Heterogeneous Waterborne Polyurethane Composite with Alternating Electromagnetic Layers for Absorption-Dominated Electromagnetic Interference Shielding
Yujia Feng, Mengyao Li, Siqi Yang, Jian Wang
Abstract
Flexible waterborne polyurethane (WPU) electromagnetic interference (EMI) composites of heterogeneous alternating multilayer structure with conductive gradient were fabricated through the layer-by-layer stacking and hot-pressing methods. Combining the synergetic electromagnetic loss and interface polarization loss formed by the selective distribution of metallized chopped polyimide fiber (PI@Ni/Cu/Ni), reduced graphene oxide (rGO), and magnetic Fe 3 O 4 fillers, as well as multilevel electromagnetic wave propagation paths, the penetrating microwaves would undergo a particular “absorption–reflection–reabsorption” process in the composite. The asymmetric multilayer WPU composite with an absorption-dominated shielding feature exhibits a high EMI shielding effectiveness (SE) of 53.90 dB and an A value of 0.56. Moreover, the multilayer WPU composite maintains excellent integrity through repeating bending, long-time soaking, and burning tests. This work provides a viable strategy for the design of absorption-dominated EMI shielding material with controllable and stable performance that is befitting for next-generation advanced electronic products.