Cooperative adsorption of network forming fluids onto crystalline surfaces: Structure and connectivity of the interface

Abstract

Effects of weak surface fields on the density profiles and adsorption of a confined fluid near bulk criticality A comparison of density functional and integral equation theories vs Monte Carlo simulations for hard sphere associating fluids near a hard wall Density profiles and first layer adsorption isotherms of a network forming fluid near a crystalline surface are investigated using the Percus-Yevick approximation for the associative Henderson-Abraham-Barker ͑HAB͒ equation. The fluid molecule is represented as a hard sphere with four independent attractive sites. The surface is described as a hard wall with a lattice of adsorbing sites. It is shown that the association induces a new type of cooperativity related to a bridging between the adsorbing sites due to tree-like clusters adsorption. The density profiles calculated exhibit reasonably good agreement with the Monte Carlo computer simulation data. The connectivity properties of the interface are studied and an interfacial percolation threshold is predicted to exist. The mean thickness of the adsorbed layer and the connectedness wall-particle correlation functions are calculated via the connectivity analogue of the HAB equation. It is shown that the adlayer may become infinitely thick with the mean cluster size S in the bulk being finite.

Clustering as a Mechanism of Enhanced Adsorption

“…This means that the adsorbate has an additional (energetic and entropic) impact from its bulk, which induces a correlation for the adsorbed species. The correlation through the bulk is particularly pronounced when the pair interaction in the fluid is attractive enough to induce the clustering [6,7]. Then, the intra-cluster correlation, arising due to the cluster connectivity, enhances the adsorption in comparison with the monomeric case.…”

On the mechanism of negative compressibility in layered compounds

“…The effects of directional attractive forces leading to the formation of networks (specific for hydrogen bonded liquids, such as water) are neglected for the moment. If necessary these phenomena can be taken into account using the methods developed in 9 . In the simplest excluded volume approximation the bulk equation of state is…”

The Multi-Density Integral Equation Approach in the Theory of Complex Liquids

“…To this end, the associative analogue of the Henderson-Abraham-Barker approach [54] was formulated [55] and it was applied to describe dymerizing fluids [55][56][57], polymers [58,59], the network forming fluids [60] close to a hard and adhesive surfaces and ionic fluids close to a charged wall [61]. The developed approach was also applied to describe the adsorption of polymers [58,62,63] and network forming fluids [64] onto crystalline surfaces. It was shown that the intramolecular correlations in polymer chains lead to the cooperative increase in the surface coverage which takes place under the conditions of a strongly diluted case.…”