Polymerization interface design in wrinkled ferrite@PPy core–shell composites to boost electromagnetic wave absorption

Abstract

The design of polymer-magnetic heterointerfaces plays a critical role in tuning the dielectric properties and provides a promising strategy for developing broadband electromagnetic (EM) wave absorption materials. Herein, novel polymer-coated ferrite composites for high-performance EM wave absorption were studied in detail. Firstly, ferrites (ZnNiFe₂O₄, ZNFO) with distinct morphologies (ZNFO-M microspheres, ZNFO-W wrinkled microspheres, and ZNFO-F flakes) were synthesized via spray-drying and subsequent pyrolysis. After an in situ polymerization reaction, PPy-coated ferrite (ZNFO@PPy) composites were formed, resulting in a unique core–shell magnetic-dielectric absorption system. Interestingly, the surface morphology of the ferrite cores significantly influenced the EM properties of the final ZNFO@PPy composites, tuning the impedance and loss characteristics. The wrinkled ZNFO@PPy-W composite achieved an outstanding absorption ability with a minimum reflection loss (RL_min) of 56.8 dB at only 1.5 mm thickness, which was attributed to the optimized impedance matching and synergistic magnetic-dielectric loss mechanisms. The core–shell wrinkled magnetic@polymer structure enhanced the interfacial polarization, while the conductive PPy layer improved the dielectric loss. This morphology-dependent EM regulation provides a new route to fabricate outstanding EM wave dissipation systems.