Ion exchange bipolar membrane: poly(ether ether ketone) grafting poly(2-(N,N-dimethylaminoethyl) methacrylate) synthesized via ATRP

Poly(ether ether ketone) (PEEK) containing methyl groups was synthesized by the aromatic nucleophilic polycondensation reaction of 4, 4′-difluorobenzophenone, bisphenol-A and 2, 3,5-trimethylhydroquinone. Side-chain-type ion exchange membranes based on PEEK-g- P(DMAEMA) (poly(2-dimethylamino ethyl methacrylate)) were successfully synthesized via atom transfer radical polymerization (ATRP), using bromethylated poly(ether ether ketone) (BMPEEK) as the macroinitiator. These copolymers contain tertiary amino groups on their side chains with high molecular weight. The copolymer membranes exhibit excellent mechanical properties due to their aromatic backbone structure and flexible DMAEMA aliphatic chains. With the increase of grafting degree of DMAEMA, the ion exchange capacity (IEC) and water content of the membranes increase from 2.17 to 2.49 mmol · g⁻¹ and 67.22 to 90.97 %, respectively. The bipolar membranes originated from PEEK-g-P(DMAEMA) display reasonably high OH⁻ permeability and low AC impedance with high IEC.