Indefinitely Recyclable Plastic

The world is alarmed about the use of non-recyclable plastics that do not break down easily and are the source of a lot of environmental pollution. In the United States, 30 billion plastic bottles are used by households every year out of which only a meager 57% are recycled. Can you imagine, around 700,000 plastic bottles in the US end up as litter in one day? At the current rate, this condition will worsen till about a staggering five truckloads of plastic dump per minute by 2050!

The circular economy is gaining growing attention as a potential way for our society to increase prosperity, cater scarcity towards toxic pollutants while reducing demands on finite raw materials. A new kind of plastic has been developed by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory in northern California that can be recycled indefinitely into new materials of any color, shape, or form. Ordinary plastic cannot be recycled repeatedly, because it degrades itself when it is recycled over time.

The scientists have now developed a chemical recycling method, which breaks the plastic down into its ‘building blocks’ that can then be purified and turned back into plastic. They identified two catalysts that can break down the polymers into constituent monomers with great efficiency of about 85 percent – at which point the monomers can be reused. The new material formed is called polydiketoenamine, or PDK. 

“Most plastics were never made to be recycled,” said lead author Peter Christensen, a postdoctoral researcher at Berkeley Laboratory’s Molecular Foundry. “But we have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective”. “With PDKs, the immutable bonds of conventional plastics are replaced with reversible bonds that allow the plastic to be recycled more effectively,” said Brett Helms, a staff scientist in Berkeley Lab’s Molecular Foundry and leader of the team that made this discovery.

Unlike the conventional plastics, the monomers of PDK plastic could be recovered and freed from any compounded additives by dipping the material in an inordinately acidic solution. This helps to break the bonds between the monomers and separate them from the chemical additives that give plastic its look and feel. Scientists believe that if facilities are designed for this purpose on a large scale then we would be able to successfully divert plastics from landfills and the ocean. The researchers at present are planning to develop PDK plastics with a vast range of thermal and mechanical properties for applications in diverse fields including textiles, 3D printing, and foams. 

This could be a game-changer in our quest to overcome a major source of pollution!

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