In this paper, we demonstrate that thin layers of polymer coatings can be used to self-assemble pillars into stable microstructures. Polymer coatings are deposited onto elastomeric pillars using solventless initiated chemical vapor deposition and capillary forces are used to collapse the coated pillars into microstructures. The location of pillar collapse can be controlled by patterning regions of hydrophilicity and hydrophobicity. Poly(hydroxyethyl methacrylate) and poly(methacrylic acid) coatings stabilize the self-assembled microstructures by providing an adhesive force through solvent bonding. These solvent bonds allow the response of the microstructures to be tuned by varying the thickness of the polymer coating and the solubility parameter of the solvent. The coating process described in this paper is substrate-independent and therefore can be applied to pillars composed of any material.
The overvoltage of the iron, nickel, and Raney Ni electrodes was measured in concentrated
normalNaOH
solutions under elevated temperatures. Experiments were conducted at 20 atm‐G to prevent water vaporization. With these results, the terminal voltages of the alkaline water electrolysis cell and the chlor‐alkali cell were evaluated to investigate the feasibility of high temperature operation. Iron was corroded seriously by hot concentrated caustic, and was found to be inadequate as the structural material under these conditions. Nickel was resistant to corrosion, but its overvoltage was high. The Raney Ni cathode exhibited very low hydrogen overvoltage characteristics for a short period and degraded irreversibly.
ChemInform Abstract are investigated for Fe, Ni, and Raney-Ni electrodes (50-200 rc C, 2-20 M NaOH, 2.1 MPa) in order to study the applicability of these materials as cathodes for alkaline water electrolysis cells and chlor-alkali cells. Iron is rapidly corroded by hot concentrated NaOH. Ni is resistant to corrosion, but its overvoltage is high. The Raney-Ni cathode exhibits low hydrogen overvoltage characteristics, but this material is irreversibly degraded at high temperature.
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