Polymer electrolytes are attractive for the applications in conventional electrochemical devices and emerging flexible devices. In this study, we developed a poly(urethane acrylate)‐based gel polymer electrolyte with excellent mechanical stability, optical transparency, and a high ionic conductivity. These polymer electrolytes showed excellent dimensional stability and an elastomer‐like behavior with a Shore A hardness in the range of 20–40. The optical transmittance values of these polymers films were over 80% in the visible range. Their ionic conductivities were controlled via changes in the concentration of the linker, dimethylol propionic acid (DMPA), and the lithium salt incorporated into the polymer. The maximum ionic conductivity reached 3.7 mS/cm at room temperature (∼23 °C) when the DMPA/poly(ethylene glycol) molar ratio was 0.25, and the ionic conductivity was found to be proportional to the salt concentration. We believe that these polymer electrolytes will be useful in various electrochemical applications where flexibility, high ionic conductivity, and transparency in the electrolytes are necessary. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45009.

High-performance devices based on conducting polymers (CPs) require the fabrication of a thick CP-coated electrode with high stability. Herein, we propose a method for enhancing the interfacial adhesion strength between a gold electrode and an electropolymerized polypyrrole (pPy) layer by introducing a polyethyleneimine (PEI) layer. Although this insulating layer hinders the initial growth of the pPy layer on the Au surface, it improves the adhesion by up to 250%. Therefore, a thick layer of pPy can be fabricated without delamination during drying. X-ray photoelectron spectroscopy shows that the PEI layer interacts with the Au surface via polar/ionic groups and van der Waals interactions. Scanning electron microscopy reveals that the cohesion of the pPy layer is stronger than the interfacial adhesion between the PEI layer and the pPy layer. Importantly, the electroactivities of pPy and its dopant are unaffected by the PEI layer, and the electrochemical storage capacity of the pPy layers on the PEI-coated Au electrodes increases with thickness, reaching ~530 mC/cm2. Negative potential sweep is detrimental to pPy layer adhesion: pPy layers on a bare Au electrode peel off instantly as the potential is swept from 0.2 to −0.7 V, and most of the charge stored in the layer becomes inaccessible. In contrast, pPy layers deposited on PEI coated Au electrode are mechanically stable and majority of the charge can be accessed, demonstrating that this method is also effective for enhancing electrochemical stability. Our simple approach can find utility in various applications involving CP-coated electrodes, where thickness-dependent performance must be improved without loss of stability.

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High ionic conductivity and good stability are major factors that influence the use of polymer electrolytes in electrochemical storage and conversion devices. In this study, we present polyurethane acrylate (PUA) membranes having enhanced ionic conductivity and swelling stability by double crosslinking the polyurethane (PU) and polyacrylate (PA) compartments. The crosslinking agent concentration was varied to control their mechanical properties, swelling stability, and ionic conductivity. Under optimum conditions, the electrolyte uptake of the double-crosslinked PUA membranes without notable defects was 245%. The maximum ionic conductivity of these membranes reached 9.6 mS/cm, which was higher than those with respect to most of the previously reported PUA- or PU-based polymer electrolytes.

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