33 research outputs found
Polymer nano-doplets forming liquid bridges in chemically structured slit pores: A computer simulation
Using a coarse-grained bead-spring model of flexible polymer chains, the
structure of a polymeric nanodroplet adsorbed on a chemically decorated flat
wall is investigated by means of Molecular Dynamics simulation. We consider
sessile drops on a lyophilic (attractive for the monomers) region of circular
shape with radius R_D while the remaining part of the substrate is lyophobic.
The variation of the droplet shape, including its contact angle, with R_D is
studied, and the density profiles across these droplets also are obtained.
In addition, the interaction of droplets adsorbed on two walls forming a slit
pore with two lyophilic circular regions just opposite of one another is
investigated, paying attention to the formation of a liquid bridge between both
walls. A central result of our study is the measurement of the force between
the two substrate walls at varying wall separation as well as the kinetics of
droplet merging. Our results are compared to various phenomenological theories
developed for liquid droplets of mesoscopic rather than nanoscopic size.Comment: 8 pages, 9 figures, accepted in J. Chem. Phys. 200
Toward an experimental proof of superhydrophobicity enhanced by quantum fluctuations freezing on a broadband-absorber metamaterial
Previous theoretical works suggested that superhydrophobicity could be
enhanced through partial inhibition of the quantum vacuum modes at the surface
of a broadband-absorber metamaterial which acts in the extreme ultraviolet
frequency domain. This effect would then compete with the classical
Cassie-Baxter interpretation of superhydrophobicity. In this article, we first
theoretically establish the expected phenomenological features related to such
a kind of "quantum" superhydrophobicity. Then, relying on this theoretical
framework, we experimentally study patterned silicon surfaces on which
organosilane molecules were grafted, all the coated surfaces having similar
characteristic pattern sizes but different profiles. Some of these surfaces can
indeed freeze quantum photon modes while others cannot. While the latter ones
allow hydrophobicity, only the former ones allow for superhydrophobicity. We
believe these results lay the groundwork for further complete assessment of
superhydrophobicity induced by quantum fluctuations freezing.Comment: 10 pages, 5 figures, final version, accepted for publication in
Journal of Applied Physic
A review of wetting versus adsorption, complexions, and related phenomena: the rosetta stone of wetting
Caractère polyélectrolytique des interactions "ions diffusibles - polymères pariétaux" chez l'algue géante d'eau douce <i>Nitella flexilis</i> (L.) Ag.
Site-specific counterion binding and pectic chains conformational transitions in the <i>Nitella</i> cell wall.
Conformational transitions and modifications in ionic exchange properties induced by alkaline ions in the Nitella flexilis cell wall
Spreading on Heterogeneous Substrates
International audienceIn this article, we consider the wetting properties of surfaces coated by organic monolayers. These monolayers are either incomplete or chemically heterogeneous. Dynamics of relaxation of the advancing contact angle and high lateral resolution spectroscopic ellipsometry (HRSE) serve to characterize the surfaces and the spreading of branched hydrocarbon or of silicon oils droplets. Influence of the heterogeneity concentration on the friction coefficient (partial wetting regime) or on the pseudo diffusion coefficient (complete wetting regime) of the liquid molecules is presented. Comparisons are given with computer simulation results
Spreading on Heterogeneous Substrates
In this article, we consider the wetting properties of surfaces coated by organic monolayers. These monolayers are either incomplete or chemically heterogeneous. Dynamics of relaxation of the advancing contact angle and high lateral resolution spectroscopic ellipsometry (HRSE) serve to characterize the surfaces and the spreading of branched hydrocarbon or of silicon oils droplets. Influence of the heterogeneity concentration on the friction coefficient (partial wetting regime) or on the pseudo diffusion coefficient (complete wetting regime) of the liquid molecules is presented. Comparisons are given with computer simulation results