Design strategies for wave-absorbing polymer-based electromagnetic shielding materials: a review
Traditional electromagnetic interference (EMI) shielding materials rely on high electrical conductivity to enhance reflection and absorption losses, achieving high shielding effectiveness but causing impedance mismatch, elevated surface reflectivity, and irreversible secondary electromagnetic pollution. This review critically evaluates performance criteria and material-structure factors governing low-reflectivity EMI shielding. It synthesizes recent advances in polymer-based composites incorporating conductive fillers such as graphene, carbon nanotubes, silver nanowires, and MXene, and examines tuning mechanisms including gradient and segregated conductive networks, multilayer architectures, and foaming. Key experimental benchmarks from the literature are analyzed: multilayer MXene/cellulose films, PBAT composite foams, and ferroelectric PVDF-TrFE-MXene composites demonstrate absorption-dominated shielding with reflectivity reductions of 30–50% relative to homogeneous conductive counterparts. The review identifies persistent challenges in balancing conductivity, impedance matching, and mechanical robustness, and outlines future directions for sustainable, low-reflectivity shielding materials in 5G communication, wearable electronics, and aerospace applications.