Could Plastic Waste Become History?
There are plenty of articles and social media posts on the plastic waste management crises, including numerous pieces on the negative impacts of plastic pollution on human and animal health. This is why news that recent scientific advancements show the potential for plastic to be engineered with a pre-programmed lifespan has been warmly welcomed.
As the authors of this study documenting these achievements explain, controlling the rate at which polymers break down is essential for developing sustainable materials, and a possible solution to global plastic waste.
The New Scientist reports, inspired by natural polymers like DNA, a research team of chemists at Rutgers, The State University of New Jersey, has devised a way to engineer plastic to allow it to break down in days, months, or years, when it is no longer needed, rather than it polluting the environment for centuries. The technique they have been working on is all about creating plastics with finely-tuned lifespans that could break down into harmless molecules fast in the natural environment when the material is no longer needed.
Thinking Outside The Box
This creative innovation from a team of chemistry researchers at Rutgers University, led by Assistant Professor, Yuwei Gu, aims to replace the current “linear” model of plastic production, where materials are designed to last for centuries, but are often used for just a few minutes in the case of items like a bag or drinking straw.
Significantly, conventional plastic waste can take from an estimated two decades to 1,000 years to decompose, rather than disappearing completely. The New Scientist details that in 2022, over a quarter of a billion tonnes of plastic was discarded globally, with only 14 percent being recycled. Further, the promise of a practical, biodegradable plastic has been around for at least three and a half decades, but many of these materials are hard to compost.
Rutgers Today recounts how Gu was hiking through Bear Mountain State Park in New York, when he had a lightbulb moment after seeing plastic bottles strewn across the trail and the surface of a nearby lake. These jarring sights made him stop in his tracks. Nature makes plenty of long-stringed molecules called polymers, including DNA, that eventually break down, he pondered, so why can’t plastic do this?
“Biology uses polymers everywhere, such as proteins, DNA, RNA and cellulose, yet nature never faces the kind of long-term accumulation problems we see with synthetic plastics,” Gu told Rutgers Today. And it was in the woods that the answer dawned on him. The difference has to lie in chemistry.
Gu and his colleagues turned to biomimicry to try to replicate natural processes to create plastics that break down under everyday conditions after doing their job, without heat or harsh chemicals.
Interesting Engineering highlights that this innovation has been achieved without relying on new chemicals, but through the use of “prefolded” molecules. The key to the discovery was how the researchers arranged components of the plastic’s chemical structure so they were in the perfect position to start breaking down when triggered, but until then, held up perfectly for real world use.
These “programmable plastics” can be set to self-destruct precisely when no longer needed, when exposed to particular environmental triggers such as moisture, sunlight or even small electric pulses, Science Blog explains.
What are the Likely Applications for ‘Programmable Plastic?’
In efforts to prevent long-term pollution, programmable plastic technology is being developed for sustainable, single-use packaging, military applications, and secure data storage devices.
Gu explains this to the New Scientist as follows: “This strategy works best for plastics that benefit from controlled degradation over days to months, so we see strong potential for applications like food packaging, and other short-lived consumer materials.”
Interesting Engineering, however, suggests this material could be used in longer-lasting plastic products like car parts, and so designed to last for decades.
Gu himself indicates that the implications go beyond a strategy to end the global plastics crisis. He believes the principle could enable innovations like timed drug-release capsules.
Some challenges remain. Gu cautions that currently, programmable plastic technology is less suited for plastics that need to remain stable for decades before breaking down. These include plastics used in construction materials.
Several other problems need solving before this type of plastic can be used commercially. One issue is that the liquid left over after the plastics deconstruct is composed of fragments of polymer chains. Gu and the research team stress that more tests must be conducted to ensure that these fragments aren’t toxic, and so can safely be released into nature. And to date, these materials have only been created and tested under laboratory conditions.
In addition, ultraviolet light is currently required to initiate the breakdown of this plastic, although ambient sunlight is enough. This means that until the researchers find ways to produce materials that can deconstruct in the dark, plastics that are buried or covered up in other ways are likely to endure in the environment almost indefinitely.
