Development of polyvinyl alcohol/chitosan blend anion exchange membrane with mono and di quaternizing agents for application in alkaline polymer electrolyte fuel cells

Abstract

Anion exchange membranes (AEM) functionalized by quaternary ammonium moiety are fabricated from polyvinyl alcohol/chitosan blend. Polymers namely polyvinyl alcohol (PVA) & chitosan (CS) are quaternized individually and mixed together to form blend solution, further cross-linked chemically and cast to form QPVA/QCS membrane followed by thermal treatment. Two types of membranes were prepared via, Quaternization of PVA and CS using alkyl spacers (mono quaternizing agent) and Quaternization of PVA and CS using dual reagents, of varying wt %. Further, these membranes are cross-linked by chemical and thermal methods prior to ionic conductivity and ion exchange capacity evaluation. The reaction of quaternizing groups with PVA/CS backbone is interpreted using FTIR spectroscopy. The QPVA/QCS membrane with 20 wt% of alkyl spacer exhibits enhanced conductivity of 0.0047 S cm−1 at 40 °C in comparison with all other ratios. Also, the alkaline stability of the optimized QPVA/QCS membrane evaluated till 300 h shows an enhanced stability with lesser conductivity loss. Keywords: Anion exchange membrane, Polyvinyl alcohol, Chitosan, Blend membrane, Morphology