A Template-Free Strategy for Lightweight and Compressible rGO/PVDF-HFP Sponge for Absorption-Dominated...

The growing demand for lightweight materials with efficient electromagnetic (EM) wave absorption capabilities has become critical for next-generation aerospace and electronic applications. In this study, for the first time, three-dimensional (3D) reduced graphene oxide/poly(vinylidene fluoride-co-hexafluoropropylene) (rGO/PVDF-HFP) composite sponges were fabricated using a facile and scalable template-free phase inversion strategy, exhibiting an ultralow density (∼0.065 g/cm3) and high porosity (∼96.37%). The composite sponge exhibited excellent flexibility and mechanical robustness, achieving a compressive strength of ~72 kPa and a Young's modulus of 309 kPa at 50% strain. Furthermore, a total shielding effectiveness of 22.20 dB was achieved at a low rGO loading of 6.75 wt %, where absorption (21.27 dB) dominated over reflection. Moreover, the composite sponge demonstrated effective microwave absorption, reaching an effective absorption bandwidth of ~4.2 GHz at a thickness of 5 mm and a minimum reflection loss of -26.08 dB. The interconnected 3D porous framework promoted efficient charge transport, interfacial polarization, and multiple internal reflections, leading to enhanced attenuation of incident EM waves. This work provides a scalable strategy for designing lightweight, high-performance graphene/polymer-based sponges for advanced absorption-dominated EMI shielding applications.