Microcrack self‐healing capability of waterborne polyurethane/polyacrylate composites with dynamic disulfide bond

Abstract In this paper, a series of self‐healing waterborne polyurethane/polyacrylate composites (SWPUA) with different disulfide content on the main chain were synthesized. The SWPUAs were synthesized from isophorone diisocyanate, dimethylolpropionic acid, polyether diol and bis(2‐hydroxyethyl) disulfide (HEDS). The structure of the products was characterized by IR and Raman spectra. The effects of different content of HEDS on dispersion stability, mechanical property and self‐healing properties (including tensile strength and breaking elongation) of SWPUAs were studied. The results showed that all the prepared SWPUAs have excellent dispersion stability, thermal stability, self‐healing efficiency and certain hydrophobic capacity. Thereinto, SWPUA‐1 and SWPUA‐2 products with HEDS content of 0.0025 mol and 0.0050 mol have the best repair efficiency. They can recover 101.03% and 102.18%, respectively, after 3 h of repair at 75°C. In addition, SWPUA‐1 has the highest repeatedly repair efficiency of 91% for tensile strength but 75% for breaking elongation because of the influence of physical entanglement and chain link.