High-performance multifunctional fGNs@PDA/PVA composites with superior thermal conductivity, electromagnetic interference shielding, and mechanical strength for advanced thermal management applications

Highly integrated and power-dense electronic systems require materials that can simultaneously dissipate heat and mitigate electromagnetic interference, as both thermal hotspots and electromagnetic radiation compromise device stability and lifetime. Thermally conductive polymer composites are attractive for electronic packaging, but their performance is limited by discontinuous phonon-transport networks, filler restacking, and interfacial thermal resistance. Herein, a multiscale interfacial and architectural engineering strategy is developed to construct multifunctional polydopamine-coated exfoliated graphene/poly (vinyl alcohol) (fGNs@PDA/PVA) composite films. Commercial graphene nanosheets were first treated by CTAB-assisted exfoliation to reduce restacking and improve surface accessibility. A PDA interfacial layer was introduced as a noncovalent molecular bridge to improve graphene dispersion and interfacial coupling with PVA, while vacuum-assisted filtration and hot pressing assembled the fillers into a highly oriented layered architecture for in-plane phonon transport. The fGNs@PDA/PVA film achieved an in-plane thermal conductivity of 12.73 W m −1 K −1 at 40 wt%, corresponding to a 38.78-fold enhancement over pristine PVA and 2.8 times that of GNs/PVA. Theoretical calculations show that PDA increases the filler–matrix binding energy from 0.512 to 1.637 eV and strengthens interfacial interactions. The composite also delivered an EMI shielding effectiveness of 32 dB in the X-band and a tensile strength of 43.21 MPa, 74.1% higher than that of pure PVA. LED cooling tests further confirmed faster heat spreading and accelerated cooling of the 40 wt% fGNs@PDA/PVA film compared with pristine PVA. This work demonstrates a practical and scalable approach for designing multifunctional polymer composites capable of addressing the dual challenges of thermal management and EMI shielding in advanced electronic systems.