From interfacially complexed structured liquids to electromagnetic shielding aerogels

This thesis explores the innovative use of interfacial complexation to develop a versatile approach for manufacturing functional aerogels. The approach leverages structured liquids as engineerable templates for aerogel production, enabling precise control over the composition and features of aerogels from the nano-scale material chemistry and micro-scale nanoparticle-surfactant assemblies to the macro-scale porous architecture. This high degree of customization facilitated the creation of diverse 3D porous macroscopic constructs, including filamentous, free-standing, and 3D-printed aerogels. Such versatility addresses key challenges in porous construct manufacturing, including enhancing mechanical properties, fine-tuning multi-scale porosities, engineering macroscopic morphologies, inducing stimuli responsiveness, and tailoring compositions for advanced functional applications. The study begins with the synthesis and characterization of essential nanomaterials, including graphene oxide (GO), magnetic graphene oxide (mGO), and cellulose nanofibers (CNF), which serve as the primary building blocks for aerogel construction. This is followed by the design and optimization of the interfacial complexation technique, which involves nanoparticle jamming at the interface of immiscible liquids (oil/water) and stabilizing the non-equilibrium shape of the resulting structured liquids as templates for aerogel production. This approach led to the creation of ultra-lightweight, flexible, and multi-scale porous filamentous aerogels with customizable compositions, where GO played a critical role in maintaining the structured liquid integrity. Controlling aerogel features during the liquid structuring stage enabled the production of a wide range of functional aerogels, with a specific focus on electromagnetic (EM) shielding applications. The concept of "aerogel electromagnetic traps" was then introduced, yielding filamentous aerogels capable of capturing and dissipating incident EM waves as well as those reflected from highly conductive metallic substrates, effectively addressing key challenges in EM shielding science. Finally, an interfacially driven oil-in-water (O/W) emulsion templating method was developed, enabling scalable manufacturing of free-standing or 3D-printed aerogels with tunable mechanical properties and EMI shielding performance. This technique utilized post-jamming ionic crosslinking to modify the rheological properties of the emulsion ink, facilitating 3D printing via direct ink writing (DIW) and enabling the creation of complex macroscopic geometries. This work pushes the boundaries of functional aerogels, advancing their design and application potential for cutting-edge technological challenges.