Ionic‐Liquid‐Assisted Synthesis of Graphene Nanoplatelets/Magnetite Hybrid and Dispersion in Ethylene–Vinyl Acetate ( <scp>EVA</scp> ) Copolymer for High‐Performance Electromagnetic‐Absorbers

ABSTRACT This study investigates the use of ionic liquids (ILs) to prepare graphene nanoplatelets (GNP)/magnetite (Fe 3 O 4 ) hybrid fillers for incorporation into an ethylene‐vinyl acetate (EVA) polymer matrix, with the goal of developing high‐performance electromagnetic (EM) wave‐absorbing composites. The work focuses on optimizing the synergistic interactions between dielectric (GNP) and magnetic (Fe 3 O 4 ) components to enhance absorption across the X‐band (8–12 GHz) and Ku‐band (12–18 GHz) frequency ranges. Hybrid fillers composed of Fe 3 O 4 /GNP, including IL‐modified variants, were synthesized via a co‐precipitation route and subsequently incorporated into EVA through melt processing. Comprehensive characterization, including thermogravimetric analysis (TGA), dynamic light scattering (DLS), UV–Vis spectroscopy, x‐ray diffraction (XRD), and electrical impedance spectroscopy, revealed that the Fe 3 O 4 @GNP hybrid and IL hybrids exhibited optimal thermal stability, uniform dispersion, and reduced particle size (~68 nm). Electromagnetic performance measurements showed that the EVA/Fe 3 O 4 @GNP composite achieved a reflection loss (RL) of −40 dB in the Ku‐band, while the inclusion of ILs in the hybrids further broadened the effective absorption bandwidth (EAB) to values exceeding 4 GHz. Overall, these findings highlight the strong potential of the developed composites for electromagnetic interference (EMI) shielding, and other advanced wireless communication technologies.