A perspective on the interfacial properties of nanoscopic liquid drops

Abstract

The structural and interfacial properties of a nanoscopic liquid drops are assessed by means of mechanical, thermodynamical, and statistical mechanical approaches that are discussed in detail, including original developments at both the macroscopic level and the microscopic level of density functional theory (DFT). We emphasize that any approach, such as classical nucleation theory, which is based on a purely macroscopic viewpoint does not lead to a reliable representation when the radius of the drop becomes microscopic. The so-called mechanical route which corresponds to a molecular-level extension of the macroscopic theory of elasticity, and is particularly popular in molecular dynamics simulation, also appears to be unreliable due to the inherent ambiguity in the definition of the microscopic pressure tensor, an observation which has been known for decades but is frequently ignored. In this vein, we propose a non-local mean-field DFT for Lennard-Jones (LJ) fluids to examine drops of varying size. A comparison of the predictions of our DFT with the recent simulation data based on a second-order fluctuation analysis [J. G. Sampayo et al., JCP 132, 141101 (2010)] reveals the consistency of the two treatments. This observation points out the significance of fluctuation effects in small drops, in contrast to what one observes in the case of planar interfaces which are governed by the laws of mechanical equilibrium. A small negative Tolman length and a non-monotonic behaviour of the surface tension with the drop radius are predicted for the LJ fluid. Finally, the limits of a validity of the Tolman approach, the effect of the range of the intermolecular potential, and the behaviour of bubbles are briefly discussed.

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• Wetting of Curved Surfaces
• Evidence for the role of fluctuations in the thermodynamics of nanoscale drops and the implications in computations of the surface tension
• Modification of the classical nucleation theory based on molecular simulation data for surface tension, critical nucleus size, and nucleation rate
• The excess equimolar radius of liquid drops
• Non-analytic curvature contributions to solvation free energies: influence of drying
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• Phase separation kinetics in compressible polymer solutions: Computer simulation of the early stages
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Cited by in corpus (25)

• Capillary condensation under atomic-scale confinement
• Curvature-dependence of the liquid-vapor surface tension beyond the Tolman approximation
• The influence of the liquid slab thickness on the planar vapor-liquid interfacial tension
• The Young-Laplace equation for a solid-liquid interface
• A perspective on the microscopic pressure (stress) tensor: history, current understanding, and future challenges
• Enhanced wavelength-dependent surface tension of liquid-vapour interfaces
• Density Functional Theory of a Curved Liquid-Vapour Interface: Evaluation of the rigidity constants
• Interfacial free energy and Tolman length of curved liquid-solid interfaces from equilibrium studies
• Introduction to colloidal dispersions in external fields
• Surface tension of supercooled water nanodroplets from computer simulations
• Equivalence between condensation and boiling in a Lennard Jones fluid
• Free Energy Barriers for Crystal Nucleation from Fluid Phases
• A Mesoscale Perspective on the Tolman Length
• Sedimentation of a two-dimensional colloidal mixture exhibiting liquid-liquid and gas-liquid phase separation: a dynamical density functional theory study
• Structure of liquid--vapor interfaces: perspectives from liquid state theory, large-scale simulations, and potential grazing-incidence X-ray diffraction
• Surface tension of small bubbles and droplets and the cavitation threshold
• The Intrinsic Fragility of the Liquid-Vapor Interface: A Stress Network Perspective
• Hydrodynamics Across a Fluctuating Interface
• The Young-Laplace's equation for solid
• Reply to Comment on: "Are stress-free membranes really 'tensionless'?"
• Interfacial thermodynamics of spherical nanodroplets: Molecular understanding of surface tension via hydrogen bond network
• Classical density functional theory for nanoparticle-laden droplets
• Uniform distributions in nonuniform systems: Wall potentials generating constant density profiles in classical density functional theory
• Fluctuation-Dissipation Framework for Size-Dependent Surface Tension
• Reexamination of Tolman's law and the Gibbs adsorption equation for curved interfaces