Scientists in Vienna have developed a low-cost solvent that separates polycotton blends into reusable cotton and polyester – potentially reshaping textile recycling economics.
Recycling polycotton, the industry’s most ubiquitous blend, has long proven stubborn. Polyester and cotton are tightly interlocked, making separation costly, inefficient or chemically destructive. A new approach from the Vienna University of Technology may change that.
Researchers led by PhD student Nika Depope and Dr Andreas Bartl have created a “deep eutectic solvent” made from menthol and benzoic acid. When heated to 216°C, the mixture dissolves polyester within five minutes while leaving cotton fibres intact. Upon cooling, polyester precipitates and can be recovered; cotton can simply be washed and reused.
Early trials recovered 100% of the cotton and 97% of the polyester, with neither fibre chemically altered. Both materials retain their performance properties, allowing re-spinning and reprocessing without downcycling.
If scaled, the technology could address one of fashion’s biggest waste challenges: blends that are economical to produce but nearly impossible to recycle. A low-toxicity, inexpensive solvent system could reduce dependence on virgin polyester and ease pressure on cotton supply, while making textile-to-textile recycling more economically viable. The method’s simplicity also positions it as a possible complement – or competitor – to more capital-intensive depolymerisation technologies.
The research team is now working to lower the required temperature to make industrial adoption more feasible. If energy demands fall and process economics improve, the solvent could become a commercially relevant solution for global mills and recyclers struggling to handle blended-fibre waste.
