Fabrication of photocured anion-exchange membranes using water-soluble siloxane resins as cross-linking agents and their application in reverse electrodialysis

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>The utilization of large amounts of volatile organic solvents and the complicated process required for industrial manufacturing of ion-exchange membranes necessitate the development of simple, rapid, and environmentally friendly fabrication methods such as those based on photopolymerization. We employed hydrolytic sol–gel reactions between ammonium- and acrylamide-functionalized silane coupling agents to synthesize water-soluble siloxane resins that exhibit high condensation levels (>80%) and comprise oligomers with molecular weights below 2000 Da. These resins were then mixed with a hydrophilic monomer bearing ammonium and acrylamide groups, and porous polyethylene substrates were impregnated with the resulting mixtures and then irradiated with ultraviolet light. The hydrophilicity, mechanical strength, and other properties of the resulting membranes depended on the resin composition, indicating that the substrate pores were efficiently filled with the prepared resins and further suggesting that the membrane performance could be effectively altered by varying the resin composition. Moreover, the obtained membranes exhibited chemical stability in the pH range between 0 and 11 and in hot water at 60 °C. The reverse electrodialysis stack consisting of these membranes showed higher power density than a stack of commercial membranes. Therefore, it can be concluded that without employing volatile organic solvents for reverse electrodialysis, the developed technique is well-suited for the fabrication of ion-exchange membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Photocured anion-exchange membranes were fabricated using water-soluble siloxane resins. </LI> <LI> All resins had a high condensation degree, containing oligomers with <I>M</I> <SUB>w</SUB> < 2000 Da. </LI> <LI> These resins acted as cross-linkers and helped to avoid the use of organic solvents. </LI> <LI> The properties of the prepared anion-exchange membranes depended on resin composition. </LI> <LI> Reverse electrodialysis using the prepared membrane shows higher power density than that of the commercial membrane. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>