Solving the Problem of Plastics

Solving the Problem of Plastics

Chemistry brought us plastics, and chemistry is now challenged to save us from these synthetic materials and their unintended environmental consequences. Enter Colorado State University polymer researchers.

by Anne Manning | Photo above by Caroline Power | Campus photography by William A. Cotton

Tossing a plastic bottle into a recycling bin, rather than throwing it in the trash, is helping to save the planet, right? Don’t try that reasoning on Eugene Chen.

The CSU chemistry professor refutes any notion that current recycling practices make a dent in one of humanity’s greatest scourges: plastic. By the latest estimates, less than 10 percent of all commercial plastics are recycled, meaning partially reconstituted to extend their usefulness. As a result, Chen says, about 56 million tons of plastic trash are overflowing our landfills and bobbing in our oceans. By 2050, business as usual will mean more plastic than fish by weight in the oceans, according to the World Economic Forum.

Chemistry brought us plastics, and chemistry is now challenged to save us from these synthetic materials and their unintended environmental consequences. Chen and his team are at the forefront of creating new polymer materials, with properties that rival conventional, petroleum-based, nonrecyclable plastics – and are economically viable. They’re also redefining what it means to recycle.

“The biggest question is, can we compete?” Chen said. “Will our material be useful? Will it have the properties that rival current, long-lasting, durable plastics? That’s the goal.”

Eugene Chen’s lab is developing a novel recyclable polymer that could one day compete with conventional plastics. The team’s material is lightweight and flexible, much like conventional plastics. Garret Miyake’s lab specializes in polymer-based photonic crystals, such as color-reflecting crystals that could one day be used in reflective window coatings.

Chen’s CSU research group is one of 11 that recently moved into the new Chemistry Research Building, opened in August. Boasting open, collaborative labs and modern air-handling systems, the state-of-the-art building is advancing cutting-edge synthetic chemistry under its roof every day.

Most work in the Chen lab falls into the category of green and sustainable chemistry: devising environmentally friendly alternatives to traditional chemical products and processes, as well as new polymer materials. Included in these efforts is research to create a novel organic polymer that, after its useful life, can be heated or catalyzed back to its building-block molecule, called a monomer. This, Chen said, would be a truly recyclable material: one with a circular life cycle that produces essentially no waste and recovers the material’s value after end use.

Compare that with the synthetic polymers littering Earth today: plastics, rubbers, ceramics, and coatings, among them. Characterized by long chains of repeating units with strong chemical bonds, synthetic polymers are successful for the same reason they are problematic. We love plastics because they’re durable and strong; that’s also why most of them don’t degrade in landfills.

A year after publishing their first demonstration of a truly recyclable polymer in the journal Nature Chemistry, Chen’s team is hard at work on a second-generation recyclable polymer. It has a higher thermal stability and better mechanical properties, akin to flexible conventional plastics. “We are inching closer, especially with this second generation of recyclable polymers, to materials with properties that make them practical and useful. We’re very excited about it,” Chen said.

Green chemistry can take many forms beyond making better plastics. Garret Miyake, an assistant professor of chemistry, is another polymer chemist who makes the new Chemistry Research Building his academic home. He and his team are devising new molecular structures that could lead to products for environmentally friendly applications.

A former graduate student of Chen’s, Miyake joined the Colorado State faculty in 2017. He was drawn back to CSU not only by the community of like-minded researchers he discovered here but also by its cutting-edge facilities.

“The capabilities we have here are not matched in many places,” Miyake said.

Miyake’s lab specializes in polymer-based photonic crystals that reflect and transmit different wavelengths of visible light, depending on their nanostructures and the size of the polymers.

One of his goals is to replace toxic dyes and chemicals with so-called structural color – the same natural phenomenon found in butterfly wings. With this approach, color would be built into a material’s nanostructure, rather than being added later.

“We develop new catalytic methods that allow you to make designer polymers,” Miyake said.

“There are a bazillion ways to make polymers now that are awesome, and they all have their strengths and weaknesses. If we want to target new applications and make new types of materials, we have to develop new ways to make them.”

One of their projects is a transparent polymer that could be suspended in liquid and sprayed onto a window pane. The polymer’s nanostructure would reflect heat, providing a low-cost retrofit to reduce the need for air conditioning or tinted glass in buildings or automobiles.

Some of Miyake’s students are applying structural color to 3-D printing applications by making dye-free inks that intrinsically reflect purple, green, and other hues based on their polymeric nanostructure.

That’s one of the best things about working in Miyake’s lab: The possibilities for applications are endless, said graduate student Bret Boyle, who works on the photonic crystals.

“We have a couple different routes we’re taking, but in the future we can think about things like optical computing, light waveguides, surgical tools, and a lot of different things,” Boyle said.

As exciting as the science is, “probably the most exciting experiment that I run is learning how to educate students,” Miyake said. He wants to cultivate independent, motivated students who have freedom to work on their own projects. It’s a culture Miyake adopted from Chen.

Chen hopes to continue this experiment and expand the community of polymer chemistry at CSU through the Center for Sustainable Monomers and Polymers. Chen leads the center with input from a 10-member faculty steering committee and support from the Office of the Vice President for Research. The center, sandwiched between the Chen and Miyake labs, houses state-of-the-art polymer characterization instruments that help the researchers understand aspects of their new creations, such as thermal resistance and mechanical durability.

Chen’s vision is to expand the scope of the center with an increasing emphasis on polymer education, because he knows that saving the world from polluting, nonrecyclable plastics will require the talents of future polymer chemists.

“We have fantastic facilities for polymer characterizations, and we still have new instruments coming in,” Chen said. “It’s going to be a great center for polymer research and education, as it not only performs cutting-edge fundamental research, but also attracts the best students and trains them as our future professional leaders.”

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