TY - JOUR

T1 - The overlapping surface layers and the disjoining pressure in a small droplet

AU - Shchekin, Alexander K.

AU - Lebedeva, Tatiana S.

AU - Suh, Donguk

PY - 2019/8/5

Y1 - 2019/8/5

N2 - The square-gradient density functional theory has been used to study the bulk pressure and normal/tangential components of the local pressure tensor at several chemical potential values in a small droplet without and with a completely wettable solid core and a flat liquid thin film on a solid substrate. The Lennard-Jones fluid with the Carnahan-Starling model for the hard-sphere contribution to intermolecular interactions and mean-field attraction contribution have been used to describe the condensate. The interaction between the solid spherical core (and flat substrate) molecules and the condensate molecules has been taken to be stronger than the condensate-condensate interaction. The inhomogeinity within the curved liquid film on a solid core (and within a liquid film on flat substrate) has been found to be an effect of the interaction (or overlapping) of the interfacial layers of the solid-liquid and liquid-vapor interfaces. The disjoining pressure for a flat liquid thin film on a solid substrate in the undersaturated vapor has been computed for various film thicknesses as the difference between bulk values of the pressures for vapor and liquid phases. This disjoining pressure has been compared with that of small droplets condensed on solid cores found through the thermodynamic and mechanical routes for a range of values of the droplet and core sizes. The disjoining pressure was smaller for a curved film and was dependent on the solid core size.

AB - The square-gradient density functional theory has been used to study the bulk pressure and normal/tangential components of the local pressure tensor at several chemical potential values in a small droplet without and with a completely wettable solid core and a flat liquid thin film on a solid substrate. The Lennard-Jones fluid with the Carnahan-Starling model for the hard-sphere contribution to intermolecular interactions and mean-field attraction contribution have been used to describe the condensate. The interaction between the solid spherical core (and flat substrate) molecules and the condensate molecules has been taken to be stronger than the condensate-condensate interaction. The inhomogeinity within the curved liquid film on a solid core (and within a liquid film on flat substrate) has been found to be an effect of the interaction (or overlapping) of the interfacial layers of the solid-liquid and liquid-vapor interfaces. The disjoining pressure for a flat liquid thin film on a solid substrate in the undersaturated vapor has been computed for various film thicknesses as the difference between bulk values of the pressures for vapor and liquid phases. This disjoining pressure has been compared with that of small droplets condensed on solid cores found through the thermodynamic and mechanical routes for a range of values of the droplet and core sizes. The disjoining pressure was smaller for a curved film and was dependent on the solid core size.

KW - Density profile

KW - Disjoining pressure

KW - Droplets

KW - Films

KW - Nucleation

KW - Pressure tensor

KW - THIN-FILMS

KW - THERMODYNAMIC CHARACTERISTICS

KW - LIQUID

KW - SIZE

KW - LENGTH

KW - TENSION

KW - DEPENDENCE

KW - HETEROGENEOUS NUCLEATION

KW - MECHANICAL EQUILIBRIUM

KW - EQUATION

UR - http://www.scopus.com/inward/record.url?scp=85065495357&partnerID=8YFLogxK

U2 - 10.1016/j.colsurfa.2019.04.071

DO - 10.1016/j.colsurfa.2019.04.071

M3 - Article

AN - SCOPUS:85065495357

VL - 574

SP - 78

EP - 85

JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects

JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects

SN - 0927-7757

ER -