Constructing <scp>SiAPP</scp>‐<scp>NH₂</scp>@<scp>MOFs</scp> Core‐Shell Structure Toward Hierarchical Composites With Excellent Flame Retardancy, Smoke Suppression, and Electromagnetic Interference Shielding

ABSTRACT Designing multifunctional composites with high flame retardancy and excellent electromagnetic shielding performance is of significant importance. In order to address the poor flame retardant and electromagnetic shielding performances of thermoplastic polyurethane (TPU) composites, in this work, the γ‐propyl‐trimethoxysilane (KH550) functionalized silicon microencapsulated ammonium polyphosphate (SiAPP‐NH 2 ) was synthesized using interface modulation technology. Then, SiAPP‐NH 2 was combined with a copper metal–organic framework (MOF‐Cu) through microencapsulation and electrostatic self‐assembly techniques to prepare microencapsulated flame retardants (SiAPP‐NH 2 @MOF‐Cu). Subsequently, TPU composites were prepared through melt blending of SiAPP‐NH 2 @MOF‐Cu with TPU material. The results showed that the interface interaction between SiAPP‐NH 2 @MOF‐Cu and the TPU matrix was significantly enhanced. Compared to pure TPU, TPU/5SAN@1MC composite exhibited decreases of 78.7%, 51.3%, 59.3%, and 58.7% in peak heat release rate, total heat release, total smoke release, and total carbon dioxide release, respectively. In addition, TPU/1SAN@1MC/rGO composite achieved an average shielding effectiveness of 13.82 dB in the X‐band, enabling its broad commercial application. This study offers a promising strategy for the fabrication of TPU composites with good flame retardant and electromagnetic shielding properties.