College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, P. R. China.
Department of Dermatology, Second Xiangya Hospital, Central South University, Changsha 410011, P. R. China.
Chem Soc Rev. 2019 Jan 21;48(2):488-516. doi: 10.1039/c8cs00376a. Epub 2018 Dec 19.
As a newly emerging class of porous materials, covalent organic frameworks (COFs) have attracted much attention due to their intriguing structural merits (e.g., total organic backbone, tunable porosity and predictable structure). However, the insoluble and unprocessable features of bulk COF powder limit their applications. To overcome these limitations, considerable efforts have been devoted to exploring the fabrication of COF thin films with controllable architectures, which open the door for their novel applications. In this critical review, we aim to provide the recent advances in the fabrication of COF thin films not only supported on substrates but also as free-standing nanosheets via both bottom-up and top-down strategies. The bottom-up strategy involves solvothermal synthesis, interfacial polymerization, room temperature vapor-assisted conversion, and synthesis under continuous flow conditions; whereas, the top-down strategy involves solvent-assisted exfoliation, self-exfoliation, mechanical delamination, and chemical exfoliation. In addition, the applications of COF thin films including energy storage, semiconductor devices, membrane-separation, sensors, and drug delivery are summarized. Finally, to accelerate further research, a personal perspective covering their synthetic strategies, mechanisms and applications is presented.
作为一类新兴的多孔材料，共价有机框架（COFs）由于其有趣的结构优点（例如，全有机骨架、可调节的孔隙率和可预测的结构）而引起了广泛关注。然而，块状 COF 粉末的不溶性和不可加工性限制了它们的应用。为了克服这些限制，人们已经投入了相当大的努力来探索具有可控结构的 COF 薄膜的制造，这为它们的新应用开辟了道路。在这篇评论中，我们旨在提供 COF 薄膜制造的最新进展，不仅包括在基底上支撑的薄膜，还包括通过自下而上和自上而下的策略制备的自由-standing 纳米片。自下而上的策略包括溶剂热合成、界面聚合、室温气相辅助转化和连续流动条件下的合成；而自上而下的策略包括溶剂辅助剥离、自剥离、机械分层和化学剥离。此外，还总结了 COF 薄膜在储能、半导体器件、膜分离、传感器和药物输送等方面的应用。最后，为了加速进一步的研究，提出了个人视角，包括它们的合成策略、机制和应用。
