High-performance anion exchange membranes based on semi-interpenetrating blends of polyethylene terephthalate and quaternized chitosan

High ionic conductivity and long-term durability of anion exchange membranes (AEMs) are indispensable to facilitate the commercial application of anion-exchange membrane fuel cells (AEMFCs). Herein, novel high performance AEMs are synthesized for the first time. Specifically, quaternized chitosan (QCS) with high ion content without chloromethylation is selected as the ion conduction phase, due to its low cost and biodegradability. Polyethylene terephthalate (PET) with high film-forming ability, excellent strength, dimensional stability, and physical properties is selected as the mechanical support material. Moreover, semi-interpenetrating polymer networks (s-IPNs) architecture is formed by cross-linking QCS with glutaraldehyde (GA) to enhance the compatibility and optimize the advantages of each polymer matrix. Consequently, the homogeneous semi-IPN AEMs combines the benefits of ionic network and rigid linear polymer, achieving high performance, surpassing the simple blend AEM. The PHM-4 exhibits excellent mechanical properties (24.5 MPa, 17.94 %), outstanding ionic conductivity (89.64 mS/cm, 80 °C), as well as excellent alkaline stability (91.5 % retaining of initial conductivity after immersing in 6 M NaOH at 80 °C for 500 h). Furthermore, the single fuel cell based on PHM-4 displays high performance of 305 mW/cm² (80 °C). This study proposes a new strategy for the synthesis of high-performance semi-IPN AEMs, further enhancing the application value of QCS based AEMs in fuel cells.