ELECTRICAL DOUBLE-LAYER INTERACTION BETWEEN DISSIMILAR SPHERICAL COLLOIDAL PARTICLES AND BETWEEN A SPHERE AND A PLATE - THE LINEARIZED POISSON-BOLTZMANN THEORY

The linearized Poisson-Boltzmann theory is used to calculate the elect rical double layer interaction free energy, as well as the double laye r force, between unequal spherical colloidal particles. Results are gi ven for interaction under conditions of constant surface potential, fo r constant surface charge, and for the case in which charge regulation due to the dissociation of surface groups may be modeled by a linear relationship between the surface charge and the surface potential. The interaction energy and force between a spherical colloidal particle a nd a plate, which has particular relevance to force measurements with the atomic force microscope and particle deposition studies, are also calculated. The results are used to test the accuracy of the linear De ryaguin approximation which forms the basis of the Hogg-Healy-Fuersten au formula. The validity of the linearized Poisson-Boltzmann theory is tested against a numerical solution of the nonlinear Poisson-Boltzman n equation in the special case bf spherical particles of the same size but opposite surface potentials.