Highly effective core-shell CNF/HGM@CS/MXene electromagnetic interference composite films with superior flame retardancy

In view of the prominent issues in compatibility, sustainability, and performance stability of existing polymer-based electromagnetic interference (EMI) shielding films, this work proposes a strategy for preparation of a series of novel flame retardant and EMI shielding composite films, which were fabricated using cellulose nanofibers (CNF)/MXene/chitosan-modified hollow glass microspheres (HGM@CS) as the matrix, and flame-retardant thermoplastic polyurethane (TPU/APP-NH 2 @LDH) as the encapsulation shell. The results demonstrated that the CNF/MXene/HGM@CS/TPU/APP-NH 2 @LDH (CM x HTA) composite films exhibited good hydrophobicity (with a water contact angle of 100.6°), and superior flame retardancy. The peak heat release rate and total heat release of as-prepared CM 2 HTA composite film were decreased by 53.0% and 52.2%, respectively, compared with those of pure CNF/TPU composite film. The improvement in flame-retardant performance is attributed to the synergistic mechanism of APP-NH 2 @LDH, HGM@CS, and MXene in both the gas phase and the condensed phase. Due to the electromagnetic shielding mechanism of “surface reflection-internal absorption”, the values of EMI shielding effectiveness of the CM 3 HTA composite film reached 43.5 dB and 56.7 dB in the X-band and K-band, respectively, far exceeding the requirements for commercial shielding materials (≥20 dB). This study provides a new approach for developing high-performance, multifunctional, and environmentally friendly electromagnetic shielding composites in the application of electronic protection, smart packaging and wearable devices, etc.