Search results for "Wetting"

Simulation of liquid penetration in paper

2006

Capillary penetration of a wetting liquid in a microtomographic image of paper board, whose linear dimension was close to the average length of wood fibers, was simulated by the lattice-Boltzmann method. In spite of the size of the system not being large with respect to the size of structural inhomogeneities in the sample, for unidirectional penetration the simulated behavior was described well by that of the Lucas-Washburn equation, while for radial penetration a radial capillary equation described the behavior. In both cases the average penetration depth of the liquid front as a function of time followed a power law over many orders of magnitude. Capillary penetration of small droplets of…

Reactive Coatings in Glass Capillaries: Preparation of Temperature- and Light-Responsive Surfaces and Accurate Determination of Wettability Switching

2015

Plasmonic nanostructures for light trapping in thin-film solar cells

2019

Abstract The optical properties of localized surface plasmon resonances (LSPR) sustained by self-assembled silver nanoparticles are of great interest for enhancing light trapping in thin film photovoltaics. First, we report on a systematic investigation of the structural and the optical properties of silver nanostructures fabricated by a solid-state dewetting process on various substrates. Our study allows to identify fabrication conditions in which circular, uniformly spaced nanoparticles are obtainable. The optimized NPs are then integrated into plasmonic back reflector (PBR) structures. Second, we demonstrate a novel procedure, involving a combination of opto-electronic spectroscopic tec…

Capillary condensation in the two-dimensional lattice gas: A Monte Carlo test of fluctuation corrections to the Kelvin equation

1997

A two-dimensional lattice gas model with nearest-neighbour attractive interaction confined in a strip of width L between two parallel boundaries at which an attractive short-range force acts is studied by Monte Carlo simulations, for cases where the system is in the wet phase near the critical wetting transition line for . We study the shift of the chemical potential of the transition in the strip as a function of L by thermodynamic integration methods, , and also obtain the thickness of the wetting film at the chemical potential at which capillary condensation occurs. In the range the data are consistent with a variation according to the Kelvin equation, , as well as with a shifted Kelvin …

Probing predictions due to the nonlocal interface Hamiltonian: Monte Carlo simulations of interfacial fluctuations in Ising films

2019

Extensive Monte Carlo simulations have been performed on an Ising ferromagnet under conditions that would lead to complete wetting in a semi-infinite system. We studied an L×L×D slab geometry with oppositely directed surface fields so that a single interface is formed and can undergo a localization-delocalization transition. Under the chosen conditions the interface position is, on average, in the middle of the slab, and its fluctuations allow a sensitive test of predictions that the effective interactions between the interface and the confining surfaces are nonlocal. The decay of distance dependent correlation functions are measured within the surface, in the middle of the slab, and betwee…

Isotropic-nematic interface and wetting in suspensions of colloidal platelets.

2006

We study interfacial phenomena in a colloidal dispersion of sterically stabilized gibbsite platelets, exhibiting coexisting isotropic and nematic phases separated by a sharp horizontal interface. The nematic phase wets a vertical glass wall and polarized light micrographs reveal homeotropic surface anchoring both at the free isotropic-nematic interface and at the wall. On the basis of complete wetting of the wall by the nematic phase, as found in our density functional calculations and computer simulations, we analyze the balance between Frank elasticity and surface anchoring near the contact line. Because of weak surface anchoring, the director field in the capillary rise region is uniform…

Ionic liquid modified zinc oxide injection layer for inverted organic light-emitting diodes

2013

Abstract We have demonstrated a novel approach for fabricating efficient hybrid organic–inorganic light emitting diodes (HyLEDs) by introducing dopants into solutions processable metal oxides as an interfacial layer. The doped ZnO is prepared by adding ionic liquid (IL) to a precursor solution for the ZnO. In this way a heavily doped ZnO:ILs cathode was obtained that enhances the electron injection properties and assures a good wetting of the organic active materials.

Nanodroplets on a solid plane: wetting and spreading in a Monte Carlo simulation

2002

Abstract The wetting behavior and spreading dynamics of small polymer melt droplets in the course of transition from partial to complete wetting conditions on a flat structureless solid substrate have been studied by dynamic Monte Carlo simulation. From the density profiles of the drops we determine the contact angles at varying strength of the van der Waals surface forces in the whole interval of partial wetting. The validity of Young's equation is then tested whereby the surface tension of the melt/vapor interface is derived independently from interfacial fluctuation analysis, and the surface free energy of the melt at the substrate—from the anisotropy of the local pressure at the wall. T…

Curvature as a Guiding Field for Patterns in Thin Block Copolymer Films

2018

Experimental data on thin films of cylinder-forming block copolymers (BC)—free-standing BCmembranes as well as supported BC films—strongly suggest that the local orientation of the BC patternsis coupled to the geometry in which the patterns are embedded. We analyze this phenomenon using generalsymmetry considerations and numerical self-consistent field studies of curved BC films in cylindricalgeometry. The stability of the films against curvature-induced dewetting is also analyzed. In goodagreement with experiments, we find that the BC cylinders tend to align along the direction of curvature athigh curvatures. At low curvatures, we identify a transition from perpendicular to parallel alignm…

Surface effects on kinetics of ordering

1992

We study the effects of surfaces on the kinetics of phase changes in Ising-type systems. If the surface effects can be modelled by a field which couples linearly to the local order parameter, the growth of wetting or drying layers occurs. The numerical solution of the corresponding time-dependent Ginzburg-Landau equation yields a temporally logarithmic growth for the thickness of a wetting (drying) layer growing from an unstable dry (wet) state. On the other hand, if one starts off with a metastable state, the radius of a supercritical plug (wet or dry) grows linearly in time, in accordance with recent experimental results.