First steps towards a new type of infinitely recyclable plastic

Every year, we disperse 100 million tons of plastic in nature. And if for some polymers, such as Pet And PVCthe solution lies in recycling, for a class of plastic materials known as thermosetting polymers reuse is not yet possible. A research just presented on Nature ChemistryHowever, it could have the solution: a chemical technique to decompose and reassemble these materials indefinitely, without modifying their physical and chemical properties in any way.

Thermosetting plastics are materials with a high resistance to thermal and mechanical stress, and for this reason they are used in fields ranging from the aerospace industry, to microelectronics, up to the production of kitchen utensils. However, the characteristics that make them attractive also complicate their recycling: once they have been given a shape and made to harden, it is no longer possible to melt them to reshape them, without definitively destroying the material.

Exactly the opposite of what happens with i thermoplastic polymers, which once collected can be melted and reworked to obtain new objects. Traditional recycling methods involve the mechanical shredding of waste, the use of heat or bacterial enzymes to dissolve the waste and obtain the material to be reused. In their study, however, researchers from the University of Colorado at Boulder describe a different technique, based on chemical processes that allow you to break the bonds between the individual units that make up polymers – that is, the monomers – and then create new ones, to obtain a thermosetting polymer that can be modeled and then made to harden, to create a new object. Not only that: with the same method it is in fact possible to create new polymers with different physical and chemical properties, by binding the monomers together like Lego bricks.

In the study, the researchers used a type of resins called cyanate esters, used in the production of printed circuits and in the aerospace sector, demonstrating that they can break down the material into its starting monomers, and then be able to use them to create a new type of plastics. never before obtained thermosets, defined in English as alkyl-polycyanurate thermosets, with extremely interesting physical properties, and completely recyclable indefinitely using their new technique. A success that researchers believe could pave the way for the recycling of many other types of thermosetting polymers, as well as the development of new types of plastics that are unknown today.

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“We are really thinking outside the box, to find different ways to break the chemical bonds of polymers,” he explains Wei Zhang, a chemistry professor at the University of Colorado at Boulder who coordinated the new research. “Our chemical method it can help create new technologies and materials, and also be used to solve the current plastics crisis. The future of plastics not only needs new polymers, but also the ability to convert, recycle and reuse old ones. ”