Structural Control Over Bicontinuous Emulsions from Solvent-Transfer Induced Phase Separation Through Nanoparticle Loading.

Bicontinuous materials comprise an interpenetrating network of two continuous phases, demonstrating great potential for overcoming diffusion limitations in applications such as catalysis and energy storage. Bicontinuous interfacially jammed emulsion gels (bijels) formed via solvent-transfer induced phase separation (STrIPS) show particular promise because their constituent nanoparticles enable submicron liquid domains. However, the rational design of diffusion pathways in STrIPS bijels remains challenging due to the unknown scaling between the nanoparticle loading and the domain size. Here, this relationship is investigated by varying the nanoparticle content of STrIPS bijels with a more applied geometry than the typical fibres, namely a supported film. Quantitative analysis with confocal microscopy reveals a decrease in the average domain size with the nanoparticle loading, further forming the basis for both an empirical equation that can predict the bijel film structure and an extended theoretical model to interpret observed morphological trends in terms of limited nanoparticle efficiency. By gaining control over the domain size through the nanoparticle loading, these findings advance the use of supported bijel films as functional materials.