Effective interaction of nonuniformly charged colloid spheres in a bulk electrolyte.

The interaction energy between two like-charged colloid spheres with nonuniformly distributed surface charges immersed in a bulk electrolyte is calculated under the linearized Poisson-Boltzmann equation. The calculated results are sensitive to the relative orientations of the spheres due to the anisotropy of the distribution of charges on the sphere surface. The effective repulsive interaction after thermal average is weaker than the case when charges are uniformly distributed on the spheres, and with the increase of the nonuniformity, an attractive interaction between the two spheres emerges.