<scp>HGM</scp> ‐Assisted Dispersion of Graphene Nanoplatelets for Enhancing <scp>EMI</scp> Shielding Effectiveness of the Syntactic <scp>PVDF</scp> Foam Composites

ABSTRACT Lightweight poly (vinylidene fluoride) (PVDF) syntactic foams reinforced with hollow glass microspheres (HGMs) and graphene nanoplatelets (GNPs) were developed for high‐performance electromagnetic interference (EMI) shielding. Fabricated via a simple solution‐casting route, the PVDF syntactic foam composites exhibited uniform GNP dispersion facilitated by HGM‐induced interfacial anchoring. Structural analyses confirmed the continuous GNP networks, while FE‐SEM revealed close hollow spheres, interconnected morphologies favorable for multiple internal scattering of electromagnetic waves. The composites displayed a percolation threshold at 8–14 wt% GNP, with conductivity rising from 0.18 to 1.12 S/cm. Dielectric studies highlighted strong interfacial polarization and Maxwell–Wagner–Sillars relaxation, promoting absorption‐dominated shielding. Thermal stability and char yield were also enhanced with increasing filler content. In the X‐band (8.2–12.4 GHz), EMI shielding effectiveness increased from 20.39 to 26.93 dB, with absorption loss (i.e., 16–20 dB) dominating over reflection loss (i.e., &lt; 7 dB). A maximum specific shielding effectiveness of 1788 dB·cm 2 /g was achieved at 8 wt% GNP owing to the ultralow density (0.095 g/cm 3 ). Unlike conventional PVDF/GNP systems, this dual‐functional design leverages HGMs for simultaneous weight reduction and multiple reflections, offering a scalable strategy for ultralight, absorption‐driven EMI shields.