Esterification modification and characterization of polyvinyl alcohol anion exchange membrane for direct methanol fuel cell

A series of anion exchange membranes (AEMs) with high conductivity and stable chemical properties were prepared by using polyvinyl alcohol phytate (PPVA) as the polymer matrix, 1,4-diglycidyl butane ether (DGBE) as the crosslinking agent and 2,3-epoxypropyl trimethylammonium chloride (EPTMAC) as the quaternization reagent. The chemical structure of the AEMs synthesized in this paper was characterized by ATR-FTIR to determine the successful preparation of the membranes. Additionally, the mechanical property, OH − conductivity, alkaline stability, and single-cell performance of the membrane was also discussed. Based on our results, when the molar ratio of polyvinyl alcohol (PVA) to PA is 2:1, the content of DGBE is 10%, the maximum tensile strength (19.0 MPa) of the membrane was obtained, the anionic conductivity can reach up to 0.594 S·cm −1 and the power density reaches 122 mW·cm −2 at 80 °C. Moreover, the good alkali resistance stability of AEMs was also proved, which was due to the conductivity of the QPPVA 2 -DGBE 10% membrane can remain at around 80.7% of the initial conductivity when it was immersed in a 6 mol·L −1 KOH solution for 168 h at 60 °C. Compared with the commercial Nafion®-115 membrane, the prepared composite membranes synthesized in this paper have a lower methanol permeability in 3 mol·L −1 methanol at 60 °C, which is only 8.1% ~ 13.7% of Nafion®-115 membrane.