Effect of line tension on axisymmetric nanoscale capillary bridges at the liquid-vapor equilibrium

Abstract

The effect of line tension on the axisymmetric nanoscale capillary bridge between two identical substrates with convex, concave and flat geometry at the liquid-vapor equilibrium is theoretically studied. The modified Young's equation for the contact angle, which takes into account the effect of line tension is derived on a general axisymmetric curved surface using the variational method. Even without the effect of line tension, the parameter space where the bridge can exist is limited simply by the geometry of substrates. The modified Young's equation further restricts the space where the bridge can exist when the line tension is positive because the equilibrium contact angle always remain finite and the wetting state near the zero contact angle cannot be realized. It is shown that the interplay of the geometry and the positive line tension restricts the formation of capillary bridge.

Direct measurement of curvature-dependent surface tension of an alcohol nanomeniscus

“…As shown, larger discrepancies between the observed and predicted values occur at lower saturation ratio p/p . It implies that the curvature-dependent surface tension has to be incorporated, since careful consideration of other factors, including nonideality of the fluid and contactangle change due to the line-tension effect at the threephase contact line [39][40][41], fails to fully explain the discrepancies. Especially, the discrepancy actually increases with contact angle increase within the range 0 < θ < π/2, but decreases for vanishing contact angle.…”

Direct Measurement of Curvature-Dependent Surface Tension in a Capillary-Condensed Alcohol Nanomeniscus

“…As shown, larger discrepancies between the observed and predicted values occur at lower saturation ratio p/p 0 . It implies that the curvature-dependent surface tension has to be incorporated, since careful consideration of other factors, including nonideality of the fluid and contactangle change due to the line-tension effect at the threephase contact line [36][37][38], fails to fully explain the discrepancies. Especially, the discrepancy actually increases with contact angle increase within the range 0 < θ < π/2, but decreases for vanishing contact angle.…”