3D-Printed\nInterfacially Jammed Emulsion Aerogels

3D printing ultralightweight porous\nstructures using direct ink\nwriting (DIW) while maintaining their mechanical robustness is highly\nchallenging. This difficulty is amplified when low ink concentrations\nare used to create complex geometries. Herein, this shortfall was\naddressed by interfacially jammed emulsion gels. The gel emerged from\nthe electrostatic interaction among synergized nanomaterials (graphene\noxide (GO) and cellulose nanocrystals (CNCs)) in the aqueous phase\nand a ligand in the oil phase. This interaction led to the jamming\nof the nanoparticles and the creation of stable emulsion gels. The\nformed interfacial assemblies were further treated by post-jamming\nionic cross-linking with NaHCO<sub>3</sub>, which dictated the emulsion\ngels’ rheological characteristics, enhancing the ink’s\nviscoelastic properties for high-resolution 3D printing. The customizable\nemulsion system allows control over porosity from the macro- to the\nmicro-scale and generates complex geometries with desired compositions.\nBy manipulating post-annealing processes and varying concentrations,\nit is possible to achieve aerogels that feature a remarkably low density\n(∼2.63 mg/cm<sup>3</sup>) and adjustable mechanical robustness\n(elastic modulus of 0.45 MPa). Additionally, this method allows for\nproducing aerogels with flexible or stiff characteristics as required,\nalongside the capability to tailor specific electromagnetic shielding\neffectiveness (ranging from 6791 to 19615 dB cm<sup>2</sup>/g), showcasing\nthe technique’s versatility and engineerability.