Microstructure engineering of core-shell flame retardants: SiO 2 and MXene encapsulated ammonium polyphosphate for fire-safe thermoplastic polyurethane

Microstructure manipulation represents a fundamental strategy for enhancing material properties. Herein, a new-type flame-resistant material with core-shell architecture (APP@PEI@SiO2@MXene) is prepared by iterative deposition of self-assembled monolayers, enabling microstructural control of ammonium polyphosphate (APP) via sequential coating with polyethyleneimine (PEI), SiO2, and MXene. Then the flame retardants were incorporated into thermoplastic polyurethane (TPU) at a loading of 15 wt.%, t