Improving proton conductivity of SPES proton exchange membranes by incorporation of functionalized MOFs

Sulfonated polyethersulfone (SPES) has garnered extensive attention owing to its outstanding hydrolytic stability. However, the low proton conductivity of pristine SPES presents a challenge for its application in PEM. In this work, a series of composite membranes were fabricated by incorporating 1,3-propanesultone-modified UiO-66-NH 2 , which serves as a prospective filler in the polymer matrix. Comprehensive characterization of the composite membranes was conducted. The composite membrane containing 3 wt% S-UiO-66-NH 2 shows a tensile strength of 56.54 MPa and a proton conductivity of 169.3 mS/cm at 80 °C and 100% RH. Compared with the neat SPES membrane (42.26 MPa and 66.7 mS/cm under the same conditions), these values correspond to enhancements of 33.79% and 153.8%, respectively. The obvious elevation can be attributed to the abundant –COOH, –NH 2 , –SO 3 H groups in S-UiO-66-NH 2 and the hydrogen bonding involving –SO 3 H, which together provide abundant proton transport sites within the composite membrane. Meanwhile, hydrogen bonds not only provide proton transport channels but also establish a cross-linked proton transport network in the membrane. The improved structure reinforces interfacial adhesion between S-UiO-66-NH 2 and the polymer matrix, which contributes to enhanced mechanical properties. This study proposes a new strategy for developing high-performance proton exchange membranes, laying the foundation for the future application of SPES-based fuel cells.