Dipolar fluids in complex matrices

Understanding the resulting interplay (or competition) between these interactions is relevant not only from an academic point of view but also from the perspective of adsorption processes in experimental systems. Indeed, dipolar fluid matrix interactions play a central role in purification processes such as liquid chromatography where polar liquids are adsorbed by disordered materials ( omposiyl of molecules with polar headgroups [325]. 

The simplest matrix generating disordered dipolar fields consists of a system of DHS, which are quenched from an equilibrium fluid configuration at quenching temperature Tq. At this ternperatiue, the coupling between two matrix particles is given by 

The effect of the variation of on the stability limits of a polar Stock-mayer fluid, which implies a variation of the dipolar fluid matrix coupling, is illustrated in the upper part of Fig. 7.4. All results correspond to dilute matrices that do not suppress the gas liquid transition but lead to a significant shift of that transition. In particular, the critical temperature decreases with increasing /x,n, whereas the critical density increases. This characteristic effect is referred to as preferential adsorption in other contexts. The replica integral equation results thus demonstrate, at a microscopic level, that polar 

More dramatic effects arise when the perturbation induced by the disordered matrix couples directly to the dipole moments of the fluid particles. Charged matrix particles provide an example. Their impact on a DHS fluid has been studied by Fernaud et al. [323]. They report a significant decrease of the dielectric constant and an enhanced tendency of dipoles to form aggregates at low densities. Another interesting case are dipolar fluid matrix interactions where each fluid particle feels both the dipole fields of its fluid neighbors and the additional dipole fields arising from the adsorbing medium. 

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