Evaluation of membrane preparation method on the performance of alkaline polymer electrolyte: Comparison between poly(vinyl alcohol)/chitosan blended membrane and poly(vinyl alcohol)/chitosan electrospun nanofiber composite membranes

The preparation and evaluation of two kinds of poly(vinyl alcohol)/chitosan polymer electrolyte membranes, PVA/CS solution casting membrane and PVA/CS composite electrospun nanofiber membranes, are reported in this study. The first PVA/CS membranes are prepared with solution casting method and crosslinked with glutaraldehyde solution. The second PVA/CS composite electrospun nanofiber membranes are prepared with electrospinning method and crosslinked with glutaraldehyde vapor and then dipped into the PVA/CS solution to get composite electrospun nanofiber membrane, CE-PVA/CS. The characterization of these membranes was studied with differential scanning calorimetry (DSC), thermogravimetry analysis (TGA). To evaluate the properties as alkaline polymer electrolyte membranes (APEMs), the various membranes were immersed in 40 wt% KOH solution to form the KOH containing polymer electrolyte membranes. The effect of chitosan (CS), crosslinking agent of glutaraldehyde (GA) and electrospinning method on the KOH uptake, ionic conductivity and methanol permeability of these membranes were also conducted. The ionic conductivity, methanol permeability, and selectivity for the PVA/CS solution casting alkaline polymer electrolyte membrane and composite electrospun nanofiber membrane (CE-PVA/CS) are at about (0.010 Scm⁻¹, 7.42 × 10⁻⁷ cm² s⁻¹, 13.5 × 10³ Scm⁻³s) and (0.010 Scm⁻¹, 2.28 × 10⁻⁷ cm² s⁻¹, 43.9 × 10³ Scm⁻³s), respectively. By comparing with the other studies for the different modified PVA membranes in published papers, our composite electrospun fiber membranes (CE-PVA/CS) has proper ionic conductivity, lower methanol permeability, and higher selectivity. It seems that our composite electrospun fiber membranes, CE-PVA/CS, is a good candidate for the alkaline solid polymer electrolyte membrane.