(87a) Tailoring of Bijel Fibers and Membranes By Mass Transfer-Induced Liquid-Liquid Phase Separation of Ternary Mixtures

Bicontinuous interfacially jammed emulsions (Bijels) are novel soft materials with potential applications in areas ranging from healthcare, cosmetics, and food to energy and diverse chemical technologies. However, their fabrication is currently limited to only two pairs of immiscible liquids with narrow temperature windows for their formation.  In such systems, typical bicontinuous domain sizes are in the range of tens of micrometers, and fabrication is inefficient due to its batch-wise nature and expensive starting materials. We explore the formation of bijels by mass transfer induced ternary liquid-liquid phase separation. The use of commercially available silica nanoparticles and ionic surfactants allows us to continuously form bijel fibers and membranes with controllable morphologies and domain sizes down to only a few hundreds of nanometers. We study the dependence of fiber morphology on different control parameters such as particle and surfactant concentration. Confocal and electron microscopy reveal hierarchical fiber architectures remarkably similar to polymer membranes formed via non-solvent induced phase inversion. However, unlike their polymeric counterparts, bijel fibers remain entirely liquid throughout their volume. This unique feature combined with the hierarchical morphology opens avenues to new applications such as bijel microfluidics or interfacial catalysis.