by osmotic re pulsive forces and viscoelasticity. Increasing the ionic strength decreases surface potentials and increases adhesive forces. Polyelectrolytes cause s trong steric repulsion at high surface coverage, where interactions are sen sitive to probe velocity. Polymer bridging occurs at low coverage. The conf ormation of adsorbed polyelectrolytes depends on the polymer concentration. (C) 2000 Academic Press.