A 'green' polymer could become even greener thanks to a process that eliminates the need for an environmentally damaging dyeing step.
Poly-lactic acid is a polyester manufactured from molecules derived from plants. The dyeing process typically uses large volumes of water and strong alkali, and generates sulphur-contaminated waste water. Patrick McGowan at the University of Leeds, UK, and his colleagues use an aluminium-based catalyst that polymerizes lactic acid or lactides and also carries the dye molecule. This allows the polymerization and dyeing steps to be combined into one, and obviates the need for additional harmful chemicals.
This 'DyeCat' method also reduces production costs and could be used by the textile industry, the authors say.