Adamantane-based block poly(arylene ether sulfone)s as anion exchange membranes

Current anion exchange membranes (AEMs) for fuel cells suffer from low ionic conductivity and poor mechanical property. Herein, we introduce adamantane groups onto the block poly(arylene ether sulfone)s backbone to form the selected comb-shaped structure. The structure-property relationships of the AEMs are investigated by varying the ratio of the hydrophobic to hydrophilic segments. The bulk rigid adamantane group can restrain the swelling of the AEMs thus enhancing the mechanical properties and expand the spacing between the hydrophilic/hydrophobic segments of the polymer chains to promote the formation of microphase separation morphology. Consequently, as characterized by atomic force microscope (AFM) and transmission electron microscopy (TEM), the resulting membranes show well-defined microphase separation between the hydrophilic/hydrophobic segments, resulting in high ionic conductivity range from 27.4 to 90.2 mS cm−1 over a temperature range of 30–80 °C. At the same time, the membranes present ultralow swelling ratio with the levels from 1.6% to 6.1% at 30 °C and from 6.8% to 12.7% at 80 °C, respectively, and thus excellent mechanical properties with the tensile strength as high as 11.52 MPa and elongation at break of 29.28%. The excellent comprehensive properties grant the prepared AEMs bright future for fuel cells.