Molten fatty acid based microemulsions †

International audiencea We show that ternary mixtures of water (polar phase), myristic acid (MA, apolar phase) and cetyltrimethyl-ammonium bromide (CTAB, cationic surfactant) studied above the melting point of myristic acid allow the preparation of microemulsions without adding a salt or a co-surfactant. The combination of SANS, SAXS/ WAXS, DSC, and phase diagram determination allows a complete characterization of the structures and interactions between components in the molten fatty acid based microemulsions. For the different structures characterized (microemulsion, lamellar or hexagonal phases), a similar thermal behaviour is observed for all ternary MA/CTAB/water monophasic samples and for binary MA/CTAB mixtures without water: crystalline myristic acid melts at 52 1C, and a thermal transition at 70 1C is assigned to the breaking of hydrogen bounds inside the mixed myristic acid/CTAB complex (being the surfactant film in the ternary system). Water determines the film curvature, hence the structures observed at high temperature, but does not influence the thermal behaviour of the ternary system. Myristic acid is partitioned in two ''species'' that behave independently: pure myristic acid and myristic acid associated with CTAB to form an equimolar complex that plays the role of the surfactant film. We therefore show that myristic acid plays the role of a solvent (oil) and a co-surfactant allowing the fine tuning of the structure of oil and water mixtures. This solvosurfactant behaviour of long chain fatty acid opens the way for new formulations with a complex structure without the addition of any extra compound

Digressions: On Essaying in the U.K.

These conversations grew out of a curiosity about the possibilities of the hybridity of the essay and from a shared interest in how the essay and essay-publishing are working in the U.K. In this Listening Tour, relative strangers utilize the opportunity of an unexpected conversation to attempt to capture the fleeting, often excessive and heightened movement of essays – considering a wide range of topics, from triptychs and pretention to Barthes and post-partum art. Here essayists, editors and publishers think out loud about form and context and try to handle this slippery, digressive, cunning, non-genre genre

Quenched microemulsions: a new route to proton conductors

International audienceSolid-state proton conductors operating under mild temperature conditions (T < 150 [degree]C) would promote the use of electrochemical devices as fuel cells. Alternatives to the water-sensitive membranes made of perfluorinated sulfonated polymers require the use of protogenic moieties bearing phosphates/phosphonates or imidazole groups. Here, we formulate microemulsions using water, a cationic surfactant (cetyltrimethyl ammonium bromide, CTAB) and a fatty acid (myristic acid, MA). The fatty acid acts both as an oil phase above its melting point (52 [degree]C) and as a protogenic moiety. We demonstrate that the mixed MA-CTA film presents significant proton conductivity. Furthermore, bicontinuous microemulsions are found in the water-CTAB-MA phase diagram above 52 [degree]C, where molten MA plays both the role of the oil phase and the co-surfactant. This indicates that the hydrogen-bond rich MA-CTA film can be formulated in the molten phase. The microemulsion converts into a lamellar phase upon solidification at room temperature. Our results demonstrate the potential of such self-assembled materials for the design of bulk proton conductors, but also highlight the necessity to control the evolution of the nanostructure upon solidification of the oil phase

Tumor cell survival in response to swift-ion irradiation

International audienc

Tumor cell survival in response to swift-ion irradiation

International audienc

Tumor cell survival in response to swift-ion irradiation

International audienc