Tension at the Surface: Which Phase Is More Important, Liquid or Vapor?

Abstract

Tension at the surface is a most fundamental physicochemical property of a liquid surface. The concept of surface tension has widespread implications in numerous natural, engineering and biomedical processes. Research to date has been largely focused on the liquid side; little attention has been paid to the vapor—the other side of the surface, despite over 100 years of study. However, the question remains as to whether the vapor plays any role, and to what extent it affects the surface tension of the liquid. Here we show a systematic study of the effect of vapor on the surface tension and in particular, a surprising observation that the vapor, not the liquid, plays a dominant role in determining the surface tension of a range of common volatile organic solutions. This is in stark contrast to results of common surfactants where the concentration in the liquid plays the major role. We further confirmed our results with a modified adsorption isotherm and molecular dynamics simulations, where highly structured, hydrogen bonded networks, and in particular a solute depletion layer just beneath the Gibbs dividing surface, were revealed.

A multi-scale perspective of gas transport through soap-film membranes

“…Þ ), and d is the thickness parameter for the interface. As in previous studies, 30,31 we computed the "10-90" thickness parameter representing the length-scale over which the density decays from 90 to 10% of the bulk value. This number reported in Table 1 is 2.1972d yielding a value of 17.8 Å.…”

Theoretical description of 2D-cluster formation of nonionic surfactants at the air/water interface

“…The transition from spherical to rodlike micelles was detected at a certain value of the aggregation number, which increases with lengthening the surfactant alkyl chain. The results of study [94] are of interest because, contrary to all preconceived ideas, they show the defining impact of the vapor phase on the interfacial tension value in the case of volatile surfactant. The interaction energy between the surfactant molecules (cohesion) and between surfactants and water (adhesion) was analyzed in the investigations [96,97].…”

“…[86,[92][93][94][95], the MD method was used for the assessment of surface tension and CMC of different amphiphiles. Modeling of the ethanol behavior, done by Tarek et al [86], gives the adequate orientation of the alcohol molecule at the interface with the hydrophilic part in the water phase and the hydrophobic in the air.…”

Kongresse – Symposien – Seminare – Messen

“…In one word, although it has been widely recognized that the study of protein adsorption is very important in the realm of materials design, little is understood at this time, and all‐atom molecular dynamics (MD) simulations are expected to have the potential to address this problem by investigating the adsorption behaviors at the atomic level 19. Recently, N. Patra et al studied the folding of planar graphene nanostructures activated and guided by water droplets,20 which further excites people's interest in the bioinorganic interfacial systems involving biomacromolecules 21, 22. Nowadays, it is generally considered that proteins are attracted or repelled by charged surfaces and adsorb strongly to hydrophobic surfaces.…”