Interpenetrating anion exchange membranes using poly(1-vinylimidazole) as bifunctional crosslinker for fuel cells

• Interpenetrating AEMs were developed using a bifunctional crosslinker.
• PVBC-c-PVIm leads simultaneously to high conductivity and low swelling.
• The AEMs display excellent thermal, chemical and dimensional stability.

There is a balance between ionic conductivity and dimensional stability in anion exchange membranes (AEMs). High conductivity resulting from densely charged groups is normally accompanied with high water uptake and excessive swelling. Herein, a series of novel AEMs with interpenetrating network was prepared by the incorporation of poly(vinylbenzyl chloride) (PVBC) and poly(1-vinylimidazole)(PVIm) into the PVA matrix. PVBC and PVIm act as bifunctional macromolecular crosslinking agents to provide both imidazolium cations and to form crosslinked network in the membranes. The resulting AEMs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effect of crosslinking density on conductivity, water uptake, swelling ratio and stability was investigated. The results reveal that the addition of PVBC-c-PVIm could be simultaneously conducive to higher conductivity and lower swelling ratio. Notably, the membrane containing 50 wt% PVBC-c-PVIm had IEC of 1.86 meq g−1, water uptake of 39.4%, and hydroxide conductivity of 21.9 mS cm−1 at 30 °C. A maximum power density of 37.1 mW cm−2 is achieved at a current density of 64 mA cm−2. The crosslinked AEMs also exhibit excellent alkaline stability in a 4 M KOH solution at 60 °C for 1320 h.