INTERACTION ENERGY AND FORCE OF SPHERICAL COLLOIDAL PARTICLES AT MODERATE POTENTIAL

Using the definition of the effective reduced surface potential and re sorting to improved Derjaguin method, we derive the formula for the in teraction energy and force of identical and dissimilar spherical collo idal particles, valid up to the moderate potential. The agreement with exact numerical values is considerably improved on providing the surf ace potential less than or equal to 100 mV (for identical) and less th an or equal to 75 mV (for dissimilar): the maximum relative errors are less than +/-10%. For the identical and dissimilar spherical particle s, our formula are best approximate expressions at present.