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Transforming Plastics Recycling using Discovery Science

The Berkeley Lab’s Molecular Foundry user facility developed a polymer they could degrade and then rebuild. This could lead to circular plastics that can be reused repeatedly again

Recycling systems currently in place don’t give an answer to this problem. Within the U.S., less than 10% of plastics that are discarded are reused. The remainder are disposed of into landfills or burnt in Incinerators.

If we could collect all of the plastics that are discarded, there would be very few use. Many recycling facilities heat the plastic and shape it into a new shape. However, unlike glass and metal, the more frequently used plastic gets recycled, the less valuable it is. Its value decreases, and it is used in fewer products.

The possibilities for new solutions are endless. However, they will require innovation at all levels, from basic research in labs to the commercial collection methods used in the neighborhoods. To help facilitate this change Department of Energy’s Office of Science is supporting discovery research in order to tackle the issue.

Pervasive and Complex

Plastics are substances that are created by connecting tiny molecular units and over again, creating large chains of atoms. These chains of atoms can be known as macromolecules. They’re composed of chemical bonds that connect carbon with other elements, such as nitrogen, oxygen, as well as hydrogen.

The seemingly straightforward structure conceals the vast the complexity. Once the bonds are formed, they are very difficult to break. This is the reason why plastics are sturdy. In order to increase their versatility, the majority of plastics are dyed, as well as other ingredients. Some products use multiple types of plastics, for example, squeeze bottles of applesauce, which contain at least nine layers of various substances. After a chunk of plastic is taken away, it’s mixed in with a variety of other kinds of plastic. The various substances in the garbage stream make plastics extremely difficult to recycle.

“That complexity is going to be a huge challenge from a plastics recycling perspective,” said LaShanda Korley, materials science and chemical and biomolecular engineering professor at the University of Delaware and director of the brand new Center for Plastics Innovation, an DOE Energy Frontier Research Center (EFRC).

Research in the past has mostly focused on creating new materials. There was very little investment in developing materials that are easily reused.

“We have almost been too successful at designing synthetic materials,” Scott said. Scott who has spent the bulk of her life learning to create new plastics. “The challenge now is, how do we undo that?”

Not-So-Basic Research

The new processes that transform plastics call for a new scientific foundation. To address these issues, the Office of Science’s Basic Energy Sciences convened a roundtable. The group formulated the report for 2019. 

“From a science perspective, we have really barely touched the surface of understanding what needs to be done and how to do it,” said Aaron Sadow, chemistry professor at Iowa State University, senior scientist at DOE’s Ames Laboratory, and director of a new EFRC which is called The Institute for Cooperative Upcycling of Plastics.

The most obvious concern is how to break the plastic, which is tough chemical bonds. The current methods require a lot of energy as well as high temperatures. Additionally, the majority of methods break bonds randomly. They don’t give scientists control over the location and method bonds break. They require this control to develop new products. The process can also create many unwanted products, or create greater bonds, which will be difficult to break down later.

“We’ve learned that the processes are probably much more simple than we anticipated in some sense and way more complex in others,” Sadow explained. “We’ve learned that chain length matters a lot and we didn’t necessarily expect that.”

After the chains have been fragmented into smaller parts, Researchers then want to understand how to reassemble them so that the bonds are able to be broken in the future. In addition, they’re looking into how they can convert an already existing polymer to a totally new product.

Huge Problems Require Big Solutions

“There’s a heck of a lot of plastics out there,” said Karen Winey, materials science and engineering professor at the University of Pennsylvania and co-chair of the DOE Basic Energy Sciences Roundtable on Chemical Upcycling of polymers. “It’s a huge, diverse problem, so we need lots of solutions.”

There are two major ways to go about it that can be taken: creating circular plastics or recycling existing plastics.

Circular plastics are able to be reduced to their basic elements and then reassembled into new products again and again. In order to achieve circular recycling this method would require to create plastics that are as efficient as those that are already in use that break up only if you wish they to, and are efficient in terms of energy and cost. In order to meet these needs, you may need to create new links for the polymer chain we have.

However, we might have discovered one -just by chance. Researchers from the Molecular Foundry, an Office of Science user facility located at Lawrence Berkeley National Laboratory, discovered that a particular polymer they created seemed to behave strangely when they applied an acid to cleanse the the glassware they used to prepare it. Brett Helms, a Molecular Foundry scientist, explained, “We noticed that parts of the material would start to flake off of our amber-colored resins, like you would see in Jurassic Park.” The flakes appeared strangely similar to the initial material they used to create the polymer.

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Jane S. King

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