Green fabrication of pore-filling anion exchange membranes using R2R processing

Pore-filling ion exchange membranes are fabricated by complicated and energy-inefficient processes, use of large amounts of polar organic solvents, and optionally post-modification using acid or base. For green fabrication of pore-filling anion exchange membranes (PAEMs), we optimized the process parameters such as pretreatment time, impregnation time, water amount, and photo-polymerization rate of each step using roll to roll (R2R) equipment. Based on these optimized process parameters, a PAEM of 57.5 cm width and 39 μm thickness completely filled with a photo-cured electrolyte polymer was fabricated by aqueous pretreatment and by using an impregnation solution without toxic organic solvents. The impregnation step was conducted along with photo-polymerization at a line speed of 0.3 m/min without repeated impregnation with R2R equipment. The IEC, resistance, and permselectivity of this PAEM were similar to those of handmade PAEMs. The PAEM exhibited chemical stability in the pH range of 0–12. In addition, the reverse electrodialysis stack assembled with these PAEMs exhibited a higher power density than a stack of commercial ion exchange membranes. These results demonstrate that industrial-scale PAEM can be fabricated through a rapid, simple, environmentally friendly, and energy-efficient R2R process.