Flexible rGO/Fe3O4 NPs/polyurethane film with excellent electromagnetic properties**Project supported by the National Natural Science Foundation of China (Grant Nos. 11274370, 51471185, and 11704288) and the National Key Research and Development Program of China (Grant Nos. 2016YFJC020013 and 2018FYA0305800).

Abstract

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.