Core–shell structured Fe3O4@SnO2-reinforced self-healing polyurethane composite films with enhanced electromagnetic shielding performance

With the development of information technology, electromagnetic pollution has become a new source of pollution. Efficient EMI shielding materials are urgently needed to deal with this problem, and conductivity is the key to achieving efficient shielding. Impedance mismatch makes the composite shielding material obtain electromagnetic wave reflection dissipation ability, but excessive reflection loss will lead to secondary pollution of the environment. In this paper, polyaniline-modified graphene nanosheets (GNS@PANI) were used as conductive fillers, and tin oxide-coated ferric oxide (Fe 3 O 4 @SnO 2 ) with a shell–core structure was added to self-healing polyurethane (PU) as a magnetic conductive filler. The magnetic nanofiller with high permeability was used to improve the absorbing ability of the composite shielding material. When the addition amount of Fe 3 O 4 @SnO 2 is only 7 wt%, the composite film exhibits a high tensile strength of 5.22 MPa and an ultra-high self-healing efficiency of 89.66%, and the maximum EMI SE can reach 29 dB. Meanwhile, the SE A in the EMI SE is as high as 17 dB, and the SE R is only 12 dB, which is much lower than the SE A . To further enhance the electromagnetic wave absorption loss, we prepared a “sandwich” structure layered fabric using layer-by-layer assembly technology. This composite film has excellent electromagnetic absorption loss ability and has broad application prospects in the fields of medical devices, communication networks and flexible wearable electronics. Graphical abstract