Simpler recycling process recovers pure raw materials from acrylic glass without solvents

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Large quantities of acrylic glass are used worldwide in a wide range of applications, from windowpanes and car taillights to furniture. The polymer is also known by the brand name Plexiglas.

All too often, acrylic glass still ends up as waste, even though it is well suited to recycling. ETH professor Athina Anastasaki, a materials scientist, has spent years working on ways to efficiently break down acrylic glass into its constituent building blocks for reuse. In previous studies, her team showed that this process, known as depolymerization, was possible in principle, but only under specific conditions.

For example, ETH researchers previously had to chemically modify the polymer chains to introduce "weak links." Other approaches required large quantities of solvents or catalysts, or UV light, to initiate or sustain depolymerization. The ETH professor and her team have now developed a new, simpler approach to recycling acrylic glass polymers. They have published their findings in the journal Nature Chemistry.

Using the new method, the researchers can break the polymer down almost entirely into its constituent building blocks, known as monomers. The monomer yield can be as high as 98%. The recovered material is also pure, even when the starting material contains dyes or impurities.

The recovered monomers can be used to produce new polymers of the same quality as those produced during initial processing. The process also requires significantly less energy than other methods. Depolymerization begins at just over 200 degrees Celsius (392°F), compared with the minimum of 400 degrees Celsius (752°F) previously required.

Moreover, the process uses no solvents. "What makes our new approach so exciting is its simplicity," says Richard Whitfield, lead author of the study and a former research associate in Anastasaki's group. At the heart of the new method is a single chemical compound belonging to a class of substances known as N-hydroxyimides.