ETH Zurich method depolymerizes acrylic glass at lower heat without solvents

What the method does

The process belongs to chemical recycling: acrylic glass, also known by the brand name Plexiglas, is broken into its constituent monomers for reuse. Earlier approaches from the same group required chemically modified polymer chains, large amounts of solvents or catalysts, or UV light. The new method instead relies on one inexpensive, commercially available compound from the N-hydroxyimide class, which attacks the polymer chains and releases the monomers. The recovered monomers can make new polymers of the same quality as those from initial processing, according to the university.

The work was published in Nature Chemistry. Richard Whitfield, a former research associate in Athina Anastasaki's group, is lead author; Anastasaki is an ETH professor of materials science.

Why it might matter to industry

The energy and purity numbers are the central claims. Depolymerization starts at just over 200 degrees Celsius, against the 400 degrees or more typical of pyrolysis, which ETH says often leaves monomers with impurity levels up to 3%. Because no solvents are used and existing infrastructure and standard processes could be reused, the researchers argue industry could adopt the method without costly equipment changes. ETH Zurich has filed a patent application and is seeking licensees.

Limits and next steps

The method works only with acrylic glass. The team's next steps are to scale the process up and to understand the reaction mechanisms in detail, then develop substances intended to speed breakdown and raise yield. Anastasaki says the group will try to apply the same principle to polystyrene.