Synthesis of bio-based fluorine-free branched polyurethane water repellent for cotton fabrics

In recent years, the growing awareness of environmental protection has led to significant attention being directed toward fluorine-free water-repellent agents in the textile industry. In this study, we developed an environmentally friendly approach to synthesize a bio-based fluorine-free branched polyurethane water-repellent agent specifically designed for cotton fabrics (CFs). The synthesis process involved three sequential steps: First, epoxy soybean oil polyol (DESO) was prepared through the reaction of soybean oil with dimeric acid. Subsequently, reactive waterborne polyurethane (RDPU) was synthesized by combining DESO with isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), and 2-hydroxyethyl acrylate (2-HEA). Finally, the bio-based fluorine-free branched polyurethane water repellent (HPU) was fabricated by utilizing RDPU as the primary component, with PET4A serving as the crosslinking agent and SA as the co-monomer. The results demonstrate that CFs treated with the HPU water-repellent agent performed outstandingly, achieving an exceptional water-repellency rating of 95 and a high water contact angle (WCA) of 145°, as well as remarkable surface stability. Furthermore, the softness of the finished CFs was objectively evaluated using an instrument. The results showed that the finished CFs possessed high softness, which was mainly attributed to the introduction of long alkyl chains.