Porous Core-Shell PU Composite Membrane with a AgNW Conductive Network for Electromagnetic Shielding

To date, it has been challenging for electromagnetic interference (EMI) shielding materials undergoing external mechanical stimuli containing stretching, bending, or large deformations to maintain excellent EMI shielding effectiveness and long-term structural stability. At the same time, EMI shielding materials require high shielding effectiveness and low reflection, reducing secondary pollution of electromagnetic waves. Herein, porous core-shell polyurethane (PU) fibers featuring a rich porous microstructure are prepared by coaxial wet spinning, with elastic elongation capacity exceeding 1500%. This work explores a porous core-shell PU fiber substrate by loading silver nanowires (AgNWs), forming an interconnected conductive network in the PU fiber matrix. The resultant composite is stable, successfully achieved through the thermal adhesion of PU nanofibers between the AgNW functional layer and the PU substrate layer. The composite (500 mg of PU fiber substrate) loading of 36 mg of AgNWs results in the EMI shielding efficiency of 39.41 dB. While it is stretched under 10% deformation, its EMI shielding efficiency exceeds 23.14 dB. Even if electromagnetic waves are randomly incident from both sides of the composite, it maintains excellent EMI shielding performance. In summary, this type of composite with excellent EMI shielding performance can be used in applications where flexibility, lightweight, and bendable conditions are the primary requirements.