Development of Mixed Matrix Anion-Exchange Membranes from Chemically Modified Phenol-Formaldehyde Resin for Electrochemical Systems

Abstract

Anion exchange membranes (AEMs) play vital role in electrochemical applications. Conventional synthetic methods for AEMs are using reagents like chloromethyl methyl ether which is highly carcinogenic. Here, we are presenting a safe, simple, and cost-effective method for the fabrication of AEM. Phenol–formaldehyde prepolymer on condensation with guanidine was used as the anion exchange material and it was then dispersed in polyvinyl chloride (PVC) and membrane fabrication was done by solution casting method. This approach completely eliminates the usage of carcinogenic materials and enables uniform membrane fabrication.  This was confirmed by FT-IR spectroscopy. Thermogravimetric analysis (TGA) which showed thermal stability up to 150°C, which suggests that the membrane is appropriate for real-world applications. Scanning electron microscopy (SEM) showed an even and smooth surface of the membrane. AC impedance measurements demonstrated a significant increase in ionic conductivity with an increase in ion-exchange material content. The membrane exhibited an ionic conductivity of 65 mScm^-1at room temperature in 2M NaOH solution. The improved thermal stability, high ionic conductivity, and environmentally friendly synthesis make this method an interesting alternative to traditional AEM fabrication methods, which can have applications in energy storage and conversion devices.