Wetting and Nonwetting near a Tricritical Point.

The dihedral contact angles between interfaces in three-fluid-phase equilibria must be continuous functions of the bulk thermodynamic fields. This general argument, which we propose, predicts a nonwetting gap in the phase diagram, challenging the common belief in "critical-point wetting," even for short-range forces. A demonstration is provided by exact solution of a mean-field two-density functional theory for three-phase equilibria near a tricritical point (TCP).

Three-phase equilibria in density-functional theory: Interfacial tensions.

A mean-field density-functional model for three-phase equilibria in fluids (or other soft condensed matter) with two spatially varying densities is analyzed analytically and numerically. The interfacial tension between any two out of three thermodynamically coexisting phases is found to be captured by a surprisingly simple analytic expression that has a geometric interpretation in the space of the two densities. The analytic expression is based on arguments involving symmetries and invariances.

Efficiency at Maximum Power of Irreversible Engines with Asymmetric Nonlinear Flux-Force Relations.

The efficiency at maximum power (EMP) is investigated for classical irreversible thermal or chemical model engines. The heat or particle transport is governed by flux-force relations of the general power-law type. Special attention is given to engines that feature asymmetric transport laws, one for input (of heat or particles) and a different one for output.

Contact line of adsorbed colloid-polymer droplets in theory and experiment.

The contact line between the colloid-rich bulk liquid and an adsorbed thin film in colloid-polymer mixtures (CPM) is studied by means of an interface displacement model. The interface displacement profiles are compared to laser scanning confocal microscopy (LSCM) images. The mixtures consist of poly(methylmetacrylate) (PMMA) colloids and polystyrene (PS) polymers with polymer-to-colloid size ratio q = 1.

Apparent First-Order Wetting and Anomalous Scaling in the Two-Dimensional Ising Model.

The global phase diagram of wetting in the two-dimensional Ising model is obtained through the exact calculation of the surface excess free energy. In addition to a surface field for inducing wetting, a surface-coupling enhancement is also included. The wetting transition (of second order) is critical for any finite ratio of surface coupling J_{s} to bulk coupling J, and becomes of first order in the limit J_{s}/J→∞.