Mesoporous Metal-Organic Framework from Templated Synthesis as Mechanical Metamaterials

This work aims to demonstrate the fabrication of a mesoporous metal-organic framework (MOF) via templated synthesis using a self-assembled block copolymer as a template, giving a nanonetwork MOF with enhanced toughness due to the effect of deliberate structuring on mechanical performance (the character of mechanical metamaterials). Polystyrene-b-polydimethylsiloxane (PS-b-PDMS) can self-assemble as a diamond phase, followed by hydrofluoric acid etching of PDMS, giving mesoporous PS as a template for the coordination-driven self-assembly reaction of ZIF-67. After the templated synthesis of ZIF-67, followed by removal of the PS template, diamond-structured mesoporous ZIF-67 with faceted texture can be obtained due to the confined growth of ZIF-67 as a single crystal. The deliberate structuring with the nanonetwork struts of the mesoporous ZIF-67 single crystal gives a significant improvement in energy dissipation capability with a brittle-to-ductile transition, as evidenced by nanoindentation tests, offering promising catalytic applications by improving the accessible active sites in mesoporous MOF and material toughness due to the nanonetwork structure.