Enhanced Proton Conductivity of a Sulfonated Polyether Sulfone Octyl Sulfonamide Membrane via the Incorporation of Protonated Montmorillonite

Hybrid membranes consisting of sulfonated poly (ether sulfone) octyl sulfonamide (SPESOS) cast together with protonated montmorillonite (H-MMT, 1, 3, and 6 wt%) were fabricated and characterized. Fourier-transform infrared (FT-IR) spectra of the H-MMT/SPESOS composites confirmed that no chemical reactions occurred between the SPESOS and clay. X-ray diffractograms (XRD) showed a significant shift in the major peak of SPESOS at 2 theta = 15.5 degrees due to the incorporation of H-MMT. Furthermore, scanning electron microscopy (SEM) confirmed a homogeneous structure of the composite, and thermogravimetric analysis (TGA) results revealed that the addition of H-MMT promoted water absorption via the decrease in the loss of composite mass during evaporation. The SPESOS with H-MMT had higher water retention, contact angle, and proton conductivity values than pristine SPESOS. The proton conductivity of the hybrid membranes, however, improved at 100 degrees C from 42 mS/cm in pure SPESOS to 787, 350, and 300 mS/cm for the 1, 3, and 6 wt% H-MMT hybrids, respectively. These results demonstrate that the incorporation of the H-MMT is a viable strategy to boost the performance of SPESOS to construct a possible membrane for applying in fuel cells.