Anne-Laure Fameau

Gas marbles are particle-stabilized soft dispersed systems consisting of a soap-bubble-like air-in-water-in-air architecture. Herein, we report gas marbles stabilized by polystyrene particles carrying poly(acrylic acid) (PAA) steric stabilizers, which impart alkaline-responsive behavior to the assemblies. Unlike liquid marbles prepared from the same particles, the gas marbles could be fabricated over a broad size range while maintaining an almost perfectly spherical shape. They also exhibited remarkable stability on aqueous surfaces under acidic and neutral conditions, whereas exposure to alkaline solutions induced rapid disruption and release of the encapsulated gas owing to deprotonation of the surface-grafted PAA chains. In addition, the lifetime of the gas marbles was found to be strongly governed by evaporation of the thin water layer surrounding the gas core. Increasing the ambient relative humidity prolonged the lifetime from only a few tens of minutes at a relative humidity below 40% to more than 7 days above 70%. Furthermore, the gas marbles exhibited amphibious motion, allowing repeated transfer between air–water and air–solid interfaces while maintaining their integrity. These findings demonstrate that interfacial particle design and environmental conditions provide effective means of controlling gas-marble stability and responsiveness, establishing a basis for future studies on gas encapsulation, transport, and triggered release.

Intensive global agricultural growth has increased pesticide use, raising concerns about water contamination. Paraquat (PQ), a highly water-soluble, nonselective herbicide used in over 130 countries, poses serious risks to human health because its high solubility and long environmental half-life make it a persistent pollutant. Although conventional analytical methods provide excellent sensitivity, they require expensive instruments and complex sample preparation, limiting their practicality for on-site applications. Here, we present a fast, visual, on-site paraquat detection strategy based on smart liquid foam systems. The method exploits a highly selective host–guest complex between water soluble pillar[5]arene (WS-P[5]A) and PQ. First, WS-P[5]A hosts are loaded with the bio-based surfactant sucrose laurate (SL), that interacts less with WS-P[5]A than PQ. Secondly, PQ is added which replaces SL due to the higher binding constant between WS-P[5]A and PQ. Upon replacement of SL by PQ, surfactant is released which enables foam generation by hand-shaking. Changes in foam height correlate with PQ concentration, providing an intuitive visual readout. We demonstrate a high selective method even in the presence of competing contaminants, and we validate its performance across multiple water types. This supramolecular foam sensor offers a simple, selective, quick and field-ready approach for on-site paraquat detection.

Oil foams are emerging as a promising, versatile system in food, cosmetic and pharmaceutical applications. Existing solutions depend on the addition of particles or surfactant crystallization; however, these approaches often require complex processing steps, introduce solid residues that may affect texture, and rely on kinetically trapped interfacial structures that limit reversibility under ambient conditions. Here, we examine the foamability and stability of food-grade, soybean lecithin in oil with different surface tensions. We found that edible oil foams can be formed at room temperature only in long-chain triglyceride oils. By combining microscopy, X-ray techniques, and interfacial rheology, we show that the stabilization arises from the formation of inverse lipid bilayers at the air-oil surface, leading to increased surface elasticity and dense thin-films that protect the gas bubbles against coalescence and drainage. We also discovered that different self-assembled structures are formed in different oils, which is attributed to the surfactant-oil van der Waals interactions and the oil penetration between the surfactants, at the air-oil surface. These findings uncover a molecular mechanism for non-aqueous foam stabilization under ambient conditions and establish design principles for surfactant-stabilized oil foams, without particle additives or crystallization.

(Text in French) Vegetable oil foams: from stabilization mechanisms to food applications. Oil foams represent a new category of liquid foams, defined as non-aqueous systems containing gas bubbles dispersed within a vegetable oil matrix. They are generating increasing interest in the food, cosmetic, and pharmaceutical sectors due to their ability to stabilize water-free formulations while delivering innovative sensorial properties, as well as their potential to replace solid fats. This article provides an overview of current knowledge on the formation mechanisms of oil foams, whether based on crystalline particles or hydrocarbon surfactants, and on the principles underlying their stabilization. It also highlights the scientific and technological challenges that remain to be addressed, along with future development perspectives.

We report a practical application of using 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) to temper dark chocolate. Building upon prior research where 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) was used to direct CB crystallization into the desired Form V polymorph, we investigated whether DMPE could achieve superior results without the structural defects observed with DMPC-tempered chocolate. Chocolate samples containing 0.1 wt % DMPE were prepared and compared to chocolates tempered with DMPC, as well as commercially tempered and statically cooled controls. Small-angle X-ray scattering (SAXS) revealed that the DMPE addition induced the formation of the Form V polymorph, with no detectable amounts of Form IV polymorph, which is often associated with reduced shelf life and fat bloom in chocolate products. Unlike the DMPC-tempered samples, the DMPE chocolate exhibited no blooming or structural defects such as cracks upon prolonged storage. Small-angle neutron scattering (SANS) experiments showed no evidence of micelle formation by DMPE, suggesting a mechanism distinct from that of DMPC. Fourier transform infrared (FTIR) spectroscopy and attenuated total reflectance imaging indicated no significant chemical interactions between DMPE and the main triacylglycerol (TAG) in CB, 1-palmitoyl-2-oleoyl-3-stearoyl-sn-glycerol (POS). We propose that DMPE acts as a unique tempering particle, which facilitates the formation of the stable Form V polymorph and the correct chocolate microstructure through physical interactions with the crystallizing TAGs on its surface. Moreover, DMPE addition also prevents localized material contraction and bloom development due to the absence of induced lattice strain. Crystallization kinetics of the cocoa butter component of chocolate shows an acceleration of crystallization induced by DMPE at 28 °C, relative to both the native refined cocoa butter and the refined cocoa butter containing DMPC. Polarized light micrographs supported this observation. Isolated seed crystals from cocoa butter showed an enrichment in POS and POP in DMPE chocolate, and a characteristic Form V polymorphism for these seeds, in contrast to both native refined cocoa butter and refined cocoa butter with DMPC, where Form IV was identified at the onset of crystallization. The addition of DMPE to chocolate simplifies the tempering process, potentially reducing production costs and energy consumption, and enhancing the quality and stability of the final product, benefiting both artisanal chocolatiers and large-scale manufacturers.