Multifunctional polymer composites and nanomaterials for high-performance microwave shielding: a review

Abstract The rapid growth of wireless communication technologies has increased the need for effective microwave shielding to ensure device reliability and reduce electromagnetic pollution. Polymer composites have become viable alternatives to traditional metal-based electromagnetic interference (EMI) shielding due to their lightweight, corrosion-resistant, and tunable electrical, magnetic, and mechanical properties. However, conventional highly conductive shields, which primarily reflect incident waves, can lead to secondary electromagnetic interference. The challenge is to develop absorption-dominant, “green” EMI shields, which requires careful material selection and innovative structural design. This review provides an in-depth analysis of recent developments in EMI shielding materials, focusing on carbon-based nanomaterials, metals and alloys, MXenes, and polymer-based composites. It explores the underlying shielding mechanisms, including dielectric loss, magnetic loss, and internal multi-reflections, along with structural features and processing strategies. Emphasis is placed on techniques to maximize absorption and minimize reflection, such as gradient conductivity, porous structures, and multilayered interfaces. Finally, the review discusses future challenges and highlights the need for scalable fabrication of impedance-matched, absorption-dominant structures to meet the demands of future electronic and aerospace applications.