Simple Approach for a Self-Healable and Stiff Polymer Network from Iminoboronate-Based Boroxine Chemistry

Despite offering robust mechanical properties, polymer networks suffer from a lack of recyclability, reshaping, and healability. Designing stiff and remendable polymer networks that can repair under mild conditions remains a challenge to extend their field of applications. Herein, we describe a simple approach to design a nonisocyanate-based polyurethane network featuring multiresponsiveness (to humidity and temperature) and outstanding healing properties, as obtained by combining iminoboronate and boroxine chemistry. In spite of the presence of abundant dynamic bonds, the network has a high stiffness (Young's modulus of 551 MPa) and tensile strength (11 MPa). C=N iminoboronate and B-O boroxine exchange reactions at high temperature enable efficient network recycling over multiple cycles without compromising its properties. Owing to these features, 3D objects could be designed and printed. The present approach provides excellent sustainable and high-performance substitution to conventional polyurethane networks requiring the use of toxic isocyanates.