COMPUTATION OF FORCES BETWEEN SPHERICAL COLLOIDAL PARTICLES - NONLINEAR POISSON-BOLTZMANN THEORY

A numerical scheme has been developed to calculate the electrical doub le-layer force between two spherical colloidal particles based on the nonlinear Poisson-Boltzmann theory. Results for identical spheres inte racting under constant surface potential, constant surface charge, or equilibrium dissociation of ionizable surface groups are given. The me thod can be readily applied to the case of nonidentical spheres. These results serve as benchmarks for delineating the accuracy of approxima te methods for the calculation of the interaction between particles ba sed on the Deryaguin approximation, the superposition approximation, a nd the Hogg-Healy-Fuerstenau approximation, as well as numerical solut ions of the problem based on the linearized Poisson-Boltzmann (Debye-H uckel) theory. (C) 1994 Academic Press, Inc.