Interactions Between Colloidal Particles

The pair potential of colloidal particles, i.e. the potential energy of interaction between a pair of colloidal particles as a function of separation distance, is calculated from the linear superposition of the individual energy curves. When this was done using the attractive potential calculated from London dispersion forces, Fa, and electrostatic repulsion, Ve, the theory was called the DLVO Theory (from Derjaguin, Landau, Verwey and Overbeek). Here we will use the term to include other potentials, such as those arising from depletion interactions, Kd, and steric repulsion, Vs, and so we may write the total potential energy of interaction as 

It is the convention to denote attractive potentials as negative and repulsive ones as positive. 

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Colloidal particles can be seen as large, model atoms . In what follows we assume that particles with a typical radius <3 = lOO nm are studied, about lO times as large as atoms. Usually, the solvent is considered to be a homogeneous medium, characterized by bulk properties such as the density p and dielectric constant t. A full statistical mechanical description of the system would involve all colloid and solvent degrees of freedom, which tend to be intractable. Instead, the potential of mean force, V, is used, in which the interactions between colloidal particles are averaged over... 

The interactions between colloidal particles (see section C2.6.4) are central to tire understanding of suspension behaviour. Aitlrough most work has had to rely on ratlrer indirect ways to characterize tlrese interactions, novel teclmiques are emerging tlrat access tlrese interactions more directly. 

Surfaces can be characterized using scaiming probe microscopies (see section B1.19). In addition, by attaching a colloidal particle to tire tip of an atomic force microscope, colloidal interactions can be probed as well [27]. Interactions between surfaces can be studied using tire surface force apparatus (see section B1.20). This also helps one to understand tire interactions between colloidal particles. 

Hall, D.G., 1972. Thermodynamic treatment of some factors affecting the interaction between colloidal particles. Journal of the Chemical Society Faraday Transactions, 68(2), 2169-2182. 

Figure 6.3. Schematic potential energy curve describing the interactions between colloidal particles. The overall potential is a sum of an electrostatic repulsive term which arises due to any charged groups on the surface of the particle and the attractive van der Waals term.

Pierre M. Adler, Ali Nadim, and Howard Brenner, Rheological Models of Suspensions Stanley M. Englund, Opportunities in the Design of Inherently Scfer Chemical Plants H. J. Ploehn and W. B. Russel, Interactions between Colloidal Particles and Soluble Polymers... 

H. J. Ploehn and W. B. Russel, Interactions between Colloidal Particles and Soluble Polymers... 

B. V. Deiyaguin and L. V. Landau, The Basic Theory of Interactions Between Colloid Particles, Acta Physicochim. 44 633 (1941). 

Interactions between Colloidal Particles Covered by Biopolymer... 

Overbeek, J. Th. G., The Interaction Between Colloidal Particles. In Colloid Science, Vol. 1 (H. R. Kruyt, Ed.), Elsevier, Amsterdam, Netherlands, 1952b, pp. 245-277. (See the annotation under Kruyt 1952). 

What is the Gibbs free energy of an electric double layer The energy of an electric double layer plays a central role in colloid science, for instance to describe the properties of charged polymers (polyelectrolytes) or the interaction between colloidal particles. Here, we only give results for diffuse layers because it is simpler and in most applications only the diffuse layer is relevant. The formalism is, however, applicable to other double layers as well. 

The major problem in calculating the van der Waals interaction between colloidal particles is that of evaluating the Hamaker constant, A. Two methods are available. 

Polyelectrolyte molecules affect in a more complicated manner than the neutral ones the bridging interactions between colloidal particles because they influence through their dissociation the electrical potential of the electrical double layer [24 27] which, in turn, affects the conformation of the chains and the overall electrostatic interaction. 

N. O. Mchedlov-Petrossyan, V. K. Klochkov, G. V. Andrievsky, and A. A. Ishchenko, Interaction between colloidal particles of C60 hydrosol and cationic dyes, Chem. Phys. Lett. 341, 237-244 (2001). 

On the basis of the disjoining pressure (44), an electrostatic part of the pair interaction between colloidal particles can be computed as... 

The classical DLVO (Derjaguin-Landau-Verwey-Overbeek) theory (Derjaguin and Landau, 1941 Yerwey and Overbeek, 1948) states that the stability of a colloidal system essentially depends on two independent interactions between colloidal particles van der Waals attractions and electrostatic repulsion ... 

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