Self‐Assembly of Metal–Organic Frameworks into Monolithic Materials with Highly Controlled Trimodal Pore Structures

We present a two‐step template‐free approach toward monolithic materials with controlled trimodal porous structures with macro‐, meso‐, and micropores. Our method relies on two ordering processes in discrete length scales: 1) Spontaneous formation of macroporous structures in monolithic materials by the sol–gel process through the short‐range ordered self‐assembly of metal–organic frameworks (MOFs), and 2) reorganization of the framework structures in a mediator solution. The Zr‐terephthalate‐based MOF (UiO‐66‐NH₂) was adopted as a proof of concept. The self‐assembly‐induced phase separation process offered interconnected macropores with diameters ranging from 0.9 to 1.8 μm. The subsequent reorganization process converted the microporous structure from low crystalline framework to crystalline UiO‐66. The resultant mesopore size within the skeletons was controlled in the range from 9 to 21 nm. This approach provides a novel way of designing spaces from nano‐ to micrometer scale in network‐forming materials.