Tailoring biobased polythiourethane crosslinking networks with flame-retardancy and remote ultrafast infrared “welding” performance

A common approach for developing thermosetting polymers with self-healing performance is to introduce covalent adaptive networks into crosslinked systems. However, most self-healing polymers were conducted in “integral big materials”, which means “high energy consumption” and hard to carry out especially for those products with complex structures. In this work, thermosetting polythiourethane (PTU) dynamic networks with remote ultrafast infrared “welding” performance were designed. At first, biobased PTUs were synthesized by tailoring the crosslinking networks, which contain dynamic thiocarbamate bonds. Then, MXene, used for photothermal stimulation, was incorporated into the crosslinked PTU networks. The tensile strength and modulus of PTU ranged from 23.7 to 64.0 MPa and 17.4 MPa to 1.95 GPa, respectively, while the Tg could be tuned up to 83.4 °C. Moreover, due to the excellent photothermal conversion behavior of MXene and the reversibility of the dynamic thiocarbamate bonds, the PTU/MXene nanocomposites showed interesting remote and ultrafast infrared “welding” performance via the precise photothermal self-healing of the physical damage within 120 s. Meanwhile, the crosslinked PTU showed excellent intrinsic flame-retardant properties. This study may provide a novel strategy to facilitate the self-healing process for thermosetting polymers.