Covalent polyester colouration by in situ chromophore creation.

The permanent colouration of a polyester by straightforward azo coupling is disclosed. Uniquely, the chromophore is created only upon successful polymer modification with a non-coloured molecule (in situcolouration), which confirms successful polymer adaptation and ensures that coloured waste is not produced. The method of colouration, which may feasibly be applied for the coloration of a wide-range of step-growth polyesters, yielded a polymer capable of preventing indigo deposition onto a range of fabrics, offering potential use within advanced detergent formulations.