Less than 9% of plastic gets recycled in the U.S. — most ends up in landfill or the environment. Truly compostable plastic would eliminate the microplastics that end up in the bodies of animals — and humans.
Most biodegradable plastics today are made of polylactic acid (PLA), a vegetable-based plastic material blended with cornstarch, or polycaprolactone (PCL), a biodegradable polyester. The new enzyme-activated compostable plastic could diminish microplastics pollution and holds great promise for plastics upcycling. The material can be broken down to its building blocks — small individual molecules called monomers — and then reformed into a new compostable plastic product. The new approach involves “nanoconfining” enzymes into plastics. Because enzymes are part of living systems, a safe place had to be carved into the plastic for enzymes to lie dormant until they’re called to action. The researchers embedded trace amounts of the commercial enzymes Burkholderia cepacian lipase (BC-lipase) and proteinase K within PLA and PCL plastic materials. They also added an enzyme protectant called four-monomer random heteropolymer (RHP) to help disperse the enzymes a few nanometers apart. Ordinary household tap water or standard soil composts converted the enzyme-embedded plastic material into its monomers and eliminated microplastics in just a few days or weeks.
Lawrence Berkeley National Laboratory and University of California, Berkeley
If not sorted properly, biodegradable plastic bags and containers can contaminate otherwise recyclable #1 and #2 plastics. Also, most biodegradable plastics take months to break down and they aren’t as strong as regular plastic.
The truly compostable plastic could be on the shelves soon. The researchers filed a patent application and a UC Berkeley startup — Intropic Materials — will further develop the new technology. The technology is available for licensing and collaboration.