Construction of alkaline-stable bacterial-cellulose-based anion exchange membranes by radiation-induced in-situ graft polymerization

Abstract

Preparing high-performance anion exchange membranes (AEMs) with dimensional stability and long-term durability is challenging. Here, a series of functional filler-modified bacterial cellulose (BC)-based AEMs was fabricated by infiltrating a cationic monomer (vinylbenzyl trimethylammonium chloride, VBTAC) into polydopamine-coated BC (PDA@BC), followed by ultraviolet (UV)-induced polymerization. The resulting membranes, denoted as BC/PDVD, exhibited superior alkali stability and hydroxide ion conductivity. The highest water uptake and area swelling of BC/PDVD were 1138.82% and 36.05%, respectively. The hydroxide conductivity of the BC/PDVD membranes ranged from 78.49 to 82.78 mS cm⁻¹ at 80 °C. Moreover, the in situ polymerization of the ionic filling polymer and its effective cross-linking with BC nanofiber network significantly enhanced the compatibility and alkali resistance of the composite membranes. After immersion in a 1 M KOH solution at 60 °C for 1500 h, BC/PDVD_10% maintained 91.86% of its initial conductivity. This UV radiation-induced in-situ graft polymerization and pore-filling strategy provides a reliable approach to reduce the “trade-off” between mechanical stability and electrochemical characteristic of AEMs.