Functionalized Boron Nitride Nanosheets: A Thermally Rearranged Polymer Nanocomposite Membrane for Hydrogen Separation

Amino functionalized boron nitride nanosheets (FBN) were incorporated into a crosslinked, thermally rearranged polyimide (XTR) to fabricate FBN‐XTR nanocomposite membrane. The FBN‐XTR membrane exhibited a small decrease in H2 permeability but demonstrated a remarkably increased H2 gas selectivity over other gases, compared with XTR. The XTR membrane heat‐treated at 425 °C had a H2 permeability of 210 Barrers and a H2/CH4 separation factor of 24.1, whereas the nanocomposite membrane with 1 wt % FBN exhibited a H2 permeability of 110 Barrers and H2/CH4 separation factor of 275, an order of magnitude greater. At 1 wt % FBN loading, the FBN‐XTR membrane showed three times higher tensile strength and 60 % higher elongation than pristine XTR membrane. In addition, FBN‐XTR was found to be able to be readily processed into thin‐film membranes for practical H2 separation applications. Large improvement in hydrogen selectivity and mechanical properties of thermally rearranged polymer membranes is achieved by incorporating functionalized boron nitride nanosheets. The thin‐film nanocomposite membrane can be readily fabricated to achieve ultrahigh hydrogen flux, showing great potential for practical hydrogen separation.