Eco-friendly dual-chromophore functionalized polyvinylamine derivatives for clean and sustainable coloration of cotton fabric

To solve the challenges of dyeing wastewater pollution and the shortage of reactive green dyes with a single structure, the development of recoverable and recyclable green dye for cotton is urgent and crucial. In this work, a series of novel eco-friendly dual-chromophore functionalized polyvinylamine derivatives (GCPDs) were pre-pared by grafting yellow and blue chromophores onto polyvinylamine. The grafted polyvinylamine was used as pH-sensitive macromolecular colorants for clean and sustainable coloration of cotton fabric. The pH sensitivity, zeta potential, and dissociation behavior of the GCPDs were studied. The results revealed that GCPDs were sensible to pH, with an isoelectric point ranging from 8.5 to 10.0. When the pH of their solution was below 10, they formed aggregates due to strong electrostatic interactions. Compared with ordinary polyampholytes, the aggregation of GCPDs still occurred when the pH value of their solution deviated from the isoelectric point due to the presence of aromatic rings in their structure. The inner part of the cotton yarns colored with GCPDs was fixed with green color, indicating that GCPDs can be uniformly distributed in cotton fabric. Compared with conven-tional single-structure reactive green dyes, the color shade of the cotton dyed with GCPDs can be controlled by varying the types and molar ratios of the blue and yellow chromophores in their structure. CIELab values showed that a* value of the dyed cotton ranged from-26.065 to-12.548, while b* value shifted from 2.092 to 20.178. The fixation efficiency of the GCPDs on cotton was greater than 97% when a cross-linking agent was used. GCPDs can be recovered from dying residue, with a recovery rate of >98%. The cotton dyed with GCPDs exhibited rubbing and wash fastness grades of 3-4 and 5, respectively. The dyeing properties of recycled GCPDs were identical to those of the original GCPDs. Therefore, this study provides insight into the development of recyclable and reusable dyes for a clean and sustainable coloration of cotton fabric.