(161ar) A Hydrogen-Bonded, Super-Strong Two-Dimensional Polymer

Two-dimensional (2D) materials, regardless of their chemical compositions, feature covalent/ionic bonds within xy plane while weak van der Waals (vdW) interactions between 2D layers. For typical vdW 2D materials, stacking is generally highly ordered but fairly weak, resulting in a fragile mechanical nature. One nice example for illustration is that while graphene is considered as one of the strongest materials ever been discovered, its bulk form, graphite is rather brittle and has been used as a solid lubricant. Furthermore, due to their reversible stacking nature, controllable fabrication of vdW 2D material while retaining a perfect global orientation is rather difficult. Therefore, most thin “films” made from 2D materials are actually polycrystals, lacking of a long-range orientation across the whole plane. Herein, we report a chemically stable, highly processable non-vdW 2D polymer which has a rigid polyaramid framework in plane and strong interlayer hydrogen bonding along the third dimension. This 2D polymer dissolves easily in acid and forms homogenous, highly oriented films by simple drop-casting or spin-coating. Its 2D and well aligned nature were demonstrated by scanning force microscopy, polarized photoluminescence, and grazing-incidence wide-angle X-ray scattering. As a consequence of the strong hydrogen bonding and highly oriented stacking, excellent mechanical strength was observed and measured by both nanoindentation and macro-scale scrolled fiber tensile test.