Engineers have created an inventive method to manufacture covalent organic frameworks, which are unique materials capable of trapping gases, purifying water, and accelerating chemical reactions.
Engineers at Rice University have come up with a groundbreaking technique for producing covalent organic frameworks (COFs), specialized materials that can capture gases, clean water, and enhance chemical reactions. These COFs hold promise for tackling major environmental issues, such as energy storage and pollution management. For instance, they could be instrumental in removing “forever chemicals” or per- and polyfluoroalkyl substances (PFAS) from the environment.
Chemical engineer Rafael Verduzco and his team at Rice have outlined a novel approach to synthesizing high-quality COFs in a cost-effective manner with high output, as detailed in a study published in ACS Applied Materials and Interfaces, which will feature on the cover of an upcoming issue. Their research includes a thorough examination of the pros and cons of various synthesis techniques and introduces a flexible and affordable method for creating COFs. This process employs a multiflow microreactor and precise adjustment of input-output mechanisms.
“We constructed a compact, continuous production system—much like a small factory set up on a lab bench—where the components for COFs are consistently mixed and reacted, instead of being combined all at once in a large vessel,” explained Safiya Khalil, a Rice doctoral graduate and the lead author of the study.
The team discovered that one of the COFs created through flow synthesis was more effective than those made through other methods in breaking down perfluorooctanoic acid (PFOA), a PFAS compound linked to various health issues, including cancer and reproductive harm.
“This promising result adds to the increasing body of evidence suggesting that COFs might become crucial in creating cleaner, more effective technologies for contaminant removal,” stated Verduzco, who is a professor and associate chair of chemical and biomolecular engineering at Rice and the study’s corresponding author.
COFs are crystalline polymers made from small, repeating units that are bonded together into tiny, sponge-like structures. They are notable for their porosity, high surface area, and customizable molecular structure—traits that can be utilized across various applications, such as semiconductors, sensors, drug delivery, and filtration. However, the slow and costly production methods have hindered their widespread use.
“We believe this method will facilitate the large-scale production of COFs and speed up the exploration of new formulations,” remarked Khalil, who obtained her Ph.D. in chemical and biomolecular engineering from Rice, having previously worked in Verduzco’s Polymer Engineering Laboratory.
Khalil compared the new method to baking cookies on demand in small batches rather than preparing them all at once in a single large batch. While flow reactor synthesis for COFs isn’t new, the Rice team’s technique is notable for its integration of continuous synthesis and processing of two distinct COF chemistries, enabling a broader variety of macroscopic formats.
“This method allows you to continually produce fresh cookies while fine-tuning the temperature and mixing at each stage to achieve optimal quality every time,” Khalil said. “It is quicker, consumes less energy, and provides better control over the final product.”
Conventional methods of synthesizing COFs typically require high temperatures, elevated pressures, and toxic organic solvents, which limits their extensive production and application. The flow synthesis strategy from the research team not only allows for quicker production of COFs but also leads to the formation of COFs with superior crystallinity.
The additional evidence showing that one of the newly synthesized COFs effectively decomposed a “forever chemical” underscores the practical advantages of the new approach. The decomposition process, referred to as photocatalytic degradation, is light-activated and takes place at room temperature.
“Visualize these COFs as powerful sponges equipped with ‘sunlight engines’ capable of breaking down harmful chemicals at a much faster rate than existing methods,” Khalil stated. “One of the COFs we generated outperformed traditional materials like titanium dioxide, a common photocatalyst used for pollution control, in breaking down PFOA.”
The research received funding support from the Ministry of Education of the United Arab Emirates and the Welch Foundation (C-2124).
