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Dynamic spreading of droplets containing nanoparticles

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Original languageEnglish
Article number056315
Number of pages9
JournalPhysical Review E - Statistical, Nonlinear and Soft Matter Physics
Volume76
Issue number5
DOIs
Publication statusPublished - Nov 2007

Abstract

Recent experiments and models for the spreading of liquids laden with nanoparticles have demonstrated particle layering at the three-phase contact line; this is associated with the structural component of the disjoining pressure. Effects driven by structural disjoining pressures occur on scales longer than the diameter of a particle, below which other disjoining pressure components such as van der Waals and electrostatic forces are dominant. Motivated by these experimental observations, we investigate the dynamic spreading of a droplet laden with nanoparticles in the presence of structural disjoining pressure effects. We use lubrication theory to derive evolution equations for the interfacial location and the concentration of particles. These equations account for the presence of the structural component of the disjoining pressure for film thicknesses exceeding the diameter of a nanoparticle; below such thicknesses, van der Waals forces are assumed to be operative. The resulting evolution equations, for the particle motion and free surface position, are solved allowing for the viscosity to vary as a function of nanoparticle concentration. The results of our numerical simulations demonstrate qualitative agreement with experimental observations of a "step" emerging from the contact line. The results are also relevant to a wide range of other phenomena involving layering, or terraced spreading of nanodroplets, or stepwise thinning of micellar thin films.

    Research areas

  • THIN LIQUID-FILMS, HARD-SPHERE FLUID, ANIONIC SURFACTANT SOLUTIONS, DISJOINING PRESSURE, PATTERN-FORMATION, DEPLETION FORCES, WETTING FILMS, RUPTURE, STABILITY, SYSTEMS

ID: 1669417