Enhancement of hydroxide conductivity by incorporating nanofiber-like palygorskite into quaternized polysulfone as anion exchange membranes

The natural hydrophilic nanofiber-like palygorskite (Pal) particles were incorporated into the quaternary ammonium functionalized polysulfone (QPSf) to prepare high performance anion exchange membranes . Due to the mutual compatibility between quaternary ammonium groups in quaternized polysulfone and hydrophilic Pal particles, a hydrophilic domain could aggregate, thereby forming a hydrophilic-hydrophobic microphase separation structure. Meanwhile, the small-angle X-ray scattering (SAXS) was utilized to characterize the hydrophilic ionic cluster domain in the composite membrane. The results showed that the corresponding average inter-domain spacing of the QPSf/Pal-0.5 membrane was about 30 nm. Then, the new composite membrane had not only highly efficient hydrophilic ion transport channels but also adjustable hydrophilic-hydrophobic microphase separation structures. Compared with original quaternized polysulfone membranes, the hydroxide conductivity of the QPSf/Pal-0.5 membrane reached 93.0 mS·cm −1 at 80 °C, increasing by 48%, while the methanol permeability was kept between 4.2 × 10 −7 and 5.8 × 10 −7  cm 2 ·s −1 .