The structure of a single flat electric double layer (EDL) is studied by grounding a symmetric electrolyte (NaCl), which is in contact with a planar positively corona-treated polypropylene film. Because the profiles of the electrostatic potential distribution and ion distribution in the solution are altered when the solution is grounded, some mobile counterions in the diffuse layer of the electrolyte solution will go into the Helmholtz layer and thus decrease the electric potential psi(a/2) at the Stern plane in order to obtain a new equilibrium. After the system is grounded for a long time, the representation of the electric double layer changes from a Stern model to a Helmholtz model. Theoretical and experimental analyses are given in this study. 相似文献
Summary: Single polyelectrolyte component microcapsules and multilayers, exemplified by poly(allylamine hydrochloride) (PAH), have been prepared using a method of glutaraldehyde (GA)‐mediated covalent layer‐by‐layer (LbL) assembly. The GA cross‐linking of the adsorbed PAH results in surfaces covered by reactive aldehyde groups, which can then react with PAH to result in another layer of covalently linked PAH. The repeated assembly of single polyelectrolyte in an LbL manner can be thus achieved. The PAH multilayers can grow linearly along with the layer number, and their thickness can be controlled at the nanometer scale, as verified by UV‐vis absorption spectrometry and ellipsometry. Single polyelectrolyte microcapsules are obtained after removal of the template cores at low pH. The morphology and integrity are confirmed by scanning force microscopy and confocal laser scanning microscopy.
Schematic illustration of the preparation of a single polyelectrolyte component microcapsule by GA‐mediated covalent LbL assembly. 相似文献
Poly(3,4-ethylenedioxythiophene (PEDOT) derivatives display a multitude of attractive properties such as high conductivity, biocompatibility, ease of functionalization, and high thermal stability. As a result, they show promise for applications in materials and biomedical engineering. In order to increase their applications in the practical domain, trivial fabrication techniques are required. Here, we present a simple layer-by-layer dip methodology to assemble water-soluble PEDOT derivatives that can then be disassembled via electrical stimulation. As a result, a dynamic PEDOT layered system is fabricated and could be applied as responsive materials for bioengineering. PEDOT-SO3 and PEDOT-NMe3 are synthesized via direct C-H arylation polymerization and chemical polymerization, respectively. The electrostatic interactions between oppositely charged SO3− and NMe3+ enabled the stacking of PEDOT derivatives. The layer-by-layer assemblies are confirmed by ultraviolet–visible spectroscopy and profilometer. Morphological analyses are performed using scanning electron microscopy and atomic force microscopy, which revealed that the polymer coatings are uniform without any cracks. In situ material assembly is studied using quartz crystal microbalance, and we also demonstrate that these PEDOT-derivative assemblies can be disintegrated by electrical stimulation. Cyclic voltammetry shows a proportional increase in stored charge density with the increase in bilayer thickness, confirming stable electroactivity of these assemblies. Using this approach, we can assemble conductive bio interface on both conductive and nonconductive surfaces, expanding the capability to fabricate bioelectronic electrodes. 相似文献
The effect of the number and arrangement of TiO2‐based photoanode layers on the efficiency of dye‐sensitized solar cells (DSSCs) was investigated. Compact, mesoporous, and blocking layers of TiO2 were prepared to form monolayer, bilayer, and trilayer photoanodes. Compact and blocking TiO2 layers were prepared using dip‐coating technique, whereas the doctor‐blade method was employed to prepare TiO2 paste layers using nanoparticles prepared by the sol–gel method. The crystalline structure of photoanodes was characterized by X‐ray diffraction (XRD) measurements and their morphology and thickness were characterized by the scanning electron microscopy (SEM) technique. The photovoltaic performance of constructed DSSC devices was investigated and the optimum arrangement was identified and explained in terms of dye loading enhancement and recombination reduction at the fluorine‐doped tin oxide (FTO)/electrolyte interface. 相似文献
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