Investigation from molecular packing to application of azobenzene disperse dyes on polyester fabrics to realize waterless dyeing

Abstract

In this paper, three azobenzene disperse dyes with different substituents were selected to investigate the structure-performance relationship derived from molecular structure. Their visible absorption performances were evaluated in DMF and further analyzed using density functional theory (DFT) method. The dyeing properties of these disperse dyes on polyester fabrics in low pressure waterless dyeing system were discussed by comparing solubility, K/S value, levelling and color fastness. Additionally, the X-ray crystal diffraction analysis was used to investigate the relationship between dyeing properties, the nature of chemical structure and substituents therein. Carefully analysis showed that the dyeing uptake increased by 31.1% due to an introduction of cyano group in the diazo component. Meanwhile, the substituent acetoxethyl in coupling component further increased the dyeing uptake to 97.4%, which was attributed to low solubility. Crystal structures confirmed compact molecular arrangement results in low solubility and actually beneficial for the high dyeing uptake due to strong intermolecular interactions. Incorporating an understanding of the molecular packing analysis into the development of disperse dyes can improve the performance and promote the sustainable development of textile industry.