Effect of hydrophilic additive and PVC polymerization degree on morphology and electrochemical properties of PVC‐based heterogeneous cation‐exchange membrane

Abstract

Membrane solution composition is one of the important factors that determine properties of ion-exchange membranes. In this study, a PVC-based heterogeneous cation-exchange membranes were prepared by the solution casting method. Effects of a hydrophilic additive [poly(ethylene glycol), PEG400] and degree of polymerization of poly(vinyl chloride) (PVC) on the morphology and electrochemical properties of the cation-exchange membranes were investigated. The results revealed that the hydrophilic additive can improve membrane properties, including water uptake (Wu), ion-exchange capacity (IEC), conductivity, and permselectivity. The improvements might be associated with an increase in accessibility of functional sites in the membrane matrix due to a higher hydrophilicity, indicated by a reduction of water contact angle and the greater void fraction shown by scanning electron microscopy. However, the permselectivity slightly decreased when the additive concentration was increased further. Meanwhile, increasing the degree of polymerization and PVC concentration resulted in higher permselectivity and lower conductivity, which might be due to a better resin distribution and a lower void fraction. Overall, the prepared membranes had relatively good conductivities (up to 2.5 mS/cm) and permselectivities (up to 0.92). In general the conductivity increases with increased Wu and IEC, while the permselectivity showed the opposite trends. This could be associated with the efficacy of Donnan exclusion indicated by the IEC/Wu ratio and the Donnan equilibrium constant of the cation (K 1 ).

Poly(vinyl chloride)-Based Anion-Exchange Membrane with High-Antifouling Potential for Electrodialysis Application

“…Polymers, with hydrophilic or excellent film-forming performance, have been used to blend PVC to form a semi-interpenetration network. In the field of membrane materials, PVC was mainly used as a binder or a supporting material to prepare ultrafiltration membranes and heterogeneous ion-exchange membranes. , However, there are a few reports on the direct quaternization of PVC to prepare homogeneous AEMs, without the addition of any other functional materials (ion-exchange resin, binder, or supporting material). Usually, the as-prepared PVC membranes are used as sensors for battery separators or proton-exchange membranes (PEMs) for fuel cells. − For example, Hwang et al.…”