期刊
ACS APPLIED MATERIALS & INTERFACES
卷 11, 期 47, 页码 44783-44791出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b18062
关键词
covalent organic frameworks; membrane separation; COF nanofilms; solvothermal synthesis; block copolymer
资金
- National Natural Science Foundation of China [21776126, 21825803]
- Program of Excellent Innovation Teams of Jiangsu Higher Education Institutions
- Open Fund of State Key Laboratory of Separation Membranes and Membrane Processes [M1-201702]
Covalent organic frameworks (COFs) with ordered arrays of sub-2 nm regular pores are drawing increasing attention in membrane separation, and it remains highly desirable for effective and controllable strategies to fabricate COF-based membranes. Herein, we demonstrate a perforated polymer-assisted transfer strategy enabling COF nanofilms for molecular separation. Solvothermal synthesis is used for the confined growth of TpPa, a stable, imine-linked COF, on the smooth surfaces of silicon substrates. Continuous, crystalline COF nanofilms are obtained, and their thicknesses are tunable in the range from a few tens to several hundred nanometers depending on monomer concentrations and reaction time. A block copolymer layer is coated on the COF nanofilms, which is then perforated to produce interconnected mesopores by the mechanism of selective swelling-induced pore generation. The perforated polymer coating functions as a protective but permeable layer enabling the easy transfer of the COF nanofilm onto porous substrates. Thus, we obtain a new type of composite membranes with the microporous COF nanofilm as the selective layer, sandwiched between the macroporous substrate and the mesoporous protective layer. The composite membranes exhibit good separation performances with water permeance up to similar to 51 L m(-2) h(-1) bar(-1) and high rejection rates to various dyes. This work demonstrates a new method to prepare COF-based membranes for molecular separation, and the invented perforated polymer-assisted transfer technology is expected to find applications in transferring other ultrathin materials to demanded substrates.
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