Putting interfaces at work

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Full recycling of all the materials, waste waters, and gaseous emissions is an irreversible trend. New processing technologies are required to succeed. The existing processing techniques have reached their limit or simply the processes required do not exist yet. New, high-performance materials will be at the core of the transformation, allowing for extra light structures to be produced, making use of much less materials than what is currently used to provide similar and even superior properties. The proposed program aims at using interfaces (Liquid-Liquid and Gas-liquid) in combination with their affinity with particles having specific surface properties to develop high-selectivity recycling technologies or build high-performance materials with extreme porosity that will minimize the quantify of resources required. The applicant is an expert in the processing of solid-stabilized emulsions (AKA SSEs or Pickering emulsions) and foams. SSE are produced when fine particles (micron- to nano-sized) attach at an interface. The surface chemistry of the particles, combined to the water and the oil chemistry, is crucial for the final result to be a SSE. When conventionally preparing SSEs, it is possible to select all the chemical conditions of each constituent (water, oil and particles) so that an emulsion is produced. So far, SSEs have been produced to be used as is in the cosmetic, pharmaceutical, chemical, and oil refining industries. Two main types of emulsions can be prepared i.e. low and high concentrations where the frontier between the two sits at the maximum packing fraction of identical spheres, around 65% of dispersed phase. Below this value, we name the emulsions SSEs while above, we use HIPE-SSEs for High Internal Phase Emulsions SSEs. The same can be said of foams were gas a liquid are used instead of two liquids. The two main ideas that triggered this program is first that low dispersed content SSEs could be used to harvest particles of interest in separation processes and second that HIPE SSEs could provide templates to build highly porous materials. In both cases, the approach is to investigate the processing required for the potential applications and eventually determine the real potential for such applications at large scale. When the oil content is kept below 40% in volume, SSEs offer the potential to selectively separate ground/crushed materials (raw ore, recycled plastics or biomaterials, glass, .) by controlling the chemistry of the oil and the water phases to make them attractive to the particles targeted. At high oil volume content (HIPE-SSE), the drops are in contact with their neighbours and the interface between the drops offers a continuous structure of particles. Subsequent processing of these emulsions may transform the particles structure into a solid material, after removal of the oil and the water phases with the resulting solid being highly porous.