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arXiv 2110.04583cond-mat.soft
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无序多孔介质中块状胶体扩散的成簇效应

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

M. F. Holovko, M. Ya. Korvatska

摘要:

将Enskog理论推广到描述无序多孔介质中斑片状胶体流体的自扩散系数。该理论包括流体-流体和流体-基质对分布函数的接触值,其被修改以包括来自所谓的探针颗粒孔隙度$ϕ$的依赖性,以便正确地描述由基质捕获流体颗粒的效果。流体-流体和流体-矩阵对分布函数的修正接触值的建议表达式包括三项。也就是说,我们在以前的工作[Holovko M。F.、科瓦茨卡湾是的,康登斯物质物理学,2020,23,23605],耗尽贡献与团簇-团簇和团簇-基质排斥以及团簇内部的分子内关联有关。结果表明,最后一项导致显着降低的自扩散系数在低流体密度。随着基质孔隙度的降低,这种影响变得越来越弱。对于中间流体密度,耗尽的贡献导致增加的自扩散系数相比,硬球流体。对于足够稠密的流体,由于硬球效应,自扩散系数强烈降低。团簇的大小和类型以及多孔介质的参数的影响进行了研究和详细讨论。

英文摘要:

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.

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