DerjaguinLandauVerweyOverbeek

DLVO theory, named after Boris V. Derjaguin and Lev B. Landau, and independently developed by Verwey and Overbeek, is a framework in colloid science that explains the stability of suspensions. It describes the total interaction energy between particles as the sum of van der Waals attraction and electrostatic repulsion from the electrical double layer, summarized by V(h) = V_A(h) + V_R(h).

Van der Waals attraction arises from fluctuations of charge within particles and the medium. The strength is governed by the Hamaker constant, particle size, and geometry, and the attraction typically increases as particles come closer, tending to promote aggregation.

Electrostatic repulsion results from charged surfaces that attract counterions, forming an electrical double layer. The repulsive energy depends on surface potential or charge, ionic strength, dielectric properties, and Debye length; higher salt concentrations compress the double layer and weaken repulsion.

The balance between the attractive and repulsive terms creates an energy landscape with barriers and minima that determine stability. A significant energy barrier can prevent aggregation and keep particles dispersed; reducing the barrier (for example, by increasing ionic strength or introducing multivalent ions) can lead to coagulation or flocculation. Real systems may also involve non-DLVO interactions such as hydration forces or steric stabilization.

Historically, Derjaguin and Landau introduced the attractive component in the 1940s and Verwey and Overbeek added the electrostatic part, forming the DLVO theory. It remains central to predicting colloid stability, sedimentation, coatings, and emulsions, while its limitations—such as neglect of specific ion effects and non-DLVO forces—have spurred various extensions.