Interaction forces between colloidal particles in liquid: theory and experiment

The interaction forces acting between colloidal particles in suspensions play an important part in determining the properties of a variety of materials, the behaviour of a range of industrial and environmental processes. Below we briefly review the theories of the colloidal forces between particles and surfaces including London-van der Waals forces, electrical double layer forces, solvation forces, hydrophobic forces and steric forces. In the framework of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, theoretical predictions of total interparticle interaction forces are discussed. A survey of direct measurements of the interaction forces between colloidal particles as a function of the surface separation is presented. Most of the measurements have been carried out mainly using the atomic force microscopy (AFM) as well as the surface force apparatus (SFA) in the liquid phase. With the highly sophisticated and versatile techniques that are employed by far, the existing interaction theories between surfaces have been validated and advanced. In addition, the direct force measurements by AFM have also been useful in the explaining or understanding of more complex phenomena and in engineering the products and processes occurring in many industrial applications.