Preparation of ecofriendly water-borne polyurethane elastomer with mechanical robustness and self-healable ability based on multi-dynamic interactions

Self-healing materials have attracted widespread attention owing to their capacity to extend the lifetime of materials and improve resource utilization. However, achieving superior mechanical performance and high self-healable capability simultaneously under moderate conditions remains a long-standing challenge. Integrating multiple dynamic interactions in waterborne polyurethane (WPU) systems can overcome the above-mentioned issue. Herein, environmentally friendly WPU systems containing multiple hydrogen bonds and boronic ester bonds in their polymer backbones were synthesized, where 2,6-diaminopyridine (DAP) and boric acid (BA) served as a dynamic chain extender and reversible cross-linking agent, respectively. The chain structure of the polymer was adjusted by controlling the ratio (DAP/BA) of hard segments, which could effectively meet the requirement of mechanical robustness and desirable self-healable efficiency. Benefiting from multiple dynamic interactions, the prepared WPU elastomer exhibited good mechanical properties, such as tensile strength (from 18.89 MPa to 30.78 MPa), elongation (about 900%) and toughness (from 54.82 MJ m −3 to 92.74 MJ m −3 ). Driven by water and heat, the IP-DAP 40 -BA 10 -WPU film cut in the middle exhibited good self-healing ability, with healing efficiencies of tensile stress of 90.74% and elongation of 91.29% after self-healing at 80 °C for 36 h. Meanwhile, the synthesized WPU elastomer exhibited good water resistance and thermal stability. This work presents a novel way to design robust self-healable materials, which will have wide promising applications in flexible electronics, smart coatings and adhesives. Environmentally friendly WPU with multiple hydrogen bonds and boronic ester bonds within its polymer backbone was synthesized. Benefiting from multiple dynamic interactions, the prepared WPU elastomer exhibited good mechanical properties and desirable self-healing ability.