Facile fabrication of amphoteric semi-interpenetrating network ion-exchange membranes for electrodialysis applications

A series of amphoteric semi-interpenetrating polymer network ion-exchange membranes (AsIPN IEMs), composed of fluoro-methyl sulfonated poly(arylene ether ketone) (SPAEK) copolymer and in situ polymerized sulfobetaine acrylamide (SBMA), has been fabricated. In this work, the SPAEK serving as a linear polymer chain is expected to guarantee the ion conductivity and mechanical and dimensional stability, while polymerized SBMA with ion pairs can moderately narrow the ion channel reducing the anion transportation in AsIPN matrix via ionic cross-linkings. In particular, the thermogravimetric analysis demonstrates the presence of ionic cross-linking in AsIPN- X IEM matrix due to the degradation temperature of sulfonated groups shifting from ca. 350 to ca. 340 °C. In applications, electrodialysis (ED) with AsIPN-10 IEM shows the highest NaCl removal ratio of 89.6% within 110 min, outperforming 60 SPAEK (83.5%) commercial CEM-Type-II (86.1%). These demonstrate AsIPN-10 IEM has the potential in rendering ED of improved performance for separation application.