Insights into Formation of Bicontinuous Emulsion Gels via in-situ (Ultra-)Small Angle X-ray Scattering

TL;DR

This study uses in-situ ultra-small-angle X-ray scattering with microfluidics to reveal the step-by-step formation process of bicontinuous emulsion gels, providing insights into their complex self-assembly mechanisms.

Contribution

It introduces a novel in-situ X-ray scattering approach with high temporal resolution to study bijel formation, advancing understanding of their kinetic self-assembly processes.

Findings

Bijels form via three sequential steps involving fluid mechanics, nanoparticle self-assembly, and phase separation.

The microfluidic setup enables millisecond resolution monitoring of bijel formation.

Structural evolution insights can improve control over bijel synthesis.

Abstract

Nanostructured materials formed via kinetically controlled self-assembly processes gather more interest nowadays. Bicontinuous emulsion gels stabilized by colloidal particles, called bijels, are attractive materials in soft-matter as they combine bulk properties of two immiscible liquids into an interwoven network structure. The limited understanding of the complex formation phenomena of bijels restricts the control over the synthesis, and so its applicability. In this work, in-situ (ultra-) small-angle X-ray scattering is applied to gain insight into the phase separation and self-assembly kinetics of bijels formed via solvent transfer induced phase separation. An X-ray compatible microfluidic setup allows accessing the process kinetics with a millisecond resolution. The formation of such bijels is shown to occur via three consecutive steps related to fluid mechanics, nanoparticle self-assembly and liquid-liquid phase separation. This time-resolved monitor technique offers valuable insights into the structural evolution of kinetically controlled materials and enhances our understanding of the formation of bicontinuous emulsion gels.