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.