Periodic Reporting for period 4 - 3D-FABRIC (3D Flow Analysis in Bijels Reconfigured for Interfacial Catalysis)
Reporting period: 2023-12-01 to 2024-11-30
Solvents are essential in many chemical processes involving immiscible reagents and are critical to the production of pharmaceuticals, polymers, fuels, and more. However, they account for up to 50% of the energy used in industrial reactions. In 2013 alone, 6.5 million tons of alcohol-based solvents were used globally. Solvent separation and recycling significantly raise the cost and complexity of chemical manufacturing.
Solvent-free biphasic reactions, such as those used in the Shell higher olefin and Ruhrchemie/Rhône-Poulenc hydroformylation processes, offer advantages in energy efficiency and process integration. Yet, these reactions are typically batch-based, limiting scalability. Continuous flow systems for such reactions are highly desirable to improve efficiency and output.
The 3D-FABRIC project addresses this by developing catalytic nanomaterials that enable continuous reaction and separation of immiscible reagents. Central to this approach is the bijel—a sponge-like structure composed of interwoven oil and water channels stabilized by a rigid nanoparticle network. These nanostructured materials offer high surface area, tunable flow pathways, and catalytic functionality, making them ideal for continuous flow chemistry.
3D-FABRIC focuses on three core objectives: (a) synthesizing bijels with tailored structure–function properties, (b) reinforcing bijels for mechanical stability, and (c) enabling continuous synthesis of specialty chemicals. This work aims to establish a scalable platform for sustainable chemical production, including biofuels and pharmaceuticals.
Solvent-free biphasic reactions, such as those used in the Shell higher olefin and Ruhrchemie/Rhône-Poulenc hydroformylation processes, offer advantages in energy efficiency and process integration. Yet, these reactions are typically batch-based, limiting scalability. Continuous flow systems for such reactions are highly desirable to improve efficiency and output.
The 3D-FABRIC project addresses this by developing catalytic nanomaterials that enable continuous reaction and separation of immiscible reagents. Central to this approach is the bijel—a sponge-like structure composed of interwoven oil and water channels stabilized by a rigid nanoparticle network. These nanostructured materials offer high surface area, tunable flow pathways, and catalytic functionality, making them ideal for continuous flow chemistry.
3D-FABRIC focuses on three core objectives: (a) synthesizing bijels with tailored structure–function properties, (b) reinforcing bijels for mechanical stability, and (c) enabling continuous synthesis of specialty chemicals. This work aims to establish a scalable platform for sustainable chemical production, including biofuels and pharmaceuticals.
Objective (a): Control over Bijel Structure
We have made significant progress in understanding and controlling bijel (bicontinuous interfacially jammed emulsion gel) structure. Our efforts advanced the synthesis of bijels with continuous channel networks at submicrometer scales. We elucidated the underlying mechanisms of bijel formation using silica and alumina nanoparticles, demonstrating how self-assembly occurs during the phase separation of oil and water. The role of surfactants in facilitating bijel formation was systematically investigated, alongside the development of surfactant-free bijels stabilized solely by nanoparticles. These findings are broadly applicable to various bijel systems.
To support this, we developed innovative sample preparation techniques, including rapid screening methods and controlled printing processes for device fabrication. We also studied the fluid dynamics involved in bijel formation to optimize fabrication parameters.
Detailed insights into bijel formation dynamics were obtained using small-angle X-ray scattering (SAXS) at the European Synchrotron Radiation Facility (ESRF). This allowed us to identify key mechanisms of phase separation and nanoparticle assembly, and to demonstrate how these kinetics can be tuned through component concentration and additive introduction.
Objective (b): Reinforcement and Surface Functionalization of Bijels
We developed two reinforcement strategies for bijels. The first creates composite structures by integrating bijels with varied mechanical properties, enhancing overall strength and flexibility. The second approach chemically binds nanoparticles using tetraalkoxysilanes, acting as a "mortar" within the structure. This method has been generalized across different silane chemistries, and the reinforced structures were characterized via SAXS at ESRF.
We also focused on tuning the surface charge of bijels, a critical requirement for fluid transport (Objective c). Surface charge control was achieved through: (1) fabrication using highly charged nanoparticles, and (2) post-synthesis ionization of nanoparticle surfaces in reinforced bijels.
Objective (c): Liquid Transport and Functional Operation of Bijels
We discovered a method to induce liquid flow through bijels using an applied electrical voltage, which enables electrokinetic transport through the microscopic channels. We quantified flow rates as a function of voltage and bijel composition. Confocal laser scanning microscopy (CLSM) combined with fluorescence techniques was employed to visualize chemical transport through the bijel. In parallel, computational simulations were developed to predict transport rates and were validated against experimental data.
Additionally, we identified key factors affecting the long-term stability of the bijel’s fluid network. Specifically, we addressed the challenge of preventing unwanted rearrangement of the oil and water phases, which could disrupt continuous fluid transport. This stability enabled us to achieve, for the first time, continuous liquid-liquid extraction within a bijel. We studied solute transport from a flowing oil phase into a water phase moved electrokinetically through the bijel. Extraction rates were experimentally evaluated and simulated under varying flow conditions.
