Synthesis of an amino‐terminated hyperbranched polymer and its application in reactive dyeing on cotton as a salt‐free dyeing auxiliary

A water‐soluble amino‐terminated hyperbranched polymer was synthesised from methyl acrylate and diethylene triamine by melt polycondensation. Its molecular weight and possible structure were characterised by gel permeation chromatography, Fourier transform infrared spectrophotometry and nuclear magnetic resonance spectroscopy. The zeta potential of cotton fabrics treated with the aqueous solution of the amino‐terminated hyperbranched polymer (6 g dm−3) in the presence of citric acid (2 g dm−3) and sodium hypophosphite (3 g dm−3) of the liquid phase is positive at pHs lower than 7.5. Dyed with reactive dyes, the treated cotton fabric displayed a markedly enhanced colour strength, even when dyeing had been carried out in the absence of the electrolyte. The washing fastness, rubbing fastness and levelling properties of the dyed, treated cotton fabrics were also good compared with that obtained by conventional dyeing. The dyeing behaviour of Reactive Brilliant Yellow A‐4GLN on treated cotton fabric was examined and found to follow a Langmuir‐type adsorption curve. It is concluded that the amino‐terminated hyperbranched polymer can be used as a salt‐free auxiliary in reactive dyeing on cotton.