Flexible and flame-retarding phosphorylated MXene/polypropylene composites for efficient electromagnetic interference shielding

Flame-retardant composites with high electromagnetic interference (EMI) shielding performance are desirable for electronic device packaging. Despite great potential of MXene for high EMI, it still remains a great challenge to develop high-performance flame-retardant polymer/MXene composites with excellent EMI shielding effectiveness because of the poor oxidative stability of MXene. Herein, phosphorylated MXene/polypropylene (PP) composites are prepared by coating phosphorylated MXene on PP fabric followed by spraying polyethylenimine (PEI) and hot-pressing. The phosphorylated MXene proves to be more durable against oxidation than pure MXene due to the protection effect of polyphosphates. Upon hot-pressing, melted PP fibers are fused together at their contact points and thus as-prepared composites are bi-continuous with two interpenetrating phases. The composites show significantly improved thermal stability and flame retardancy relative to pure PP, with a low total heat release (THR) of 3.7 kJ/g and a heat release rate (HRR) of 50.0 W/g, which are reduced by 78% and 87%, respectively. In addition, the composites exhibit a high electrical conductivity of ∼36,700 S/m and an EMI shielding performance of ∼90 dB over the whole frequency range of 8–12 GHz with a thickness of ∼400 μm. The as-developed PP/MXene composites hold great promise for reliable protection of next-generation electronic devices working in complex environments.