Self‐healing supramolecular waterborne polyurethane dispersions with quadruple hydrogen bonds in main chain

Abstract

AbstractA facile method for preparing supramolecular waterborne polyurethane (WPU) based on quadruple hydrogen bonds (4H‐WPU) is reported. Herein, 4H‐WPU with quadruple hydrogen bonds in main chain were synthesized by poly (1,4‐buthylene‐neopentylene adipate glycol) as soft segment, 2‐ureido‐4[1H]‐pyrimidinone (UPy) functionalized monomer, isophorone diisocyanate, 2,2‐Bis(hydroxymethyl)propionic acid (hydrophilic monomer), isophorondiamine, triethylamine (neutralizer), and monoethanolamine (blocking agent) as hard segment. The molecular weight of 4H‐WPU was controlled around 18,000 consistently. The properties of 4H‐WPU with different content of hydrophilic group, hard segment, and UPy units were characterized and the results could provide the reference for preparing supramolecular WPU with high mechanical and self‐healing performance while maintaining dispersion stability. The tensile strength of 4H‐WPU was 10 times of the blank sample. The healing time of scratched 4H‐WPU film was inversely proportional to the content of UPy‐ functionalized monomer and the shortest healing time is 2.5 hr at 80°C. Mechanical performance of healed films can be restored to more than 90%.