Plastic; it’s a problem.
As children of the Oil Age we have inherited a heap of issues from the generations that preceded us, and we’ve grown up feeding into these problems too. Advancements in fuel technology and manufacturing over the past century have had serious environmental implications. Have you seen the state of the world’s oceans?
Thankfully there are teams of scientists committed to countering the damage we have done to the planet, and a significant chemical breakthrough in the composition of plastic could be about to revolutionise how we use the material.
What is closed-loop recycling you ask? It has been referred to as ‘the Holy Grail’ of recycling, and would mean plastic could be repurposed time and time again for various uses, which is obviously preferable to single use plastic being sent to landfill, destroyed, or finding its way into the ocean.
Lead author Peter Christensen, a postdoctoral researcher at Berkeley Lab’s Molecular Foundry, said in a statement:
Most plastics were never made to be recycled, but we have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective.
I hope you speak science, because here comes a whole load of it.
As per the study’s abstract:
Recycled plastics are low-value commodities due to residual impurities and the degradation of polymer properties with each cycle of re-use. Plastics that undergo reversible polymerization allow high-value monomers to be recovered and re-manufactured into pristine materials, which should incentivize recycling in closed-loop life cycles. However, monomer recovery is often costly, incompatible with complex mixtures and energy-intensive. Here, we show that next-generation plastics—polymerized using dynamic covalent diketoenamine bonds—allow the recovery of monomers from common additives, even in mixed waste streams.
Poly(diketoenamine)s ‘click’ together from a wide variety of triketones and aromatic or aliphatic amines, yielding only water as a by-product. Recovered monomers can be re-manufactured into the same polymer formulation, without loss of performance, as well as other polymer formulations with differentiated properties.
The ease with which poly(diketoenamine)s can be manufactured, used, recycled and re-used—without losing value—points to new directions in designing sustainable polymers with minimal environmental impact.
Did you get that? Yeah I had to read it twice too. In essence carbon-containing monomers bind chemically in the current process of plastic manufacture.
This in turn means it is hard to predict what properties are passed on in recycled plastics, limiting their usability as most products require a considerable degree of predictability and integrity for their desired use.
Poly(diketoenamine), or PDK, prevents this issue of unpredictability as it can be degraded in an acid bath, reducing to its ‘molecular building blocks’.
Brett Helms, a staff scientist at the Berkeley lab, explained:
With PDKs, the immutable bonds of conventional plastics are replaced with reversible bonds that allow the plastic to be recycled more effectively.
We’re interested in the chemistry that redirects plastic lifecycles from linear to circular. We see an opportunity to make a difference for where there are no recycling options.
PDKs have only been achieved in a lab setting thus far, but forget necessity being the mother of invention, it’s already here. Necessity will hopefully prove the mother of adoption, and the team at Berkeley’s breakthrough should lead to a brighter future where 100 per cent recyclable plastics are the norm.
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