Synthesis and characterization of cross-linked quaternized chitosan/poly(diallyldimethylammonium chloride) blend anion-exchange membranes

Abstract

Novel alkaline anion-exchange membranes composed of quaternized chitosan and poly(diallyldimethylammonium chloride) were prepared by a combined thermal and chemical cross-linking technique. The hydroxide conductivity (σ), water uptake (WU), ion exchange capacity (IEC), thermal stability, mechanical property, alkaline stability of HTCC/PDDA-OH− membranes were measured to evaluate their applicability in alkaline fuel cells. FTIR, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were also used to investigate the relation between the inner structure and performance of the blend membranes. The HTCC/PDDA-OH− membranes show a high OH− conductivity up to 37.9 mS cm−1 at 80 °C (1:0.5 by mass). By cross-linking modification, the membranes exhibit excellent thermal stability with onset degradation temperature above 200 °C and good alkaline resistance in 8M KOH solution at 80 °C, decreasing slightly for hydroxide conductivity during 350 h. Meanwhile, the membranes show outstanding mechanical properties, the maximum tensile strength can reach 25.31 MPa and elongation at break is 6.58%.