A self-healing waterborne poly(urethane-urea) on reversible covalent interaction for textile breathable coating

The solvent-free self-healable waterborne poly(urethane-urea) (SH-WPU) product is environmentally friendly due to its lower volatile organic compounds emission during the coating process. This research revealed a strategy for breathable textile coating, that longer product life of SH-WPU coated fabric based on the self-healing dynamics that triggered by disulfide bond rearrangement upon temperature elevation (e.g., textile ironing). SH-WPU was synthesized with 4,4 '-methylenebis cyclohexyl isocyanate as hard segment, (poly(propylene oxide)-b-poly (ethylene oxide)-b-poly (propylene oxide) triblock copolymer as soft segment. 4,4'-Dithiodianiline (DTDA), and 2,2-bis(hydroxymethyl)butyric acid were used as the chain-extenders. The self-healing efficiency was tested by simulated ironing condition. The SH-WPU that contained 7.5 wt% of DTDA shown the highest recovery efficiency of stress at break by tensile test. The SH-WPU coated fabric showed excellent recovery with the DTDA concentration from 4.5 to 7.5 wt% by the water pressure resistance test by disulfide and hydrogen bond rearrangement at elevated temperature. The results indicated the promising potential of SH-WPU for breathable textile coating applications to not only overcome the damage under extreme weather conditions but also render the textile repairable by ironing.