Thermodynamics, dynamics, and kinetics at liquid-fluid and fluid-solid interfaces

This article covers thermodynamic, dynamic, and kinetic models that are suitable for the analysis of wetting, adsorption, and related interfacial phenomena in colloidal and multiphase systems. Particular emphasis is made on describing crucial physical assumptions and the validity range of the described theoretical approaches and predictive models. The classical sharp interface treatment of thermodynamic systems where a perfectly smooth surface is assumed to separate homogeneous phases can present significant limitations when analyzing systems that are subject to thermal motion and present multiple metastable states caused by interfacial heterogeneities of nanoscale dimensions. Mesoscopic approaches such as stochastic Langevin dynamics can extend the application of sharp interface models to a wide variety of systems exhibiting metastability as they undergo thermal motion. For such metastable systems, dynamic and kinetic equations can describe the evolution of observable (macroscopic) variables as the system approaches thermodynamic equilibrium. Sufficiently close to equilibrium, Kramers theory of thermally activated escape from metastable states can be effectively employed to describe diverse wetting and interfacial processes via kinetic equations. Future directions for further advancement and application of thermodynamic, dynamic, and kinetic models are briefly discussed in the context of current technological developments involving nanoparticles, nanofluidics, and nanostructured surfaces.