Design of the reactive dyes containing large planar multi-conjugated systems and their application in non-aqueous dyeing

The development of pollution-free dyeing technology, including anhydrous dyeing and non-aqueous dyeing technologies, has always been an important way and research hot in energy conservation and emission reduction. Designing new structural dye molecules is the key to water-saving dyeing processes. Herein, three reactive dyes were designed and synthesized, which contained large planar multi-conjugated systems and multi-reactive groups. The designed reactive dyes are expected to have high affinity and high fixations in non-aqueous or small bath dyeing processes. The reactive dyes were applied in the decamethylcyclopentasiloxane (DMCS) reverse micelle dyeing for cotton fabric. High exhaustion rate of 99.35%, 98.10% and 98.80%, and fixation rate of 95.15%, 96.34% and 94.40% for three dyes, R1, R2 and R3, could be respectively obtained. The dyes can be fully utilized and had excellent dyeing performance, fastness and levelling properties under the revere micelle dyeing. The cotton fabric is like an oil-water separator in the dyeing process, where the dye micelles rapidly absorb and permeate into the cotton fibers. DMCS circulates around the fabric to transfer mass and energy. After dyeing, the solvent can be separated quickly and reused. The new reactive dyes containing large planar and multi-conjugated systems have potential application in green and sustainable dyeing technology with less wastewater and higher utilization.