Thermoplastic polyurethane foams derived from cellulose nanofibril/carbon nanotube/(Fe/C) aerogels for efficient electromagnetic interference shielding

The electromagnetic interference (EMI) shielding performance of a material can be enhanced by combining carbon and magnetic components to make the material simultaneously conductive and magnetic. In this work, a series of cellulose nanofibril (CNF)/carbon nanotube (CNT)/(Fe/C)/thermoplastic polyurethane (TPU) foams are fabricated by preforming CNF/CNT/(Fe/C) aerogels followed by combing TPU to improve the mechanical property, where Fe/C is derived from Prussian blue (PB, Fe4[Fe(CN)6]3) after pyrolysis. Consequently, the obtained aerogels and foams display electrical conductivity and magnetism. The CNF/CNT/(Fe/C)/TPU foam reaches a high EMI shielding effectiveness value of 42.2 dB at a thickness of 2 mm when the mass ratio of PB and CNT is 5:1 and the pyrolysis temperature is 650 ℃. Furthermore, the CNF/CNT/(Fe/C)/TPU foam exhibits compression resilience and hydrophobicity. This study is expected to provide a feasible strategy to acquire absorption-dominated EMI shielding materials by imparting conductivity, magnetism and porous structures to the material.