Micro/Nano-Scaled Covalent Organic Frameworks: Polymerization, Crystallization and Self-Assembly

In the past decade, considerable efforts have been extended on covalent organic frameworks (COFs), however, the basic research about the nucleation and crystal growth of COF materials has been greatly ignored. This review aims at providing an overview over the theoretical foundation and experimental observation of the multi-scale structural engineering of COF materials, which includes complex polymerization, crystallization and self-assembly processes. In this perspective, we first highlighted the latest advances on basic knowledge about the nucleation and growth of COFs, including classical and non-classical crystallization mechanism as well as the synthesis of COF single crystals. Subsequently, we surveyed the effects of synthesis conditions, such as catalysts, monomer adding modes, heating methods, modulator and supramolecular interaction on the formation of COF materials. In the last, the research on the synthesis of COF nanoparticles, nanofibers and nanosheets based on the knowledge of crystal growth are reviewed in detail. The understanding related to the polymerization, crystallization and self-assembly process during COF formation will surely make it easier to realize COFs with designed hierarchical architectures for targeted applications.