Issue 7, 2018, Issue in Progress

Self-exfoliation of 2D covalent organic frameworks: morphology transformation induced by solvent polarity

Abstract

Recently, covalent organic nanosheets (CONs) have emerged as functional two-dimensional (2D) materials for versatile applications. Strong interaction among layers and the instability of borate ester in moisture are the major hurdles to obtain few layered boron-containing CONs by exfoliation of their bulk counterparts. In this paper, we report a facile approach for preparation of few layered borate ester-containing CONs based on electrostatic repulsion of ions. We incorporated organic ionic groups into porous covalent organic frameworks (COFs) and it has been proved that the COFs with quaternary ammonium group could self-exfoliate into few layered ionic covalent organic nanosheets (iCONs) in polar organic solvents. Interestingly, the morphology of the iCOFs-A could be changed from a multilayered aggregation to nanocapsules, or 2D sheets when solvents with different polarity were used. In contrast, non-ionic covalent organic frameworks COFs-B could not self-exfoliate in various solvents. In addition, the self-exfoliated nanosheets could be used to fabricate uniform thin films on SiO2 wafer and the film exhibited explicit optical and electrical properties.

Graphical abstract: Self-exfoliation of 2D covalent organic frameworks: morphology transformation induced by solvent polarity

Supplementary files

Article information

Article type
Paper
Submitted
30 Aug 2017
Accepted
09 Jan 2018
First published
19 Jan 2018
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2018,8, 3803-3808

Self-exfoliation of 2D covalent organic frameworks: morphology transformation induced by solvent polarity

N. Zhang, T. Wang, X. Wu, C. Jiang, F. Chen, W. Bai and R. Bai, RSC Adv., 2018, 8, 3803 DOI: 10.1039/C7RA09647J

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