A sustainable, tough, flame-retardant polyurethane film from reversible chemistry and cyclotriphosphazene.
Some downstream application areas have put forward requirements for polyurethane (PU) films that can heal automatically, be flame-retardant, recyclable, and mechanically reinforced. But integrating these ideal capabilities into a single system is a huge challenge. Based on the reversible Diels-Alder (DA) reaction and cyclotriphosphazene, scientists have prepared a series of new self-healing, flame-retardant, recyclable and mechanically strong polyurethane films (PU-DA-x).
Use of cyclotriphosphazene shows extraordinary flame retardancy
Since the linear polyurethane chain containing side chain furan was effectively crosslinked by trimaleimide-terminated cyclotriphosphazene through the DA covalent bond, the tensile stress at break and Young's coefficient increased by 293% and 732%, respectively. The excellent self-healing ability of polyurethane films has been studied qualitatively and quantitatively based on reversible DA reactions. In addition, due to the addition of cyclotriphosphazene, synthetic polyurethane elastomers exhibit extraordinary flame retardancy. In addition, due to the retro-DA / DA process, PU-DA-x films have good recyclability.