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Our project is focused on the development of a continuous encapsulation process based on the crossing of an interface by droplets of an active ingredient that have to be encapsulated. The aqueous drops are injected in an organic phase, and as the system rotates each drop is driven outwards until it reaches the interface. Under adequate conditions, it crosses the interface and at a high inertia it drives a volume of organic phase which constitutes the coating

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In this paper we present geometrical measurements made on aqueous polyacrylamide gels withlab-based micro-tomography, one of the most convenient ways of accessing a quantitative measurement of thefascinating shapes that these materials make when hanging under their own weight.

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Ref Arxiv: 1811.06903
DOI: 10.1039/c7sm00596b
WoS: WOS:000411436600003
Ref. & Cit.: NASA ADS
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5 Citations
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Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating- free method at the air-water interface using silylated castor oil cross-linked via a sol-gel reaction. To understand the mechanism of the hybrid film formation, the reaction kinetics was studied in detail by using complementary techniques: rheology, thermogravimetric analysis, and infrared spectroscopy. The mechanical properties of the final films were investigated by nano-indentation, whereas their structure was studied using a combination of wide-angle X-ray scattering, electron diffraction, and atomic force microscopy. We found that solid and transparent films form in 24 hours and, by changing the silica precursor to castor oil ratio, their mechanical properties are tunable in the MPa-range by about a factor of twenty. In addition to that, a possible optimization of the cross-linking reaction with different catalysts was explored and finally, cytotoxicity tests were performed on fibroblasts proving the absence of film toxicity. The results of this work pave the way to a straightforward synthesis of castor-oil films with tunable mechanical properties: hybrid films cross-linked at the air-water interface combine an easy and cheap spreading protocol with the features of their thermal history optimized for possible future micro/nano drug loading, thus representing excellent candidates for the replacement of non-environment friendly petroleum-based materials.

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Des solutions colloïdales sont assez facilement obtenues à partir de nanoparticules de carbone (nanotubes ou dérivés du graphène) dispersées dans l’eau [1]. L’obtention de mésophases nécessite cependant un soin expérimental dans le tri des nanoparticules et dans la qualité des dispersions. La persistance de fortes interactions attractives et d’agrégats dans une solution peuvent en effet déstabiliser lentement ces phases ou au mieux modifier fortement leurs propriétés visco-élastiques. Depuis plusieurs années, nous étudions comment obtenir à partir de ces solutions, des films et couches minces de propriétés variables en contrôlant les conditions de préparation et de dépôts (orientation des particules, texturation).
Dans ce travail, nous décrirons comment créer et stabiliser des textures périodiques de grande échelle dans des phases nématiques d’oxyde de graphène (voir fig.1). Ces textures ont été caractérisées en microscopie optique et électronique et nous discuterons de leur origine et de leur stabilité.
Références:
[1] C. Zakri, et al. Phil. Trans. R. Soc. A., , 2013, 371, 20120499.

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DOI: 10.1039/c7nr02976d
WoS: WOS:000408435400019
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Ionic transport through single-walled carbon nanotubes (SWCNTs) is promising for many applications but remains both experimentally challenging and highly debated. Here we report ionic current measurements through microfluidic devices containing one or several SWCNTs of diameter of 1.2 to 2 nm unexpectedly showing a linear or a voltage-activated I-V dependence. Transition from an activated to a linear behavior, and stochastic fluctuations between different current levels were notably observed. For linear devices, the high conductance confirmed with different chloride salts indicates that the nanotube/water interface exhibits both a high surface charge density and flow slippage, in agreement with previous reports. In addition, the sublinear dependence of the conductance on the salt concentration points toward a charge-regulation mechanism. Theoretical modelling and computer simulations show that the voltage-activated behavior can be accounted for by the presence of local energy barriers along or at the ends of the nanotube. Raman spectroscopy reveals strain fluctuations along the tubes induced by the polymer matrix but displays insufficient doping or variations of doping to account for the apparent surface charge density and energy barriers revealed by ion transport measurements. Finally, experimental evidence points toward environment-sensitive chemical moieties at the nanotube mouths as being responsible for the energy barriers causing the activated transport of ions through SWCNTs within this diameter range.

Ref HAL: hal-01517065_v1
DOI: 10.1111/ijac.12637
WoS: WOS:000397509500020
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The recycling process toward the elimination of varistor wastes into new electro-active silicon composites has been investigated. We studied the dependence of the E-J characteristics on the aggregate content in the polymer matrix. Formulations with 40 vol.% metal oxide varistor aggregates in the 100-200m range exhibit reliable nonlinear behavior with a switching voltage of 280 +/- 30V/mm. The breakdown voltage of the composite decreases as both filler's diameter and filler's volume fraction increases in the 550-220V/mm and 440-280V/mm range, respectively. This paves the way for the valorization of varistors based zinc oxide (ZnO) ceramics.