Effect of retardation in the dispersion forces between spherical particles

• Published in: Journal of colloid and interface science Vol. 355; no. 2; pp. 417 - 422
• Main Authors: Boltachev, G.Sh, Volkov, N.B., Nagayev, K.A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15-03-2011
• Subjects: Approximation; Attraction; Colloids; Dispersions; Empirical analysis; energy; Energy of formation; Hamaker formula; Intermolecular potential; Laws; Mathematical models; physicochemical properties; Retardation effect; Intermolecular potential; Colloids; Hamaker formula; Retardation effect
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2010.12.050

For particles with a diameter of 3
μm the retardation effect reduces about twice the distance, where van der Waals attractive force predominates over the gravitational force.
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► The model intermolecular potential has been proposed, which takes into account the retardation effect and makes possible to approximate the real intermolecular potentials. ► The generalization of known Hamaker formula for the attractive energy of macroscopic particles, which takes into account the retardation effect, has been derived rigorously. ► It has been found that neglecting the retardation effect can give the energy and force values overestimated more than one order of magnitude.
A model potential for intermolecular attractive forces, which takes into account the retardation effect at large distances, is proposed. This potential is shown to be capable of approximating arbitrary empirical potentials of intermolecular interactions. For this model potential, the generalization of the known Hamaker formula for the attractive energy of macroscopic particles is derived. A comparison of the laws of attraction of particles of spherical shapes, when the retardation effect is taken into account as realized in the model discussed, with the classical Hamaker result neglecting such dependence is carried out.