Irreversible adsorption of colloidal particles on solid substrates

In this article, we summarize the basic results relative to the field of irreversible deposition processes of colloidal particles on solid surfaces. An irreversible deposition process is defined as a process in which, once adsorbed, a particle can neither diffuse along, nor desorb from the surface. However, some extensions leading to reversible adsorption models are also outlined. First the basic tools used in these studies are introduced, notably the concept of available surface function. General results relative to these processes are then presented. We discuss, in particular, the connection between the reduced variance of the number density fluctuations of adsorbed particles and the available surface function. We then review the main models which were introduced in the literature to account for these processes. They can be divided in two classes: (i) the models which are based entirely on statistical and geometrical grounds. The most widely studied of them is the Random Sequential Adsorption (RSA) model which is discussed in detail. For the processes in which gravity plays an important role one uses the Ballistic Deposition (BD) model. We also present models which are aimed at accounting for the behavior lying between the ballistic deposition and the RSA. (ii) The second type of models corresponds to those which take explicitly the diffusion of the particles in the vicinity of the adsorption plane into account. The results relative to these models, called diffusional models, are discussed in detail. Finally, the last part of the article is devoted to experimental results. We present and discuss in a critical way experimental evidence which seems to indicate the validity of the RSA and ED models. (C) 2000 Elsevier Science B.V. All rights reserved.