Pearl-inspired self-extinguishing, thermal-conductive, and robust thermoplastic polyurethane composite by strengthening inter-layer packing

Fabricating thermoplastic polyurethanes (TPU) that exhibit self-extinguishing properties alongside strong mechanical characteristics and high thermal conductivity represents a challenging yet imperative endeavor within both scientific research and industrial applications. Enhancing the thermal conductivity of composites necessitates meticulous attention to surface treatment and the orientation of chemically inert hexagonal boron nitride sheets (BNNS). In this study, BNNS are treated by Strengthening inter-layer packing, which enriches the mechanical enhancement mechanism of the "brick-mortar" structure of natural pearl layers. The treatments use copper hydroxyethylidene diphosphonate and melamine hydroxyethylidene diphosphonate, which have a synergistic flame retardancy. Self-extinguishing TPU films with strong mechanical strength (57 MPa) and high thermal conductivity (9.12 W m−1 K−1) are produced when the functional particles are oriented to create multiple synergistic effects with the TPU simultaneously. Furthermore, when comparing CP0.02/MP@BNNS-TPU composite film to BNNS-TPU film, the limiting oxygen index of TPU composites increased to 30.2 %, and there was a significant decrease in both the peak and total heat releases (77.2 % and 80.6 %, respectively), meeting the UL-94 V-0 standard. This work offers a fresh method for creating self-extinguishing materials with high heat conductivity and robust mechanical characteristics.