This paper discusses a new class of high performance polyethylene-based anion exchange membranes (PE–AEMs) that contain a wide concentration range of pendant (flexible) ammonium chloride (NR3 +Cl–) groups and with or without a cross-linked PE matrix structure. The chemistry involves a metallocene-mediated polymerization of ethylene, silane-protected α,ω-amino-olefin [C x N(SiMe3)2], with or without styrenic diene (cross-linker), to form ethylene/C x N(SiMe3)2 copolymers and ethylene/C x N(SiMe3)2/diene terpolymers, respectively. The resulting co- and ter-polymers were completely soluble in common organic solvents and were solution-casted into uniform films (thickness, 50–70 μm; without backing material) and then thermal cross-linked in ethylene/C x N(SiMe3)2/diene case, further interconverting the silane-protected amino groups into the desired −NR3 +Cl– groups (R: H, CH3, and C3H7) under solid state conditions. The resulting PE–NR3 +Cl– and cross-linked x-PE–N(CH3)3 +Cl– membranes were systematically studied to understand how the PE structure (−NR3 +Cl– concentration, R group, cross-linking density, etc.) affects ionic conductivity, water uptake, film stability, and ion selectivity. For comparison, several commercially available AEMs were also examined. Evidently, an x-PE–N(CH3)3 +Cl– membrane, with 28.1 mol % −N(CH3)3 +Cl– groups and 0.2 mol % cross-linkers, shows moderate water swelling and outperforms all commercial membranes with exceptionally high ionic conductivities of 119.6 mS/cm in 2 N HCl solution and 78.8 mS/cm in 2 N HCl–0.2N CuCl solution at room temperature.

This paper discusses a new class of proton exchange membranes (PEMs) that are based on a wellcontrolled polyolefin graft copolymer containing a polyethylene (PE) backbone and several sulfonated poly(arylene ether sulfone) (s-PAES) side chains. The chemistry involves a graft-onto reaction between high molecular weight PE with few pendent benzyl bromide groups and poly(arylene ether sulfone) (PAES) with two terminal phenol groups. The resulting PE-g-PAES graft copolymer, with predetermined backbone molecular weight, graft density, and graft length, was solution-cast into uniform film (thickness 20−40 μm), followed by a heterogeneous sulfonation reaction of PAES side chains to obtain the desired PE-g-s-PAES PEMs with a high sulfonation level. The unique combination of hydrophobicity, semicrystallinity, and high molecular weight of the PE backbone offers PEM with a stable (nonswellable) matrix. The embedded hydrophilic s-PAES proton-conductive domains show only moderate water uptake, even with a high ion exchange capacity (IEC >3 mmol/g in the s-PAES domains). Compared to Nafion 117, most PE-g-s-PAES PEMs show similar hydration numbers (λ <15) but higher proton conductivity (up to 160 mS/cm). More interestingly, all PE-g-s-PAES PEMs show higher through-plane conductivity than in-plane conductivity. Evidently, a thin hydrophobic PE layer is formed on the PEM surfaces due to the low surface energy of PE, resulting in anisotropic conductivity. Overall, this newly developed PE-g-s-PAES membrane offers a combination of desirable properties, including conductivity, water uptake, mechanical strength, and cost-effectiveness for fuel cell applications.

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Bacterial vaginosis is a common female disease caused by a vaginal infection due to an overgrowth of bacteria that naturally live in the vaginal tract. Bacterial vaginosis has frequently been treated with the oral or vaginal administration of antibiotics and topical disinfectants. However, hygienic application of topical treatment deep in the vagina remains difficult. Herein, we introduce a novel vaginal cleaning device using plasma-activated water generated from supplied water. Remarkably, plasma source generation at atmospheric pressure is well known to eradicate bacterial infection through the generation of free radicals and/or chlorine chemicals with antimicrobial activity. The device was designed to alleviate a bacterial infection by spraying plasma-activated water generated from a cleaning solution container with plasma modules. The spray nozzle contains both a clean outlet and a suction outlet to spray and recover the plasma water, respectively, and is connected to a disposable silicone tube. The other nozzle, which has a laser light and air pump, can perform a second sterilization and dry the vagina after washing. Free chlorine chemicals with antibacterial activity were detected in the plasma-activated water by the device. Clinical application in patients with bacterial vaginosis confirmed the stability and effectiveness of our device. Therefore, these results show a novel clinical application of atmospheric pressure plasma to medical field as a plasma medicine.

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This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young’s modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO2• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

In order to evaluate the effects of a variation of a supporting springs' shape on the wear behavior of a nuclear fuel rod, sliding wear tests have been performed in room temperature air and water. The objective of the tests is to quantitatively evaluate the relationship between a worn area and a wear volume, and the formation behavior of a worn area with a variation of the slip amplitudes, applied normal loads and supporting spring shapes. The results indicated that the variation behavior of the volume and the wear scar size was influenced by the contact shape between the springs and the fuel rods. Also, it was found to be possible to evaluate a critical ratio (Tc) for each spring shape and test condition when the T was defined as the ratio of an applied normal load (Ln) to a wear scar size (At). Below this Tc, the wear volume was rapidly increased and the Tc was determined by a variation of the At under the same applied normal load condition. This result enables us to evaluate a wear resistant spring shape by using an analysis of a wear scar after wear tests have been completed. Based on the above results, the relationship between At and a worn area (Aw), a wear mechanism and an evaluation method for a wear resistance were discussed.

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