Eco-friendly curcumin-based dyes for supercritical carbon dioxide natural fabric dyeing

An obvious limitation of curcumin is its inability to achieve a deep color depth, which is caused by curcumin's low supercritical carbon dioxide solubility. In this study, alkyl groups (ethyl, butyl, hexyl or octyl) were introduced to curcumin to achieve better solubility and dyeing ability. The results showed that both the solubility and dyeing ability of curcumin increased after alkyl grafting. The best dyeing ability was achieved by using butyl curcumin to dye silk in the presence of dimethylsulfoxide (DMSO). This phenomenon is closely related not only to the high solubility of butyl curcumin but also to the increase in the silk specific surface area, resulting from the synergistic effects of supercritical carbon dioxide and dimethylsulfoxide.