Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plastic gets a do-over: Breakthrough discovery recycles plastic from the inside out

07.05.2019

Scientists from Berkeley Lab have made a next-generation plastic that can be recycled again and again into new materials of any color, shape, or form

Light yet sturdy, plastic is great - until you no longer need it. Because plastics contain various additives, like dyes, fillers, or flame retardants, very few plastics can be recycled without loss in performance or aesthetics.


Unlike conventional plastics, the monomers of PDK plastic could be recovered and freed from any compounded additives simply by dunking the material in a highly acidic solution.

Credit: Peter Christensen et al./Berkeley Lab

Even the most recyclable plastic, PET - or poly(ethylene terephthalate) - is only recycled at a rate of 20-30%, with the rest typically going to incinerators or landfills, where the carbon-rich material takes centuries to decompose.

Now a team of researchers at the U.S. Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) has designed a recyclable plastic that, like a Lego playset, can be disassembled into its constituent parts at the molecular level, and then reassembled into a different shape, texture, and color again and again without loss of performance or quality. The new material, called poly(diketoenamine), or PDK, was reported in the journal Nature Chemistry.

"Most plastics were never made to be recycled," said lead author Peter Christensen, a postdoctoral researcher at Berkeley Lab's Molecular Foundry. "But we have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective."

Christensen was part of a multidisciplinary team led by Brett Helms, a staff scientist in Berkeley Lab's Molecular Foundry. The other co-authors are 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.

All plastics, from water bottles to automobile parts, are made up of large molecules called polymers, which are composed of repeating units of shorter carbon-containing compounds called monomers.

According to the researchers, the problem with many plastics is that the chemicals added to make them useful - such as fillers that make a plastic tough, or plasticizers that make a plastic flexible - are tightly bound to the monomers and stay in the plastic even after it's been processed at a recycling plant.

During processing at such plants, plastics with different chemical compositions - hard plastics, stretchy plastics, clear plastics, candy-colored plastics - are mixed together and ground into bits. When that hodgepodge of chopped-up plastics is melted to make a new material, it's hard to predict which properties it will inherit from the original plastics.

This inheritance of unknown and therefore unpredictable properties has prevented plastic from becoming what many consider the Holy Grail of recycling: a "circular" material whose original monomers can be recovered for reuse for as long as possible, or "upcycled" to make a new, higher quality product.

So, when a reusable shopping bag made with recycled plastic gets threadbare with wear and tear, it can't be upcycled or even recycled to make a new product. And once the bag has reached its end of life, it's either incinerated to make heat, electricity, or fuel, or ends up in a landfill, Helms said.

"Circular plastics and plastics upcycling are grand challenges," he said. "We've already seen the impact of plastic waste leaking into our aquatic ecosystems, and this trend is likely to be exacerbated by the increasing amounts of plastics being manufactured and the downstream pressure it places on our municipal recycling infrastructure."

Recycling plastic one monomer at a time

The researchers want to divert plastics from landfills and the oceans by incentivizing the recovery and reuse of plastics, which could be possible with polymers formed from PDKs. "With PDKs, the immutable bonds of conventional plastics are replaced with reversible bonds that allow the plastic to be recycled more effectively," Helms said.

Unlike conventional plastics, the monomers of PDK plastic could be recovered and freed from any compounded additives simply by dunking the material in a highly acidic solution. The acid helps to break the bonds between the monomers and separate them from the chemical additives that give plastic its look and feel.

"We're interested in the chemistry that redirects plastic lifecycles from linear to circular," said Helms. "We see an opportunity to make a difference for where there are no recycling options." That includes adhesives, phone cases, watch bands, shoes, computer cables, and hard thermosets that are created by molding hot plastic material.

The researchers first discovered the exciting circular property of PDK-based plastics when Christensen was applying various acids to glassware used to make PDK adhesives, and noticed that the adhesive's composition had changed. Curious as to how the adhesive might have been transformed, Christensen analyzed the sample's molecular structure with an NMR (nuclear magnetic resonance) spectroscopy instrument. "To our surprise, they were the original monomers," Helms said.

After testing various formulations at the Molecular Foundry, they demonstrated that not only does acid break down PDK polymers into monomers, but the process also allows the monomers to be separated from entwined additives.

Next, they proved that the recovered PDK monomers can be remade into polymers, and those recycled polymers can form new plastic materials without inheriting the color or other features of the original material - so that broken black watchband you tossed in the trash could find new life as a computer keyboard if it's made with PDK plastic. They could also upcycle the plastic by adding additional features, such as flexibility.

Moving toward a circular plastic future

The researchers believe that their new recyclable plastic could be a good alternative to many nonrecyclable plastics in use today.

"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," said Helms.

The researchers next plan to develop PDK plastics with a wide range of thermal and mechanical properties for applications as diverse as textiles, 3D printing, and foams. In addition, they are looking to expand the formulations by incorporating plant-based materials and other sustainable sources.

###

The Molecular Foundry is a DOE Office of Science User Facility that specializes in nanoscale science.

This work was supported by the DOE's Laboratory Directed Research and Development (LDRD) program with additional funding provided by the DOE Office of Science through the SULI program.

The technology is available for licensing and collaboration. If interested, please contact Berkeley Lab's Intellectual Property Office, ipo@lbl.gov.

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 13 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab's facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy's Office of Science.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Media Contact

Laurel Kellner
LKellner@lbl.gov
510-590-8034

 @BerkeleyLab

http://www.lbl.gov 

Laurel Kellner | EurekAlert!
Further information:
https://newscenter.lbl.gov/2019/05/06/recycling-plastic-from-the-inside-out/
http://dx.doi.org/10.1038/s41557-019-0249-2

More articles from Ecology, The Environment and Conservation:

nachricht Treatment of saline wastewater during algae utilization
14.05.2019 | Jacobs University Bremen gGmbH

nachricht Loss of habitat causes double damage to species richness
02.04.2019 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

Im Focus: A step towards probabilistic computing

Working group led by physicist Professor Ulrich Nowak at the University of Konstanz, in collaboration with a team of physicists from Johannes Gutenberg University Mainz, demonstrates how skyrmions can be used for the computer concepts of the future

When it comes to performing a calculation destined to arrive at an exact result, humans are hopelessly inferior to the computer. In other areas, humans are...

Im Focus: Recording embryonic development

Scientists develop a molecular recording tool that enables in vivo lineage tracing of embryonic cells

The beginning of new life starts with a fascinating process: A single cell gives rise to progenitor cells that eventually differentiate into the three germ...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Producing tissue and organs through lithography

23.05.2019 | Life Sciences

Summit charts a course to uncover the origins of genetic diseases

22.05.2019 | Life Sciences

New study finds distinct microbes living next to corals

22.05.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>