Study on the Morphologies of Covalent Organic Microporous Polymers: the Role of Reaction Solvents

Abstract

Two-dimensional conjugated microporous polymers (CMPs) composed of alternative phenylene and ethynylene units are synthesized, by cross-coupling polymerization of 1,3,5-triethynylbenzene and 1,3,5-tribromobenzene with various solvents. Our work shows that the morphology of CMPs is greatly affected by the choice of solvents used in synthesis. Sphere, tubular, and plate-like structures are received by using the toluene, p-xylene, and mesitylene solvents, respectively. Our results demonstrate that the morphology of CMPs affects the storage capacity for organic solvents remarkably, with the plate-like CMP showing best performance. This work is expected to provide useful guidance to rationally design CMPs as absorbent materials for organic solvents.

Morphological Diversity in Nanoporous Covalent Organic Materials Derived from Viologen and Pyrene

“…[12] In order to design COPs with improved functionality, considerable research has been undertaken to understand the relationship between the morphologies and properties of these materials. [13][14][15] It has been observed that the morphology of COPs can be tuned by changing the symmetry of their constituent building blocks, but precise regulation of COP nanostructure remains a challenging task.…”

“…The two materials were characterized by Fourier-transform infrared (FTIR) spectroscopy, solid-state cross polarization magic angle spinning (CP-MAS) 13 C NMR spectroscopy, and elemental analysis (Table S1). The disappearance of amine absorption bands at 3342 cm À1 (NÀH asymmetric stretch) and 3361 cm…”

“…[12] In order to design COPs with improved functionality, considerable research has been undertaken to understand the relationship between the morphologies and properties of these materials. [13][14][15] It has been observed that the morphology of COPs can be tuned by changing the symmetry of their constituent building blocks, but precise regulation of COP nanostructure remains a challenging task.Syntheses of covalent organic hollow tubes (COTs) and nanosheets (CONs) are of interest because their large surface areas facilitate the adsorption of small molecule guests. Porous, template-free COPs with uniform tube morphology have been used for device manufacturing [16] and catalysis, [17,18] but reports of the synthesis and application of this type of material remain scarce.…”

“…CP-MAS 13 C NMR spectra of the polymers (Figures S2-S3) show broad peaks at d = 127-147 ppm, which correspond to their aryl groups. The solid state 13 C NMR spectrum of COTs shows a band at d = 96 ppm, which corresponds to the carbons of the alkynes.…”

“…CP-MAS 13 C NMR spectra of the polymers (Figures S2-S3) show broad peaks at d = 127-147 ppm, which correspond to their aryl groups. The solid state 13 C NMR spectrum of COTs shows a band at d = 96 ppm, which corresponds to the carbons of the alkynes. Powder X-ray diffraction (PXRD) patterns of the two COPs ( Figure S4) revealed a characteristic broad peak consistent with their amorphous nature and the PXRD spectra of previously reported conjugated microporous polymer networks.…”