posted on 2023-11-17, 19:34authored byTong Ju, Ming Liu, Xiansong Shi, Ankang Xiao, Zhe Zhang, Jingtao Wang, Yatao Zhang, Yong Wang
Nanosheets derived from two-dimensional
covalent organic frameworks
(2D COFs) are increasingly desirable in various fields. While breakthroughs
in the chemical and physical delamination of 2D COFs are rising, precisely
regulating the growth of the COF nanosheets has not been realized
yet. Herein, we report an effective strategy of polymer-manipulated
crystallization to accurately control the growth of COF nanosheets.
Chemically asymmetric polyvinylpyrrolidone (PVP) is developed as the
manipulator that selectively interacts with the aldehydes and (100)
facet to induce anisotropic growth of COFs. The number of PVP constitutional
units determines this specific interaction, leading to molecularly
thin but thickness-controllable nanosheets with excellent dispersity.
We process these nanosheets into robust A4-sized membranes for ultraselective
molecular separation. The membrane intercalated with long-chain PVP
demonstrates largely improved performance, surpassing the reported
COF membranes. This work reports a strategy for anisotropically crystallizing
2D COFs to yield processable nanosheets toward practical applications.