Nanostructured, Fluid‐Bicontinuous Gels for Continuous‐Flow Liquid–Liquid Extraction

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202109547. Fluid-bicontinuous gels are unique materials that allow two distinct fluids to interact through a percolating, rigid scaffold. Current restrictions for their use are the large fluid-channel sizes (>5 µm), limiting the fluid-fluid interaction surface-area, and the inability to flow liquids through the channels. In this work a scalable synthesis route of nanoparticle stabilized fluid-bicontinuous gels with channels sizes below 500 nm and specific surface areas of 2 m 2 cm −3 is introduced. Moreover, it is demonstrated that liquids can be pumped through the fluid-bicontinuous gels via electroosmosis. The fast liquid flow in the fluid-bicontinuous gel facilitates their use for molecular separations in continuous-flow liquid-liquid extraction. Together with the high surface areas, liquid flow through fluid-bicontinuous gels enhances their potential as highly permeable porous materials with possible uses as microreaction media, fuel-cell components, and separation membranes.

Bicontinuous interfacially jammed emulsion gels with nearly uniform sub-micrometer domains via regulated co-solvent removal

“…4,15,16 In comparison to thermal quench-based methods, chemical quenching allows access to much higher interfacial tensions as phase separation proceeds. 17 However, the flow generated by co-solvent removal has a significant impact on the resulting bijels' structures. In solvent transfer-induced phase separation (STRIPS), the partitioning of co-solvent to the outer liquid phase induces a strong flow that drives the formation of anisotropic domains aligned in the direction of the co-solvent flux.…”

“…The ability to form bijels with uniform, sub-micrometer domains would enable their utilization in reactive separation, fluid-fluid extraction, flow batteries, fabrication of anti-cracking composite matrix 19 as well as optics and photonics. For liquid phase reaction and extraction, the large surface area facilitates reaction and mass transfer between two phases 17,20,21 whereas the uniform channels provide homogeneous flow/solute distributions [22][23][24] essential, for example, to flow battery function. For photonics, recent simulation results have proposed that spinodal structures exhibit hyperuniformity 25 making bijel-templated materials potentially useful for designing photonic band gaps.…”

Synthesis and Polyelectrolyte Functionalization of Hollow Fiber Membranes Formed by Solvent Transfer Induced Phase Separation

“…It shall be noted that these equilibrium compositions may not be fully representative for the nonequilibrium process during STrIPS. Nevertheless, our recent work showed that equilibrium compositions can model the nonequilibrium interfacial tension evolution during STrIPS . Therefore, we prepare equilibrium mixtures with compositions in the middle of the tie-lines (ensuring equal volumes of BDA- and water-rich phases) given by points 1, 2, 3, and 4 in Figure b.…”

“…Nevertheless, our recent work showed that equilibrium compositions can model the nonequilibrium interfacial tension evolution during STrIPS. 22 Therefore, we prepare equilibrium mixtures with compositions in the middle of the tie-lines (ensuring equal volumes of BDA-and water-rich phases) given by points 1, 2, 3, and 4 in Figure 6b. The mixtures contain the same Ludox TMA and CTA + concentrations as the compositions used to make the fibers.…”

“…Nanocomposite membranes can be synthesized via NIPS by the direct addition of nanoparticles to the NIPS precursor solution, or via postprocessing of the NIPS membrane. However, the uniform distribution and amount of nanoparticles in the NIPS membranes are limited. , Solvent transfer induced phase separation (STrIPS) is a novel approach to generate nanocomposite membranes with high loadings of nanoparticles within the membrane (up to 50 wt %). − STrIPS nanocomposite membranes are formed by liquid–liquid phase separation and polymerization of precursor dispersions containing tens of weight percentages of well-dispersed nanoparticles. − The tensile strengths (100 kPa–15 MPa) and elastic moduli (100 kPa–1 GPa) of STrIPS membranes can be controlled via postprocessing. , Moreover, compared to NIPS, STrIPS results in membranes made of cross-linked polyacrylates, facilitating their direct use in organic solvent filtration. , Similarly, the cross-linked STrIPS membranes can potentially withstand aggressive cleaning treatments involving acidic, alkaline, chlorine, organic, or oxidizing solutions. STrIPS fiber membranes also evolve hollow interiors by phase separation, simplifying the fiber spinning equipment for the synthesis of hollow fiber membranes.…”