Research progress on interfacial regulation and structural design of polypyrrole-based electromagnetic wave-absorbing composites

With the rapid development of intelligent electronic devices and radar detection technologies, complex electromagnetic interference and electromagnetic pollution have become increasingly serious. The development of lightweight, broadband and highly efficient electromagnetic wave-absorbing materials is therefore of great significance. Polypyrrole (PPy), a typical intrinsically conducting polymer, has attracted considerable attention in the field of conductive polymer-based microwave absorbing composites owing to its low density, tunable electrical conductivity, facile synthesis and tailorable microstructure. In this review, the electromagnetic wave attenuation mechanisms of PPy-based composites are discussed, with emphasis on the effects of conductive loss, dipole polarization, interfacial polarization, magnetic loss and impedance matching on microwave absorption performance. From the perspectives of interfacial regulation and structural design, recent advances in PPy structural modulation and PPy-based composites incorporating polymers, dielectric fillers, magnetic fillers and multicomponent heterogeneous systems are systematically summarized. Furthermore, the regulation effects of doping modification, microstructure construction, three-dimensional conductive networks, multilevel interface design and magnetic–dielectric synergy on reflection loss and effective absorption bandwidth are discussed. Finally, the current challenges of PPy-based microwave absorbing composites, including low-frequency broadband absorption, multi-performance coordination, service stability and scalable preparation, are outlined. This review is expected to provide useful guidance for the structural design and engineering application of high-performance conductive polymer-based electromagnetic wave absorbing materials.