Making a Robust Interfacial Scaffold: Bijel Rheology and its Link to Processability

Abstract

Confocal microscopy and rheology studies of two bijel systems are presented to elucidate relationships between the physicochemical properties of bijels and their ability to be utilized as soft matter templates for materials synthesis. For the first time, the origins of viscoelasticity in these systems are investigated using conventional rheometry and a direct correspondence between the elastic storage modulus, particle loading, and the departure from criticality is observed. Further, the rheological transitions that accompany fluid re‐mixing in bijels are characterized, providing key insights into the synergistic role of interfacial tension and interparticle interactions in mediating their mechanical robustness. Bijels that are predominantly stabilized by interfacial tension are also highly sensitive to gradients in chemical composition and more easily prone to mechanical failure during processing. Despite this increased sensitivity, a modified strategy for processing these more delicate systems is developed and its efficacy is demonstrated by synthesizing a bicontinuous macroporous hydrogel scaffold.

Continuous Fabrication of Hierarchical and Asymmetric Bijel Microparticles, Fibers, and Membranes by Solvent Transfer‐Induced Phase Separation (STRIPS)

“…The asymmetric drop shape evolution strongly suggests that the suspension is viscoelastic, which we attribute to the gelation and interfacial attachment of nanoparticles. [ 29 ] These droplets form complex shaped bijel microparticles of nonuniform lengths as they fl ow through the device. To better regulate drop pinch off, control over the suspension wetting on the inner capillary is critical, and is achieved by coating the capillary with a cationic polyelectrolyte, poly(diallyldimethylammonium chloride).…”

Dynamics and rheology of nonpolar bijels

“…We also found that the particle framework formed at the interface maintains even after the PS/PB phases are re-mixed. Although this so-called ''monogel'' structure has been reported in polar bijels, 18,20 we argue that the formation of a particle framework in nonpolar bijels arises from the nonpolar nature of particle-matrix and inter-particle interactions.…”

Dynamic wetting: status and prospective of single particle based experiments and simulations

“…In froth flotation for example, the adsorption of particles is exploited for mineral extraction [4]. More recently particle assembly at fluid interfaces has been studied as a platform for the design of novel colloid-based materials [5][6][7][8][9][10][11][12][13]. In addition, the interaction between particles and fluid interfaces is important for the field of lab-on-a-chip biosensing, where particles are used for their large surface-to volume ratio, flexible bio-functionalization, stability, and for their actuation and detection properties (see e.g.…”