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Chemical research made cleaner, more sustainable in University lab

University research team designs process to reduce degradation in synthetic polymer

By
Science and Research Editor
Wednesday, December 4, 2019

A chemistry lab is typically a busy place; ingredients and materials line the space as the beeps of machines and squeals of steam fill the air. Projects can take years to come to fruition in even the busiest of labs, but one such lab at the University has recently reached not one but two major research milestones.

First, the team of researchers produced a commonly used synthetic polymer known as Zylon, which can be found in batteries, body armor, motorsports equipment and vehicles and even at SpaceX. Typically, the way this polymer is made can cause it to degrade in important products like body armor, but the research team managed to produce the polymer without the process that can cause it to degrade. The team also advanced the effort to make chemical sciences more sustainable — they  incorporated new methods of “green chemistry” that they hope can drastically reduce chemical waste in future chemical research.

Zylon, also known as PBO, is rigid organic polymer with high tensile strength and thermal resistance. Typically, the use of polyphosphoric acid as the catalyst to create the polymer leaves traces of the acid inside the fibers, which can lead to degradation at rapid rates. To resolve this problem, the researchers used composite nanoparticles — nanomaterials composed of two or more components with special chemical properties — as catalysts and decreased the number of steps in the polymerization process, said Professor of Chemistry and Professor of Engineering Shouheng Sun.

The team consisted of many faculty members, including Sun, Chao Yu, a postdoctoral fellow in the chemistry department and first author of the study and Assistant Professor of Chemistry Jerome Robinson, alongside several others to create an interdisciplinary approach across varying departments. The project required the knowledge and expertise of organic chemistry, polymer characterization, nanoparticle synthesis, material properties and more, Robinson said. “I thought it was a really nice collaborative project between different faculty at Brown. … We can leverage all these expertises to come together into this area that’s pretty interdisciplinary,” he added.

The team made the polymer in a more compact “one-pot” process — not unlike “one-pot” cooking — and incorporated nanoparticles as the catalyst, which greatly decreased the chemical waste created by this process. In lieu of pure hydrogen, the team used formic acid, a biocompatible and non-toxic substance, to produce hydrogen in the polymerization, Sun said. Using hydrogen gas requires a pressurized tank and specialized equipment, Robinson said, but using a liquid such as formic acid can eliminate some of the inherent challenges associated with transporting and using gas. Once the polymer is synthesized, some of the materials can be collected and reused, leading to greater sustainability and a “greener” chemical lab. Formic acid can actually be regenerated from cellulose or CO2 reduction, allowing for greater reusability, Sun said. And because of the nanoparticles, the polymer resists degradation from heat and acid, Sun said.

The use of a “one-pot” multiple reaction method has applications in a wide range of chemical research, ranging from the creation of antibiotic compounds to the production of seatbelts in racecars, Sun said. Though Sun hopes to continue his research, he does not plan to expand into a commercial field.  “We’re in academia … We’re not in a position to commercialize something … We educate students and get students involved. Hopefully one of our students, your friends, can take it over and commercialize it. We would like to see that,” Sun added.

The University research team hopes to continue to use more green methods to further promote sustainability and reusability in the field of chemical research.

“We want to make sure the process can proceed under green chemistry conditions for future environmentally friendly reactions,” Sun said.

“The idea of using renewable sources of hydrogen in the lab … is definitely getting a lot of traction. … I think the idea of using nanoparticles to control polymer properties is a totally unexplored region of space … (It’s something) we’re quite excited about,” Robinson said.

The project was initially funded in part by the U.S. Army Research Laboratory and U.S. Army Research Office. The ARO is an element of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory and conducts research with more than 250 universities. Twenty-four previously funded researchers have become Nobel laureates, wrote a public affairs specialist for the ARO in an email to The Herald.

When the grant was initially rewarded to University researchers by the ARO, the main research topic was electrocatalysts, said Robert Mantz, program manager of electrochemistry and chemical division chief for the ARO. “Basic research has a way of going in unexpected directions … When I initially funded it, I was not thinking of PBO.  … You can’t always predict the future, but if you fund good ideas and you have people that are doing really good science, those opportunities open up,” he added.

“I am trying to fund science that is army relevant but hopefully leads to breakthroughs that change the way the army does business in the future,” he added.

Correction: A previous version of this article named a public affairs specialist for the ARO who said that “twenty-four previously funded researchers have become Nobel laureates.” The specialist requested anonymity for fear of professional repercussions. The article has been updated to reflect that change. The Herald regrets the error.

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