Nikolaus Knorr*, Silvia Rosselli and Gabriele Nelles,
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引用次数: 0
Abstract
Water dewetting generates static electricity. We reviewed historical experiments of this phenomenon, and we studied the charging of polymer slides and metal electrode supported polymer films withdrawn vertically from a pool of aqueous solutions. For pure water, charging was negative and surface charge densities increased with the speed of dewetting, which we explain by the thermally activated entrainment of nanometer-sized water droplets or clusters charged by unbalanced adsorbed electric double-layer ions. Surface charge densities increased for reduced polymer film thickness following a power law, which we explain by reduced discharge of the entrained water volumes. At low salinity c ≲ 10 μM, charging was proportional to electrokinetic interfacial charge densities: the negative charging was increased for alkaline solutions and for most salts at μM concentrations and the charge polarity was inversed to positive for a cationic surfactant, a salt with a highly positively charged cation, and for a strong acid at approximately pH 4. Charging was reduced again for c ≳ 100 μM, especially at high dewetting speeds and for chaotropic ions, which we explain by the entrainment of larger and more discharged droplets. We determined adsorption energies of the charged water clusters on the dewetted surface from thermally stimulated discharge of the charged polymer slides and we show that the surface charge distribution, imaged by charged toner powders and measured microscopically by Kelvin probe force microscopy, is a record of the dewetting process that provides spatial and kinetic information about the three-phase contact line motion.
期刊介绍:
Langmuir is an interdisciplinary journal publishing articles in the following subject categories:
Colloids: surfactants and self-assembly, dispersions, emulsions, foams
Interfaces: adsorption, reactions, films, forces
Biological Interfaces: biocolloids, biomolecular and biomimetic materials
Materials: nano- and mesostructured materials, polymers, gels, liquid crystals
Electrochemistry: interfacial charge transfer, charge transport, electrocatalysis, electrokinetic phenomena, bioelectrochemistry
Devices and Applications: sensors, fluidics, patterning, catalysis, photonic crystals
However, when high-impact, original work is submitted that does not fit within the above categories, decisions to accept or decline such papers will be based on one criteria: What Would Irving Do?
Langmuir ranks #2 in citations out of 136 journals in the category of Physical Chemistry with 113,157 total citations. The journal received an Impact Factor of 4.384*.
This journal is also indexed in the categories of Materials Science (ranked #1) and Multidisciplinary Chemistry (ranked #5).