Self-assembled nanoparticle-coated interfaces: Capillary pressure, shell formation and buckling.
KAUST DepartmentEarth Science and Engineering Program
Earth Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
Online Publication Date2020-07-27
Print Publication Date2021-01
Permanent link to this recordhttp://hdl.handle.net/10754/664594
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AbstractHYPOTHESIS:Particle accumulation at liquid-liquid or liquid-gas interfaces can significantly alter capillary behavior and give rise to unusual interfacial phenomena including the asymmetric macroscopic mechanical response of the interface. EXPERIMENTS:This study explores the accumulation of cetyltrimethylammonium bromide-modified nanoparticles at fluid interfaces and the subsequent mechanical response of nanoparticle-coated droplets during contraction and expansion. Droplet tests involve the simultaneous recording of the droplet shape and the capillary pressure. Complementary single-pore experiments examine the response of particle-coated interfaces as they traverse a pore constriction. FINDINGS:Interfaces promote order. The time-dependent nanoparticle accumulation at the interface is diffusion-controlled. The nanoparticle coated droplets can sustain negative capillary pressure before they buckle. Buckling patterns strongly depend on the boundary conditions: non-slip boundary conditions lead to crumples while slip boundary conditions result in just a few depressions. The particle-coated interface exhibits asymmetric behavior in response to particle-level capillary forces: an "oil droplet in a nanofluid bath" withstands a significantly higher capillary pressure difference than a "nanofluid droplet in an oil bath". A first-order equilibrium analysis of interaction forces explains the asymmetric response. Single-constriction experiments show that the formation of particle-coated interfaces has a pronounced effect on fluid displacement in porous media.
CitationLiu, Q., Sun, Z., & Santamarina, J. C. (2021). Self-assembled nanoparticle-coated interfaces: Capillary pressure, shell formation and buckling. Journal of Colloid and Interface Science, 581, 251–261. doi:10.1016/j.jcis.2020.07.110
SponsorsSupport for this research was provided by the KAUST endowment. G. Abelskamp edited the manuscript. We are grateful to the anonymous reviewers for their detailed reviews and insightful observations.
Except where otherwise noted, this item's license is described as This is an open access article under the CC BY license .
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