In a perfect world, plastic will never be on a journey to a landfill – it's a vision that we aspire to realize for decades. Unfortunately, some plastics are simply not recyclable easily, as well as others, limiting how well we can use them in new products. But the new kind of plastic can help to change it all.
Researchers at the US National Laboratory Lawrence Berkeley, the US Department of Energy, have designed a new type of plastic polymer that can be broken down and rebuilt again with the simplicity of the molecular Lego brick.
"Most plastics have never been made to recycle," says chemist Peter Christensen.
"But we discovered a new way to collect plastic, which should be considered for recycling from a molecular perspective."
All plastics are more or less repetitive units – or monomers – of compounds derived from an organic substance such as petroleum.
That sequence of molecules can be mixed with a wide range of chemicals, giving plastic versatile properties that allow us to use for almost nothing from garment bags, straw and furniture.
The perpetual confusion of consumers everywhere, some of these plastics can be divided into components and relatively recycled. But not all. We could throw our polyethylene terephthalate (PET) bottles to drink in the recycling tank, but not a heavy thermistor plastic toy or dishware.
Many plastics suffer from those additives that fasten to the molecular chains to dye, soften or solidify, making unpredictable chaos of ingredients to turn into a durable product that we can easily afford.
Researchers have made some progress in redesigning thermosetting plastics to be recyclable, but in order to solve our growing plastic crisis, we need to make the process more efficient and simpler, and the new type of plastics developed in the Berkeley Laboratory has the potential to meet such requirements.
Its building block is a monomer called diketoenamine: a compound formed by sticking to a trikeketon in an amine.
The condensation of these units in a long range is a plastic called poly (dicetoenoin) – or PDK – and the connections can be easily dissolved, using nothing more than a 12-hour soak in a strong acid bath.
"With PDK, the invariable connections of conventional plastics are replaced by reversible bonds that enable more efficient recycling of plastics," says chemist and team leader Bret Helms.
With easy breaking of the polymer, the basic units of plastic can be separated from any additions over and over again in what is described as a cycle of a closed cycle.
The researchers tested the recovery process by contamination of PDK and acid solutions with other substances, including fiberglass and flame-chemicals, revealing that aditives had little impact on their dicetoemeanic harvest.
The end result is a plastic ingredient that can release all colors or enhancing agents in a few easy steps that need to be returned to another product.
"We are interested in chemistry that redirects plastic life cycles from linear to circular," said Helms.
"We see an opportunity to distinguish where there are no recycling options."
Currently, most of our recycling efforts are abysmal. While some countries are doing their best, countries like the United States almost fail to recycle a quarter of their PET waste.
Governments can always do little to carry out an action, but at the end of the day, talks about money. Earlier this year, researchers showed how they could turn plastic into a much more lucrative resource: fuel.
All the methods that we can find to be easy to recycle for the consumer and to like the manufacturer, it's worth exploring.
We are certainly a long way from sending our PDK forks to an acid tank in our local recycling plant. Further research is needed to test the suitability of polymer for different applications. No one wants a flexible plastic knife or a fragile packing bag, no matter how much it is recycled.
But, regardless of the results, this is what looks like the future of plastic – and we need it urgently.
This study was published in Chemistry of Nature.