Anthraquinone chromophore covalently bonded blocked waterborne polyurethanes: synthesis and application

Abstract

Dye-bonded blocked waterborne polyurethanes were developed to synchronously realize coloring and finishing of textiles and improve colorfastness using an anthraquinone chromophore and a methyl ethyl ketoxime blocking agent. The number-average molecular weight of the dye-bonded blocked polyurethane is 2303 g mol⁻¹ and the polydispersity is 1.06, indicating a narrow molecular weight distribution. The maximum absorption wavelengths do not shift after the monomolecular chromophores are bonded to the polyurethane. The self-colored polyurethanes provide better centrifugal stability and water solubility than the dye-mixed blocked polyurethanes. The dye-bonded blocked polyurethane offers good thermal stability below 100 °C and undertakes de-blocking at about 150 °C. The covalent bonding of the anthraquinone moiety with the polyurethane chain and temporary blocking of the terminal isocyanate groups are conducive to enhancing the tinting strength and colorfastness of the treated cotton fabrics. The self-colored blocked polyurethanes with good elasticity and toughness can improve the recovery angle of the treated cotton up to 120°, which can also endow the fabric with wrinkle resistance.