Flexible spiral-like multilayer composite with Fe3O4@rGO/waterborne polyurethane-Ni@polyimide for enhancing electromagnetic shielding

Abstract

A well-designed multilayer composite with a unique spiral structure consisting of polyimide (PI) fabric and waterborne polyurethane (WPU) created by hot compression molding method for lightweight and flexible electromagnetic interference (EMI) shielding materials. Electroless Ni plating was employed to prepare the Ni@PI fabric and Fe3O4@rGO was evenly distributed throughout the WPU to provide conductivity and magnetism. Based on the reduced graphene oxide/WPU (rGO/WPU) composites, the addition of Fe3O4 nanoparticles improves the EMI shielding effectiveness (SE) of Fe3O4@rGO/WPU composites, especially the absorption efficiency. The continuous conductive network included in the Fe3O4@rGO/WPU-Ni@PI composite firmly locks electromagnetic wave as they enter the interior and provides more interfaces to increase multiple reflection losses, thus showing higher SE than traditional multilayer composites. The maximum SE value (36.8 dB) of the spiral structure composite with only 6.2 wt% Ni and 8.53 wt% Fe3O4@rGO loading is higher than that of conventional multilayer composites (27.0 dB), breaking through the bottleneck of high filler loading and low SE of conductive polymeric composites. Furthermore, after 1000 bending cycles, the composite with spiral structure retains significant EMI SE. The composite offers a wide range of applications, including electromagnetic protection for flexible electronic devices and the next generation of communication equipment.