Clustering effects on the diffusion of patchy colloids in disordered porous media

Abstract

Enskog theory is extended for the description of the self-diffusion coefficient of patchy colloidal fluid in disordered porous media. The theory includes the contact values of fluid-fluid and fluid-matrix pair distribution functions that are modified to include the dependence from the so-called probe particle porosity, φ, in order to correctly describe the effects of trapping the fluid particles by a matrix. The proposed expressions for the modified contact values of fluid-fluid and fluid-matrix pair distribution functions include three terms. Namely, a hard sphere contribution obtained by us in the previous work [Holovko M. F., Korvatska M. Ya., Condens. Matter Phys., 2020, 23, 23605], the depletion contribution connected with the cluster-cluster and cluster-matrix repulsion and the intramolecular correlation inside the cluster. It is shown that the last term leads to a remarkable decrease of the self-diffusion coefficient at a low fluid density. With a decreasing matrix porosity, this effect becomes weaker. For intermediate fluid densities, the depletion contribution leads to an increase of the self-diffusion coefficient in comparison with the hard sphere fluid. For a sufficiently dense fluid, the self-diffusion coefficient strongly decreases due to a hard sphere effect. The influence of the cluster size and the type of clusters as well as of the parameters of porous media is investigated and discussed in detail.

Dimerizing hard spherocylinders in porous media

“…where 𝑋 = 𝜌 10 /𝜌 1 is the fraction of monomers, 𝐹 = exp(𝛽𝜖 1 ) − 1, and 𝐾 is the geometric multiplier, determined by the volume of overlap of the two interactive bonding sites [55]. The contact value of the binary function of hard spherocylinders 𝑔 cont HSC will be approximated by the corresponding contact value of hard spheres, which, with the help of previous works [8,9], can be presented in the following form:…”

“…The patchy colloidal system was considered to be confined in a random porous media. The influence of porous media on the phase behaviour, percolation, and dynamical properties of confined patchy colloidal fluids were considered [8,9].…”