Ultrafast catalytic charring towards anti-flammable thermoplastic polyurethane with superior dripping suppression and fire protection

Abstract

The realization of exceptional anti-flammability and fire protection with a weakened dripping of thermoplastic polyurethane (TPU) at a low loading of fire retardants remains a spiny dilemma. We herein propose a unique proof of concept of an ultrafast catalytic charring mode for immobilizing flowing drops and “killing” flame. Following up the idea, a lamella-on-sphere assembly (MAPP@Salen-Cu) was validated via anchoring Salen-Cu lamellas on a silanized ammonia polyphosphate spheres. A low 5 wt% MAPP@Salen-Cu imparted TPU with UL-94V-0 rating and a suppressed dripping. An exceptionally strong fire protection was revealed by temperature detection and mechanical response of fire chars. A featuring ex-situ UL-94 analysis witnessed an ultrafast formation of compact carbon, elucidated by a condensed-phase radical scavenging and a low-temperature intensive catalysis. Additionally, the ultrafast catalytic charring coupled with a typical esterification-crosslinking intumescence jointly contributed to fire-safe, dripping-suppression and fire-protective performances of TPU. Prospectively, an ultrafast catalytic charring mechanism exploits an innovative and pioneering road towards a highly efficient fire safety.