Graphene-Oxide-Based Interfacial GO–Polymer Assemblies Stabilize Pickering Emulsions for 3D-Printed Multifunctional Cryogels

Graphene oxide (GO)-based interfacial assemblies offer exceptional mechanical and functional properties, yet scalable fabrication of freestanding films and their integration into complex architectures remain challenging. Here, we demonstrate the fabrication of large-area, freestanding polystyrene (PS)/GO interfacial nanoparticle–ligand thin films through interfacial coassembly of carboxyl-functionalized GO and amine-terminated PS at the water/toluene interface. The resulting ultrathin films (8–11 nm) span diameters up to 0.15 mm and exhibit a tunable Young’s modulus of 0.21–0.72 GPa by varying pH, PS molecular weight, and component concentrations. Guided by these interfacial insights, GO together with octadecylamine (ODA) was further used to stabilize high-internal-phase Pickering emulsions as direct-ink-writing (DIW)-compatible inks. Rheological characterization revealed shear-thinning behavior, finite yield stress, and rapid structural recovery after high shear, which collectively support continuous extrusion and shape retention during printing. Freeze-drying preserves the emulsion-templated porosity to yield ultralight cryogels, and subsequent thermal reduction converts GO to conductive reduced GO, giving an electrical conductivity of 297 S·cm –1 and a thermal conductivity of 0.092 W·m –1 ·K –1, thereby demonstrating proof-of-concept multifunctionality. This work establishes a scalable and integrated platform that bridges interfacial self-assembly, emulsion templating, and 3D printing to design multifunctional GO-based materials for potential applications in soft electronics and thermal management.