Sustainable Polyurethane Networks with High Self‐Healing and Mechanical Properties Based on Dual Dynamic Covalent Bonds

Abstract Hydroxy‐terminated polybutadiene (HTPB) based polyurethanes (PU) networks are broadly applied in industry and aviation, however, their nonrecyclability leads to the waste of petroleum. In this work, a series of novel self‐healing, weldable, and recyclable HTPB‐based PU networks with dual reversible covalent bonds are fabricated by one‐pot polycondensation. To shorten the relaxation time, dual reversible covalent bonds (disulfide bonds and boronic ester bonds) are incorporated into the HTPB‐based PU networks. Meanwhile, to promote tensile strength, the rigid isocyanate and cross‐link agent are introduced into the networks. Obtained HTPB‐based PU network structures are characterized by FTIR, Raman, and DMA measurements. Obtained HHMB‐4‐20 network shows the best mechanical properties (tensile strength = 6.97 MPa, elongation at break = 302 %), and the mechanical properties almost can be recovered after welding/reprocessing by hot pressing. To satisfy the demands of industrial sustainability, the synthesis of PU networks with capabilities of reprocessing, self‐healing, and welding is a feasible approach.