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As considerable advance has recently been made in enhancing the conductivity of anion-exchange membranes, durability has become the critical requirement in the development of fuel cells. Such properties often develop at the expense of the other. In this work, new amphiphilic semi-interpenetrating networks composed of free polysulfone and crosslinked polysulfone are synthesized for the first time. The same nature of both polymers makes them highly compatible. The free polymer provides the hydrophobic component, whereas the crosslinked polysulfone, functionalized with trimethylammonium, 1-methylimidazolium, or 1,2-dimethylimidazolium groups, is responsible for the ionic conductivity. The compatibility between both components in the blend, improves the mechanical properties, while unaffecting the transport properties. Thus, the obtained membranes exceed the mechanical behaviour of commercial materials, even in conditions of extreme humidity and temperature. The tensile strength of these synthesized membranes can reach to relatively high values, and when compared to the commercial PSU, the difference in tensile strength can be noted to be as low as 10%. Moreover, the tensile strength and the ductility values of the crosslinked PSU are higher than those obtained with non-crosslinked PSU. Furthermore, the membranes presented in this work show a great alkaline stability (e.g. semi-interpenetrating network containing 1,2-dimethylimidazolium maintains 87% of the ionic conductivity after 14 days of treatment). Thus, these membranes provide an improvement in the durability limiting factors, in comparison to functionalized polysulfones, fulfilling the requirements to be used as electrolytes in anion-exchange membrane fuel cells. ; We thank Agencia Estatal de Investigación (AEI)/Fondo Europeo de Desarrollo Regional (FEDER/UE) for funding the project MINECO (MAT2016-78632-C4-3-R, and PID-2019-106662RB-C43) which supported this work. We also wish to thank the project from the Regional Government (Comunidad de Madrid through PEM4ENERGY-CM-UC3M).

This article belongs to the Special Issue Polymeric Membranes for Advanced Applications. ; In this work, anion exchange membranes based on polymer semi-interpenetrating networks were synthesized and characterized for the first time. The networks are composed of sulfonated polysulfone and 1-methylimidazolium-functionalized polysulfone crosslinked covalently with N,N,N′,N′-tetramethylethylenediamine (degree of crosslinking of 5%). In these membranes, sulfonic groups interact electrostatically with cationic groups to form an ionic crosslinking structure with improved alkaline stability. The effect of the ionic crosslinking on the thermal, chemical, mechanical, and electrochemical behavior of membranes was studied. These crosslinked membranes containing sulfonated polysulfone showed higher thermal stability, with a delay of around 20 °C in the onset decomposition temperature value of the functional groups than the crosslinked membranes containing free polysulfone. The tensile strength values were maintained above 44 MPa in all membranes with a degree of chloromethylation (DC) below 100%. The maximum ionic conductivity value is reached with the membrane with the highest degree of chloromethylation. The chemical stability in alkaline medium of the conducting membranes also improved. Thus, the ionic conductivity variation of the membranes after 96 h in a 1 M potassium hydroxide (KOH) solution is less pronounced when polysulfone is replaced by sulfonated polysulfone. So, the ionic crosslinking which joins both components of the blends together, improves the material's properties making progress in the development of new solid electrolyte for polymeric fuel cells. ; This work was funded by Agencia Estatal de Investigación (AEI)/Fondo Europeo de Desarrollo Regional (FEDER/UE), PID-2019-106662RB-C43, by the Spanish Government, MAT2016-78632-C4-3-R, and by the Regional Government PEM4ENERGY-CM-UC3M funded by the call "Programa de apoyo a la realización de proyectos interdisciplinares de I+D para jóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020" under the frame of the "Convenio Plurianual Comunidad de Madrid-Universidad Carlos III de Madrid".

This article also appears in: In Memoriam: Prof. Jean-Michel Savéant. ; In this report, the conductivity mechanism of Ca2+-ion in polyoxyethylene (POE) solid polymer electrolytes (SPEs) for calcium secondary batteries is investigated by broadband electrical spectroscopy studies. SPEs are obtained by dissolving into the POE hosting matrix three different calcium salts: CaTf2, Ca(TFSI)2 and CaI2. The investigation of the electric response of the synthetized SPEs reveals the presence in materials of two polarization phenomena and two dielectric relaxation events. It is demonstrated that the nature of the anion (i. e., steric hindrance, charge density and ability to act as coordination ligand) and the density of "dynamic crosslinks" of SPEs is fundamental in the establishment of ion-ion/ion-polymer interactions. The long-range charge migration processes occurring along the two revealed percolation pathways of the electrolytes are generally coupled with the polymer host dynamics and depend on the temperature and the anion nature. This study offers the needed tools for understanding Ca2+ conduction in POE-based electrolytes. ; This work has been supported by the European Union's Horizon 2020 research and innovation programme under grant agreement No 829145(FETOPEN-VIDICAT).V. Di Notothanks the University CarlosIII of Madrid for the "Catedras de Excelencia UC3M-Santander" (Chairof Excellence UC3M-Santander).