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This plant-based plastic is inspired by the chemistry of spider silk


It’s both durable and strong, but also easily breaks down in nature—unlike some other “compostable” plastics.

Some plastic waste is invisible: Shampoo, laundry detergent, and other common products often use tiny capsules made of microplastic as an ingredient. Those capsules then wash down the drain and can pollute waterways. A startup spun out of the University of Cambridge wants to replace those capsules—and other plastics that are hard or impossible to recycle—with a plant-based material that can easily dissolve.

The new material mimics spider silk, one of the strongest natural materials, on a molecular level. “The molecules in spider silk are bound together very tightly even though the interactions themselves are very weak,” says Tuomas Knowles, a chemistry professor at the University of Cambridge and one of the authors of a new paper in Nature Communications about the research. “The way that nature manages to do that is by arranging them in a regular pattern.”

The scientists developed a new process to dissolve plant-based protein in the right conditions so it forms into a similar structure. The process uses little energy, and can use sustainable ingredients; in the study, the team used soy protein isolate, a by-product of making soybean oil. Other plant-based materials that often end up as waste could also be used.

Unlike other bioplastics, it doesn’t need to be modified chemically for the materials to hold together and be durable, but it also dissolves much more easily. “We don’t modify the molecule itself in any way,” Knowles says. “We just reassemble them in totally different arrangements. And it turns out that if you do that in a smart way, you end up with these really strong materials, which are still nevertheless totally degradable, exactly the same way as a spider’s web is degradable.”

That means the material can break down in a home compost bin, unlike many other compostable plastics that require specific conditions only found at industrial composting facilities. Though the team hasn’t yet tested how it would break down in the ocean, they expect that it would also degrade easily in water, unlike some other compostable plastics that are only likely to break down when the water is hot. “In some sense, from a degradability point of view, it’s no different from taking a plant and putting it in the ocean,” says Knowles.

Xampla, the startup spun out from the research, plans to release its first products later this year. Though the technology could be used to make different types of plastic, they’re focused on the areas that can have the biggest impact first, including the microplastics in laundry detergent. “If you think plastic bags are difficult to collect from the environment, imagine trying to collect these bits of plastic which are too small to see by the naked eye,” Knowles says. “Once they’re in the ecosystem, they’re there for thousands or tens of thousands of years.”

Source: https://www.fastcompany.com/90644935/this-plant-based-plastic-is-inspired-by-the-chemistry-spider-silk

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