Confining surfaces, interaction

Let us consider an V-component fluid in a volume V, at temperature T, and at chemical potentials /r = mi, > Mv - The fluid is in contact with an impermeable solid surface. We assume that the fluid particles interact between themselves via the pair potential denoted by u pir), and interact with the confining surface via the potential (a,f3= 1,2,. ..,V). The potential v ir) contains a hard-wall term to ensure that the solid surface is impermeable. For the sake of convenience, the hard-wall term is assumed to extend into the bulk of the solid [46,47], such that the Boltzman factor (r), and the local density Pa r) are cutoff at a certain distance z = z, ... 

The popular and well-studied primitive model is a degenerate case of the SPM with = 0, shown schematically in Figure (c). The restricted primitive model (RPM) refers to the case when the ions are of equal diameter. This model can realistically represent the packing of a molten salt in which no solvent is present. For an aqueous electrolyte, the primitive model does not treat the solvent molecules exphcitly and the number density of the electrolyte is umealistically low. For modeling nano-surface interactions, short-range interactions are important and the primitive model is expected not to give adequate account of confinement effects. For its simphcity, however, many theories [18-22] and simulation studies [23-25] have been made based on the primitive model for the bulk electrolyte. Ap-phcations to electrolyte interfaces have also been widely reported [26-30]. 

Attachment of a single segment of the polymer chain is sufficient to confine the molecule to the layer of solution adjacent to the adsorbing surface. The solid exerts very little influence on the polymer molecule as a whole in such a case. In fact, the overall spatial extension of the polymer chain is expected to be about the same as that of an isolated molecule in this situation. The polymer-solvent interaction plays a more important role than the polymer-surface interaction in determining the thickness of the adsorbed layer in this case. This is only one of the relative interaction combinations possible, but it is the one that we consider in the greatest detail. As the number of polymer segments actually attached to the surface increases, the influence of the surface causes the spatial extension of the adsorbed chains to decrease. 

Along with the surface interactions, the chain conformation that is imposed by the confined geometry and by the film preparation strongly affects the swelling behavior of polymer films [119, 169-171]. 

When the confined surfaces suffer from a weak interaction with block copolymer, either parallel or vertical lamellar structures for AB diblock copolymer systems under flat and curved confinements could exhibit, as shown in Figure 27. From theoretical predictions (Turner, 1992 Walton et al., 1994) and simulations (Wang et al., 2000 Yin et al., 2004), the frustration between d and L0 could result in the alternative appearance of parallel lamellar and vertical lamellar structures under flat confinements. A question is naturally arisen can both concentric cylinder barrel and sector column structures appear under the curved confinement ... 

An additional control has been performed for antibody. It is known that the clone 4 and clone 5 bind to the Mb molecule simultaneously (27). If antibody is adsorbed to the PDMS surface initially, introduced into the solution, some of the clone 4 antibody adsorbed to the PDMS surface will remain active and will bind Mb from solution. The bound Mb is thus surface-confined without interacting with the PDMS surface and in an orientation that the clone 5... 

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