Plastic is useful and ubiquitous – but that’s not always a good combination. The vast majority of plastic waste can’t be recycled, meaning it ends up in landfills at best or the ocean at worst. To help curb the problem, researchers at Berkeley Lab have designed a recyclable plastic – called poly(diketoenamine) or PDK, 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 over and over again without loss of performance or quality.
The most basic building blocks of conventional plastics are molecules called monomers, which are tightly bound together into polymers and mixed with other chemical additives. Normally those bonds are hard to break, but the monomers in PDK plastic are designed to come apart more easily, allowing them to later be rebuilt into something new. The team tested various mixtures of the material, and then demonstrated that the whole cycle can work as hoped.
The PDK plastics were effectively broken down in acid, and the resulting monomers were then rebuilt into new plastics. The colors and other properties of the old products didn’t affect the new ones. The team says the plastics could also be “upcycled” into higher quality products by adding new chemicals.
