Constructing of Dyes Suitable for Eco-friendly Dyeing Wool Fibers in Supercritical Carbon Dioxide

Compared with traditional water dyeing, supercritical carbon dioxide (scCO2) dyeing is more environmentally benign. scCO2 is widely used as a green solvent in dyeing synthetic fibers. However, studies involving dyeing natural fibers in scCO2 are scarce. The commonly used methods result in corrosion of the dyeing equipment. Thus, the development of new special dyes suitable for scCO2 dyeing is necessary; in addition, insight into the dyeing mechanism is important in promoting the design and synthesis of dyes for wool fibers in scCO2. On the basis of our previous work, a possible dyeing mechanism in which the dyes exhibit hydrophobic interaction with keratins is proposed. The N═N bond twisting in azo dyes promotes the dyes embedding into the spaces of the alpha helices in proteins. According to the proposed mechanism, two new azo disperse dyes (azo thiazole-N(CH3)2 and azo thiazole-OCH3) were synthesized; these dyes enable the dyeing of wool fibers in scCO2. Meanwhile, the introduction of a succinimidyl est...