ETH researchers achieve breakthrough in Plexiglas recycling

(CONNECT) ETH researchers from the Laboratory for Polymer Materials have laid the foundation for plastics such as Plexiglas to be almost completely broken down into their building blocks in a simple way and then reused. This opens up new ways of specifically breaking down the previously chemically inaccessible carbon chains of plastics. In a report, the ETH describes this as a breakthrough in Plexiglas recycling.

"Our process is very simple," ETH professor Athina Anastasaki is quoted as saying. "We only need a chlorine-containing solvent, we have to heat the dissolved recycling mixture moderately to 90 to 150 degrees Celsius and can then start the degradation reaction in a targeted manner with the help of visible or UV light." Her group was actually looking for specific catalysts that specifically promote the splitting of the polymer into monomers. "But in a control experiment, we were surprised to discover that the catalyst wasn't necessary at all."

On closer examination of the cleavage reaction, the group discovered a surprising mechanism. With the support of other ETH scientists, they were able to identify the chemically active particle in the reaction: a chlorine radical.

It was unexpected that long-wave light can break the bond between the chlorine and the solvent molecule. "This", according to the ETH, "occurs through an almost esoteric photochemical phenomenon in which a very small proportion of the solvent molecules absorb UV light with a long wavelength". Because chlorinated chemical compounds are harmful to the environment, the reactions are now to be modified so that they also work without them. ce/mm