Less than 10% of discarded plastic is recycled. This is one of the major reasons that plastic waste is such a threat to the environment. There are many challenges to recycling plastics. For one thing, there are many different types of plastic and if they are melted together, they tend to phase-separate like oil and water and the resultant substance is structurally weak. Sorting plastics by type is not a simple task. More generally, it is very difficult to produce plastic with its original properties from recycled feedstock. So recycled plastics generally end up being useful in only more limited applications.
Chemists at Colorado State University have recently published a paper in the journal Science that announced a major step toward waste-free, sustainable materials that could provide important advantages over conventional plastics. They have discovered a polymer with many of the desirable characteristic of plastic – light weight, heat resistance, strength, and durability – but with the ability to be fully converted back to its original small-molecule state for complete chemical recyclability. Furthermore, this can be accomplished without the use of toxic chemicals or intensive laboratory procedures.
The new monomer material can be polymerized – turned into the massive molecules that characterize plastic – with environmentally friendly and industrially practical techniques. The resultant material has all the properties desired in plastic. But unlike ordinary plastic, the new material can be recycled back to the monomer state and then can be repolymerized. It is a true circular materials cycle.
Patents are pending on the material and processes and there is much work to be done to scale it up. But a true chemically recyclable polymer could be just what the world needs.
Photo courtesy of Bill Cotton/Colorado State University.