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21.

Entropic wetting and the fluid-fluid interface of a model colloid-polymer mixture J. M. Brader, R. Evans, M. Schmidt, and H. Löwen, J. Phys. Condens. Matter 14, L1 (2002). Locate in [bare] [illustrated] list. Get [full paper] as pdf. Abstract. A recent density functional theory is used to investigate the free interface between demixed fluid phases in a model colloid-polymer mixture. Both the colloid and polymer density profiles oscillate on the colloid-rich side of the interface, provided the polymer reservoir packing fraction eta_p^r is sufficiently high. Results for the surface tension are in reasonable agreement with experiment. When the mixture is adsorbed against a hard wall, entropic depletion effects give rise to a wetting transition whereby the colloid-rich phase wets completely. Prior to complete wetting we find three layering transitions, the first of which extends far into the single-phase region. This pattern of surface phase transitions is very different fromthat observed for simple one-component fluids at planar substrates. [figures] Read the [full paper] as pdf.

Fluid interfaces

Colloid-polymer mixtures display fluid-fluid interfaces [21] [44], relevant for laser-induced condensation [35], capillary condensation [43] and evaporation [48], immersion in porous media [41], the appearance of the floating liquid phase [52], the competition between sedimentation and phase coexistence [51], tension at a substrate [45], the experimental observation of thermal capillary waves [47], and the contact angle of the liquid-gas interface and a wall [50]. In colloidal rod-sphere mixtures fluid-fluid interfaces were investigated with theory [30] and simulation [42]. Hard sphere fluids were considered at surfaces of porous media [37], in random fiber networks [39], and in one dimensional cases [46].

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