Sugar-Templated 3D GnP@PDMS/CoNi@C Composites for Absorption Dominant EMI Shielding and Efficient Thermal Management

The rapid growth of electronic devices has created an increasing demand for lightweight polymer composites that can provide effective electromagnetic interference (EMI) shielding while efficiently dissipating heat. In this study, a three-dimensional (3D) dual-network composite based on graphene nanoplatelets (GnP), polydimethylsiloxane (PDMS), and metal-organic framework (MOF)-derived magnetic nanoparticles was developed for absorption-dominant EMI shielding and enhanced thermal conductivity. A porous GnP@PDMS skeleton was first prepared using a sugar-templating method, followed by the vacuum-assisted infiltration of carbonized magnetic nanoparticles derived from Co/Ni MOF. This process produced an interconnected conductive–magnetic network throughout the composite. The synergistic interaction between the conductive GnP network and magnetic phase improved impedance matching, magnetic loss, and interfacial polarization, resulting in a transition from reflection-dominant to absorption-dominant shielding. The optimized composite exhibited excellent EMI shielding performance, a substantially enhanced absorption coefficient, and improved through-plane thermal conductivity. Moreover, it demonstrated efficient heat dissipation, good mechanical strength, thermal stability, and hydrophobicity. These results demonstrate that dual-network engineering of conductive and magnetic phases is an effective strategy for developing multifunctional polymer composites for EMI shielding and thermal management in advanced electronic applications. *This work was supported by the Korea National University of Transportation in 2026.