Copper imprinted on fabric (top) is replaced with a MOF (bottom) capable of detecting and capturing toxic gases. Image: Katherine Mirica.
Copper imprinted on fabric (top) is replaced with a MOF (bottom) capable of detecting and capturing toxic gases. Image: Katherine Mirica.

A durable coating developed by researchers at Dartmouth College can be precisely integrated into fabric to create responsive and reusable materials such as protective equipment, environmental sensors and smart filters. In a paper in the Journal of the American Chemical Society, the researchers report that the coating can respond to the presence of toxic gases in the air by converting them into less toxic substances that become trapped in the fabric.

The coating is based on a conductive metal-organic framework (MOF) developed in the laboratory of corresponding author Katherine Mirica, an associate professor of chemistry at Dartmouth. First reported in 2017, in another paper in the Journal of the American Chemical Society, the MOF was a simple coating that could be layered onto cotton and polyester to create smart fabrics that the researchers named SOFT—Self-Organized Framework on Textiles. In the 2017 paper, they reported that SOFT smart fabrics could detect and capture toxic substances in the surrounding environment.

For the newest study, the researchers found that – instead of the simple coating reported in 2017 – they could precisely embed the MOF into fabrics by using a copper precursor that allows them to create specific patterns and more effectively fill in the tiny gaps and holes between the threads. The researchers found that this MOF could effectively convert the toxin nitric oxide into nitrite and nitrate, and transform the poisonous, flammable gas hydrogen sulfide into copper sulfide. They also reported that the MOF’s ability to capture and convert toxic materials withstood wear and tear, as well as standard washing.

According to Mirica, the versatility and durability of the new coating method would allow the MOF to be applied for specific uses and in more precise locations, such as a sensor on protective clothing or as a filter in a particular environment.

“This new method of deposition means that the electronic textiles could potentially interface with a broader range of systems because they’re so robust,” she said. “This technological advance paves the way for other applications of the framework’s combined filtration and sensing abilities that could be valuable in biomedical settings and environmental remediation.”

The technique could also eventually provide a low-cost alternative to detoxification technologies that are cost prohibitive and limited in where they can be deployed due to their need for an energy source or –as with catalytic converters in automobiles – rare metals.

“Here we’re relying on an Earth-abundant matter to detoxify toxic chemicals, and we’re doing it without any input of outside energy, so we don’t need high temperature or electric current to achieve that function,” Mirica said.

Co-first author Michael Ko, who received his PhD in chemistry from Dartmouth in 2020, initially observed the new process in 2018 when he attempted to deposit the MOF onto thin-film copper-based electrodes. But he instead found that the MOF replaced the copper electrodes.

“He wanted it on top of the electrodes, not to replace them,” Mirica said. “It took us four years to figure out what was happening and how it was beneficial. It’s a very straightforward process, but the chemistry behind it is not, and it took us some time and additional involvement of students and collaborators to understand that.”

The team discovered that the MOF ‘grows’ over copper, replacing it with a material able to filter and convert toxic gases. Ko and co-author Lukasz Mendecki, a former postdoctoral scholar in the Mirica group, investigated methods for applying the MOF to fabric in specific designs and patterns.

Co-first author Aileen Eagleton, a graduate student in the Mirica Group, finalized the technique by optimizing the process for imprinting the MOF onto fabric, as well as identifying how its structure and properties are influenced by chemical exposure and reaction conditions.

Mirica said that future work will focus on developing new multifunctional MOF materials and scaling up the process of embedding the MOF coatings in fabric.

This story is adapted from material from Dartmouth College, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.