Working with a plastic called epoxy resin vitrimer, researchers at the University of Tokyo have created a new kind of plastic that is plastic-strong at room temperature, repairs itself when cut, breaks down into its recyclable ingredients when heated, and dissolves in seawater into edible material that can nourish marine life.
The plastic, dubbed VPR by its creators, also remembers past shapes. The researchers molded it in the shape of a bird, then flattened the sheet. When they heated it, the sheet resumed its bird shape.
Normally, epoxy resin vitrimer is brittle. The Japanese scientists found that adding a molecule called polyrotaxane makes it pliable. Polyrotaxane molecules look like tiny rings threaded on a skewer and make substances containing them more malleable.
As a result, when VPR is sliced with a blade, the cut heals in 60 seconds if the plastic is heated to 302°F (150°C). When molded to a shape and then crumpled or flattened, it resumes its previous shape.
When VPR is heated with a proprietary solvent, it lets go of its molecular bonds and falls apart into its original ingredients, which then can be recycled into more VPR or put to other uses.
VPR is five times more resistant to breaking than ordinary epoxy resin vitrimer, the developers reported. It repairs itself 15 times faster and breaks down for recycling 10 times faster, they claim.
Submerged for 30 days in seawater, a quarter of a VPR sheet dissolved into materials that can be eaten by underwater life with no ill effects, according to the developers.
TRENDPOST: Epoxy resins often are mixed with carbon and concrete in materials used to build bridges and other infrastructure. Adding VPR could make the structures self-healing under heat. VPR also can be stretched without losing its hardness, making it useful in making many molded shapes.
More broadly, this is another advance in the growing industry of alternative, less environmentally damaging plastics that eventually will replace today’s versions derived from petroleum.