Nanospheres to Nanosheets: Unfolding the Morphological Influence of Microporous Organic Polymers on Micropollutants Removal

Abstract

<p>Nanoporous organic polymers with distinct morphologies are of immense interest for a broad spectrum of applications ranging from catalysis to molecular separation, energy storage, and energy conversion. However, developing facile and versatile methodologies to obtain well-orchestrated morphologies along with high specific surface area pertinent to a specific application is still a formidable challenge. The design of the task-specific networks can be benefitted through further analysis of subtle variations in the polymerization conditions. Herein, we have critically examined the fabrication of triptycene-based hypercrosslinked polymers (HCPs), exhibiting contrasting morphologies developed through three distinct polymerization routes. Astonishingly, a remarkable variation of nanostructured morphology of irregular aggregates, nanospheres, and nanosheets was noticeable in the resultant network polymers through Friedel-Crafts crosslinking using dimethoxymethane as an external crosslinker, Scholl coupling, and solvent knitting using dichloromethane as an external crosslinker and solvent, respectively. The dramatic role of reaction temperature, catalysts, and solvents driving the formation of specific nanostructured HCPs was elucidated. Mechanistic investigations coupled with spectroscopic and microscopic studies revealed that the 2D-nanosheets of highly porous solvent-knitted HCP (SKTP, S<sub>BET</sub>: 2385 m<sup>2</sup> g<sup>-1</sup>) evolved through the hierarchical self-assembly of rigid nanospheres into nanoribbons followed by the formation of nanosheets. We further demonstrated a structure-activity correlation of the pristine as well as post-synthetically sulfonated HCPs for the removal of a gamut of organic micropollutants from water. Solvent knitted triptycene polymer (SKTP) and its sulfonated derivative (SKTPS, S<sub>BET</sub>: 1444 m<sup>2</sup> g<sup>-1</sup>) owing to high specific surface areas, excellent dispersity in water, and better accessibility of analytes through 2D-sheet like morphology exhibited ultrafast sequestration (30 s to 5 min) of an extensive array of persistent organic micropollutants, including ionic dyes, plastic components, steroids, antibiotic drugs, and herbicides with excellent recyclability. The current study holds the promise that a delicate control over the morphologies of nanoporous polymers by tuning the fabrication conditions paves the way for the development of advanced porous materials for environmental remediation.</p>

Solvent-Directed Morphological Transformation in Covalent Organic Polymers

“…It was difficult to find the individual domain due to the high agglomeration, and the morphology was found to be of the distorted spherical type. This study provided clear evidence that not only the solvent but also the type of metals can significantly affect the morphology of the resulting materials, as is evident in previous reports (Gao et al, 2018;Giri et al, 2022); further studies relating to the effect of metal are presently under progress in our group. In order to stick to the metal-free morphology transformation, we further study the chemical nature of the F-COP DMF or C-COP DMSO using the XPS analysis.…”

“…However, it is challenging to acquire the morphologycontrolled nanostructure due to the unrestricted kinetic of polymerization (Trewin and Cooper, 2010). Various synthesis methods have been developed involving template-assisted, external cross-linkers, and solvent knitting methods (Thomas et al, 2008;Zhao et al, 2013;Wang et al, 2017;Gao et al, 2019;Giri et al, 2022). Although a wide range of substrates have been used to design and synthesize newer types of COPs, most of these approaches require either an external cross-linker or a catalyst.…”

Photo‐Modulating CO2Uptake of Hypercross‐linked Polymers Upcycled from Polystyrene Waste

“…[28] HCPs comprise aromatic molecules that are crosslinked with methylene bridges via Friedel Crafts alkylation of aromatic polymers and monomers in halogenated solvents. [29] The microporosity of HCPs is dependent on the crosslinking degree and can be tailored through substrate [30][31][32] and solvent [33,34] choices, the use of crosslinking reagents such as formaldehyde acetal [35] and chemical approachespostpolymerisation crosslinking, [36] internal crosslinking [37] and external crosslinking of monomers. [38] HCPs can be synthesized from polystyrenic plastic wastes such as Styrofoam (tradename for expanded polystyrene).…”