(38b) Structure Control of Arrested Bicontinuous Channels Via a New Type of Colloidal Gel

With high specific surface area and interconnected channels, bicontinuous structures are widely used in many research fields, such as energy storage, catalysis, membrane science and biomedical applications. Being able to manipulate the structures of the bicontinuous channels is of vital importance to further improve the materials with better performance. Here, we are presenting a systematic study of ways to control the bicontinuous channel structures via the self-assembly of a colloidal gel, namely solvent segregation driven gel (SeedGel). Previously, we demonstrated SeedGel as a scalable method to arrest bicontinuous channels with great thermo-reversibility and high reproducibility. In this work, detailed discussions will be given for controlling the formed bicontinous structure by controlling particle concentration, solvent ratio, temperature, and quenching rate. Small-angle neutron scattering (SANS), combined with ultra-small angle neutron scattering (USANS), provides quantitative characterization of structures over a wide range of length scales, from nanometer to tens of micrometers. A phase diagram of a model SeedGel using highly charged silica nanoparticles dispersions in a binary solvent of water and 2,6-lutidine is successfully identified. By adjusting the sample composition, bicontinuous structures with well-defined repeating distances are produced. Dynamically tunable channel width is achieved by simply changing the temperature ramping rate, which is potentially suitable for a large variety of applications, even with different requirements of the channel size. In the high-temperature range, domain coarsening is observed beyond a critical temperature while the local particle packing remains unchanged. This greatly distinguishes SeedGel from bicontinuous interfacially jammed emulsion gel (Bijel), another well-studied system to arrest bicontinuous structures. This work provides valuable insights into designing controlled bicontinuous structures via SeedGel, which is a great approach to customize materials for different applications.