Flexible, Robust, and Lightweight Multilayered Films Consisting of Alternating Poly(vinyl amine)/Nanofibrillated Cellulose and Porous Graphene Layers for Efficient Electromagnetic Interference Shielding

The next generation of advanced multifunctional electromagnetic interference (EMI) shielding materials is highly desired for its flexibility, ruggedness, light weight, and superior multifunctional shielding performance features. In particular, multilayered films comprising low-temperature modified porous graphene (LPG) and alternating poly(vinyl amine)/cellulose nanofibril (PCNF) layers were produced via an effective and simple alternating vacuum filtration method. Because of the mechanical frame effect of PCNF layers, the mechanical strength and toughness of the films reach 402.8 MPa and 1334.3 MJ·m^–3, respectively. The multiple reflection mechanism of the multilayer film enables EMI shielding effectiveness (SE) of 62.02 dB with a thickness of only 0.01 mm, with a specific SE of 11927 dB·cm²·g^–1. The multilayered films can withstand more than 3000 bending cycles while maintaining their shielding performance. Both an increase in layer spacing and the introduction of a porous structure can effectively improve the shielding performance. The multilayered PCNF@LPG films also show excellent Joule heating performance.