Flexible rGO/Fe₃O₄ NPs/polyurethane film with excellent electromagnetic properties

Large-area and flexible reduced graphene oxide (rGO)/Fe₃O₄ NPs/polyurethane (PU) composite films are fabricated by a facile solution-processable method. The monolayer assembly of Fe₃O₄ nanoparticles with a high particle-stacking density on the graphene oxide (GO) sheets is achieved by mixing two immiscible solutions of Fe₃O₄ nanoparticles in hexane and GO in dimethylformide (DMF) by a mild sonication. The x-ray diffraction and Raman spectrum confirm the reduced process of rGO by a simple thermal treatment. The permittivity value of the composite in a frequency range of 0.1 GHz-18 GHz increases with annealing temperature of GO increasing. For 5-wt% rGO/Fe₃O₄ NPs/PU, the maximum refection loss (RL) of over -35 dB appears at 4.5 GHz when the thickness of film increases to 5 mm. The rGO/Fe₃O₄ NPs/PU film, exhibiting good electromagnetic properties over GHz frequency range, could be a potential candidate as one of microwave absorption materials in flexible electronic devices.