A polyurethane elastomer combining high strength and excellent self‐healing properties for waterproofing coatings

Self‐healing materials have not been able to solve the problem of the coexistence of mechanical strength and self‐healing function. Despite years of research, high‐strength self‐healing materials still require external factors to accelerate their self‐healing process. For this reason, in this study, two kinds of chain extenders were inserted into the hard segment to design the molecular structure of polyurethane. The introduction of two chain extenders not only provided multiple binding modes for hydrogen bond recombination, but also formed more types of hydrogen bonds. Based on the design, a polyurethane elastomer PUGI‐D3B2 with high strength and excellent self‐healing properties was synthesized. Data such as FTIR and 1H NMR spectra clearly demonstrate the successful synthesis of PUGI‐D3B2. The mechanical strength of PUGI‐D3B2 is 15.34 MPa, and its surface scratches can completely disappear after self‐healing at 60°C for 10 h，and 98.02% of the mechanical strength is restored after 12 h of heal. Therefore, combining the excellent self‐healing properties of PUGI‐D3B2, we prepared a multifunctional superhydrophobic material (SHN‐SiO2/PUGI‐D3B2). It can be used in a wide range of applications such as waterproof coatings, biomedicine and flexible electronics, which provides a new idea for the future direction of multifunctional materials. The self‐healing polyurethane (PUGI‐D3B2) constructed by two chain extenders selected in this study has excellent mechanical strength (15.34 MPa), good toughness (81.95 MJ m−3), and its surface scratches can completely disappear after self‐healing at 60°C for 10 h.