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Canonical ensemble molecular dynamics and Monte Carlo simulations have been performed to study the vapor/liquid coexistence in a hard-core fluid with an attractive Yukawa interaction. Coexisting densities and pressure along the... more
Canonical ensemble molecular dynamics and Monte Carlo simulations have been performed to study the vapor/liquid coexistence in a hard-core fluid with an attractive Yukawa interaction. Coexisting densities and pressure along the vapor/liquid coexistence line for different ranges of attractive interaction have been evaluated and found to agree well with the Gibbs ensemble Monte Carlo data reported in the literature. To obtain surface tension, the normal and tangential components of the pressure tensor have been calculated during simulations by using a hybrid molecular dynamics algorithm (which combines the hard-core and continuous forces) and by using an original numerical algorithm for the hard-core contribution to the virial in Monte Carlo simulations. We found that surface tension is strongly dependent on the range of attractive interaction, i.e., it drops when the attraction becomes short-ranged. The relation of the attractive hard-core Yukawa potential to the spherically-truncated Lennard-Jones potential in terms of the interfacial properties is discussed.
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This paper discusses the role of the structural disjoining pressure exerted by nanoparticles on the spreading of a liquid film containing these particles. The origin of the structural disjoining pressure in a confined geometry is due to... more
This paper discusses the role of the structural disjoining pressure exerted by nanoparticles on the spreading of a liquid film containing these particles. The origin of the structural disjoining pressure in a confined geometry is due to the layering of the particles normal to the confining plane and has already been traced to the net increase in the entropy of the system in previous studies. In a recent paper, Wasan and Nikolov (Nature, 423 (2003) 156) pointed out that the structural component of the disjoining pressure is strong enough to move a liquid wedge; this casts a new light on many applications—most notably, detergency. While the concept of spreading driven by the disjoining pressure is not new, the importance of the structural disjoining pressure arises from its long-range nature (as compared to the van der Waals' force), making it an important component of the overall force balance near the contact line. In this paper, we report on a parametric study of the spreading phenomena by examining the effects of nanoparticle size, concentration and polydispersity on the displacement of an oil–aqueous interface with the aqueous bulk containing nanoparticles. The solution of the extended Laplace–Young equations for the profile of the meniscus yields the position of the nominal contact line under the action of the structural disjoining pressure. Simulations show that the displacement of the contact line is greater with a high nanoparticle volume fraction, small particles for the same volume fraction, monodispersed (in size) particles rather than polydispersed particles and when the resisting capillary pressure is small, i.e., when the interfacial tension is low and/or the radius of the dispersed phase drop/bubble is large.