Chitosan–poly(vinyl pyrrolidone) blends as membranes for direct methanol fuel cell applications

Blend membranes made of chitosan (CS) and poly(vinyl pyrrolidone) (PVP), were synthesized and characterized for their ion exchange capacity (IEC) and Swelling Index to investigate their applicability in direct methanol fuel cells (DMFC). These membranes were assessed for their intermolecular interactions and thermal stability using FT-IR, X-ray diffraction methods, and TGA. Their methanol permeability and proton conductivity were also estimated and compared to that of Nafion 117. In addition to being effective methanol barriers, the membranes have a high ion exchange capacity (IEC) and possess adequate thermal stability. Crosslinking the polymer blend using glutaraldehyde and sulfuric acid has been particularly effective in producing a reduction of methanol permeability from 9.2 × 10−8 cm2 s−1 for CS/PVP blend to 7.3 × 10−8 cm2 s−1 for crosslinked CS/PVP blend (GS-CS/PVP) and enhancing the conductivity from 0.019 S cm−1 for CS/PVP blend to 0.024 S cm−1 for GS-CS/PVP, thereby rendering it more suitable for a DMFC. Low methanol permeability, excellent physico-mechanical properties and above all, the cost effectiveness could make their use in DMFC quite attractive.