JUST ONE WORD FOR THE FUTURE: PLASTICS

One of the most alarming aspects of the increasingly negative impact of humans on our overburdened Earth is the weight of indestructible plastic in our landfills and, worse, in our oceans. Only about 20-30 percent of even the most recyclable of our plastic waste can be refashioned into usable form. The rest must go to the landfill (where it remains forever or leaches out into the environment) or be incinerated.

We’ve seen the horrible results of plastics that find their way to our oceans: floating garbage islands many meters across drifting with the currents; whales and other sea creatures dying with their bellies full of micro-bits of plastic that contaminate the plankton and krill the creatures use as food.

Lost in a sea of plastic garbage.

In the U.S., where plastics based on petrochemicals are ubiquitous, calling for reducing use of the material is a hard sell. Individuals can cut back on their own use of plastic at home, but the problem is bigger than that. Even municipal recycling programs are having a difficult time finding a market for their plastic now that China has stopped accepting it.

Technology, though, may provide part of the answer.  According to a post in Science Daily News, scientists at the U.S. Department of Energy's (DOE) Lawrence Berkeley National Laboratory have developed a new type of plastic that can be recycled by taking it apart at the molecular level, and putting it back together again in any shape, texture, and color. The process can be repeated again and again without loss of performance or quality. Discovery of the new material, called poly(diketoenamine), or PDK, was reported in the journal Nature Chemistry.

The PDK process strips plastic polymers down to their constituent monomers by dunking the material in an acid bath. This also allows for the removal of any additives that might have given the old material its color, flexibility, toughness or other special characteristics. The new material is like a basic building block that can be recombined in all sorts of new ways. PDK can be torn down and built back up multiple times, making it reusable in a circular process, not just a one-time linear process as is true of conventional plastics.

Peter Christensen, a postdoctoral researcher at Berkeley Lab's Molecular Foundry, was lead author of the study that announced the discovery. He admits, “Most plastics were never made to be recycled.” But that was before the team he was part of looked at recycling from “a molecular prospective.”

Christensen’s multidisciplinary team was led by Brett Helms, a staff scientist in Berkeley Lab's Molecular Foundry. The DOE/Lawrence Berkeley National Laboratory reports the other co-authors were undergraduate researchers Angelique Scheuermann (then of UC Berkeley) and Kathryn Loeffler (then of the University of Texas at Austin) who were funded by DOE's Science Undergraduate Laboratory Internship (SULI) program at the time of the study. The overall project was funded through Berkeley Lab's Laboratory Directed Research and Development program.

Team leader Brett Helms is clear about the potential impact of the discovery of PDK on our environmental future. "We're at a critical point where we need to think about the infrastructure needed to modernize recycling facilities for future waste sorting and processing," said Helms. "If these facilities were designed to recycle or upcycle PDK and related plastics, then we would be able to more effectively divert plastic from landfills and the oceans. This is an exciting time to start thinking about how to design both materials and recycling facilities to enable circular plastics." 

Cheers, Donna

*Information for this post taken from: “Plastic gets a do-over: Breakthrough discovery recycles plastic from the inside out,” Science Daily News, DOE/Lawrence Berkeley National Laboratory, May 7, 2019.  https://www.sciencedaily.com/releases/2019/05/190507110452.htm