Fabrication of Bijels via Solvent Transfer-Induced Phase Separation using Liquid-in-Liquid Printing

Abstract

Bicontinuous interfacially jammed emulsion gels or bijels are a new class of soft materials containing both surfactants and particles. They are, however, distinguished from conventional surfactant-stabilized and particle-stabilized systems. Due to the partitioning of percolating sheets of particles in a bicontinuous morphology, the interpenetrating phases are stabilized by kinetically arresting the phase separation process. This leads to the generation of rheological features in bijels with a range of viscoelastic properties based on types, size, anisotropy, and volume fractions of particles. Research on bijels has been around for only about 15 years, and the need for substantial research is recognized in the fabrication of bijels. Herein, the focus is on fabricating on fabricating bijels using solvent transfer-induced phase separation (STRIPS) and from polar oils, cationic/anionic surfactants, and various nanoparticles to investigate their microstructure–properties relation. Using the newly emerged liquid-in-liquid 3D printing approach, the fabrication of these bijels via STRIPS into arbitrary complex designs which are not reported before is shown. The rheological properties of the printed bijels and the baths used for printing are characterized. This work paves the way for the production of bijels using a broader range of materials and hence their application in various fields.