Exploitation and Dissemination
The results of this project have laid the foundation for advanced applications in membrane technology, soft robotics, and microfluidic devices. We are currently disseminating our findings through high-impact journal publications, international conferences, and workshops. Potential exploitation paths are being explored in collaboration with industrial partners, particularly in the areas of separations, sensing, and responsive materials.
We have made significant progress in understanding and controlling bijel (bicontinuous interfacially jammed emulsion gel) structure. Our efforts advanced the synthesis of bijels with continuous channel networks at submicrometer scales. We elucidated the underlying mechanisms of bijel formation using silica and alumina nanoparticles, demonstrating how self-assembly occurs during the phase separation of oil and water. The role of surfactants in facilitating bijel formation was systematically investigated, alongside the development of surfactant-free bijels stabilized solely by nanoparticles. These findings are broadly applicable to various bijel systems.
To support this, we developed innovative sample preparation techniques, including rapid screening methods and controlled printing processes for device fabrication. We also studied the fluid dynamics involved in bijel formation to optimize fabrication parameters.
Detailed insights into bijel formation dynamics were obtained using small-angle X-ray scattering (SAXS) at the European Synchrotron Radiation Facility (ESRF). This allowed us to identify key mechanisms of phase separation and nanoparticle assembly, and to demonstrate how these kinetics can be tuned through component concentration and additive introduction.
Objective (b): Reinforcement and Surface Functionalization of Bijels
We developed two reinforcement strategies for bijels. The first creates composite structures by integrating bijels with varied mechanical properties, enhancing overall strength and flexibility. The second approach chemically binds nanoparticles using tetraalkoxysilanes, acting as a "mortar" within the structure. This method has been generalized across different silane chemistries, and the reinforced structures were characterized via SAXS at ESRF.
We also focused on tuning the surface charge of bijels, a critical requirement for fluid transport (Objective c). Surface charge control was achieved through: (1) fabrication using highly charged nanoparticles, and (2) post-synthesis ionization of nanoparticle surfaces in reinforced bijels.
Objective (c): Liquid Transport and Functional Operation of Bijels
We discovered a method to induce liquid flow through bijels using an applied electrical voltage, which enables electrokinetic transport through the microscopic channels. We quantified flow rates as a function of voltage and bijel composition. Confocal laser scanning microscopy (CLSM) combined with fluorescence techniques was employed to visualize chemical transport through the bijel. In parallel, computational simulations were developed to predict transport rates and were validated against experimental data.
Additionally, we identified key factors affecting the long-term stability of the bijel’s fluid network. Specifically, we addressed the challenge of preventing unwanted rearrangement of the oil and water phases, which could disrupt continuous fluid transport. This stability enabled us to achieve, for the first time, continuous liquid-liquid extraction within a bijel. We studied solute transport from a flowing oil phase into a water phase moved electrokinetically through the bijel. Extraction rates were experimentally evaluated and simulated under varying flow conditions.
Exploitation and Dissemination
The results of this project have laid the foundation for advanced applications in membrane technology, soft robotics, and microfluidic devices. We are currently disseminating our findings through high-impact journal publications, international conferences, and workshops. Potential exploitation paths are being explored in collaboration with industrial partners, particularly in the areas of separations, sensing, and responsive materials.
Our advancements in bijel synthesis have yielded materials with the highest internal surface areas reported to date. The use of low-cost, commercially available raw materials and a scalable continuous production process make bijels a promising candidate for large-scale applications. The reinforcement techniques developed in the 3D-FABRIC project are broadly applicable, extending beyond bijels to enable the fabrication of composite materials from hydrogels, emulsions, and polymers—creating multifunctional structures with synergistic properties.
For the first time, we have demonstrated convective liquid flow through bijels—an achievement long anticipated since the concept was first introduced in the seminal 2005 publication but never previously realized experimentally. In addition, we established the continuous operation of liquid–liquid extraction within bijels, showcasing their potential for separation processes relevant to the chemical industry.
These breakthroughs pave the way for new applications in continuous molecular separations and catalysis. Future work will focus on developing bijel synthesis methods that incorporate catalytic building blocks, and on optimizing reinforcement strategies using polymers to create highly stable, mechanically robust bijels. These next-generation bijels will feature tunable permeability for use in continuous flow chemical processes.
For the first time, we have demonstrated convective liquid flow through bijels—an achievement long anticipated since the concept was first introduced in the seminal 2005 publication but never previously realized experimentally. In addition, we established the continuous operation of liquid–liquid extraction within bijels, showcasing their potential for separation processes relevant to the chemical industry.
These breakthroughs pave the way for new applications in continuous molecular separations and catalysis. Future work will focus on developing bijel synthesis methods that incorporate catalytic building blocks, and on optimizing reinforcement strategies using polymers to create highly stable, mechanically robust bijels. These next-generation bijels will feature tunable permeability for use in continuous flow chemical processes.