posted on 2024-01-19, 16:38authored byLingyu Yang, Chengkai Fan, Haifeng Gao, Jennifer L. Schaefer
Microphase
separation is a successful method for forming polymer
membranes with simultaneous high ionic conductivity and dimensional
stability. In this study, we developed a new strategy for designing
anion exchange membranes (AEMs) with inherent microphase separation
and improved alkaline stability via Friedel–Crafts (F–C)
hydroxyalkylation polycondensation. We achieved stable microphase
separation in the membrane when multisegmented block copolymers (MSBCPs)
synthesized from the F–C hydroxyalkylation reaction were used
for casting films. The formation of MSBCPs and microphase separation
were confirmed by proton nuclear magnetic resonance spectroscopy and
small-angle X-ray scattering spectroscopy, respectively. In comparison
to F–C random copolymers, the F–C MSBCPs with the same
ion-exchange capacity showed higher hydroxide conductivity (67 mS/cm
at 80 °C) with lower water uptake and swelling degree. This membrane
retained 52% of the fresh ionic conductivity and maintained microphase
segregation after being soaked in a 1 M KOH aqueous solution at 80
°C for 28 days. This synthetic method offers a new pathway for
producing AEMs with structure control and stable ion channels.