Strong and flaw-insensitive two-dimensional covalent organic frameworks

Two-dimensional (2D) covalent organic frameworks (COFs) are promising polymeric crystalline nanomaterials with broad applications. However, the understanding of their mechanical properties and fracture mechanisms remains elusive. Here, we report a quantitative in situ tensile study of ultrathin COFTAPB-DHTA films. The fracture strength was measured to be 0.75 ± 0.34 GPa, and the tensile modulus was measured to be 10.38 ± 3.42 GPa, with a nominal...