Certain fluorinated ion-exchange membranes, when swollen and suitably plated by conducting electrodes, display a spontaneous curvature increasing with the applied field E (1) . There is also an inverse effect, where an imposed curvature induces an electric field (in open circuit conditions). We present here a compact description of these effects in the linear regime, and in static conditions: this is based on linear irreversible thermodynamics, with two driving forces (E and a water pressure gradient p ∇ ) and two fluxes (electric current and water current). We also give some qualitative estimates of the three Onsager coefficients which come into play.
It has been shown that a water drop can bounce persistently, when thrown on a super-hydrophobic substrate. We present here scaling arguments which allow us to predict the maximal deformation and the contact time of the drop. This approach is completed by a model describing the flow inside the drop, and by original experimental data.c EDP Sciences
We describe how a wetting liquid brought into contact with a forest of micropillars impregnates this forest. Both the driving and the viscous forces depend on the parameters of the texture (radius b and height h of the pillars, pitch p of the network) and it is found that two different limits characterize the dynamics of wicking. For small posts (h < p), the film progresses all the faster since the posts are high, allowing a simple control of this dynamics. For tall pillars (h > p), the speed of impregnation becomes independent of the pillar height, and becomes mainly fixed by the radius of the posts.
We consider microscopic contact states of a drop deposited
on textured rough surfaces. The energies of three possible
(meta)stable wetting states are compared and the lowest
energy state is regarded as the “phase”. We present the
“phase diagrams” in the two-dimensional space of texture
parameters, which suggests transitions between the wetting
states. We propose a model which allows the description of
transition states between (meta)stable contact states and
quantify the energy barriers between them. Thereby, we
theoretically suggest that the actually realized state is
not always the lowest energy state.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.