Effective electrostatic interactions in suspensions of polyelectrolyte brush-coated colloids

Effective electrostatic interactions between colloidal particles were studied via linear-response theory. Analytical expressions were derived for the effective pair interaction and a one-body volume energy by applying the second-order perturbation theory and a random-phase approximation. The inner cores of the macroions were modeled as hard spheres, the outer brushes as spherical shells of continuously distributed charge, the microions as point charges, and the solvent as a dielectric continuum. The results show that trapping of counterions inside a spherical polyelectrolyte brush is highly sensitive to variations in the core radius, brush thickness, and Debye screening length of the solution.