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 degrees 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 degrees C. Compared with the commercial Nafion (R)-115 membrane, the prepared composite membranes synthesized in this paper have a lower methanol permeability in 3 mol.L-1 methanol at 60 degrees C, which is only 8.1%similar to 13.7% of Nafion (R)-115 membrane.

Automated summary

In this study, anion exchange membranes (AEMs) with high conductivity and stable chemical properties were prepared 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 AEMs showed excellent mechanical property, OH- conductivity, alkaline stability, and single-cell performance. The optimal conditions for membrane preparation were determined based on the molar ratio of polyvinyl alcohol (PVA) to PA, the content of DGBE, resulting in a membrane with high tensile strength, high anionic conductivity, and good alkali resistance stability.