Ionic liquids (ILs) are a new class of organic solvents that are stable over a large range of temperatures and have negligible vapor pressures.[1] Owing to their molecular structure, associating a cation and an anion, their physicochemical properties can be easily modulated by changing one of the ions. Ionic liquids are now widely used in organic synthesis and chemical separations due to their high solvation ability and their tuneable nature. [2,3] Almost unexplored, surfactant organization in ILs could open new research directions towards micellar catalysis into IL media, solvation enhancement for apolar entities and lyotropic properties. Indeed, surfactant organization occurs in some nonaqueous solvents [4,5] and is largely used in aqueous systems for drug vectorization, catalysis, gelification and other applications.[5] Recently, microemulsions have been obtained in IL-oil mixtures [6] and only premicellar aggregation has been detected in pure ILs. [7,8] However, no clear demonstration of the existence of a micellar phase in ILs has been reported yet.Here, we describe the behavior of a series of pure alkyl poly-(oxyethyleneglycol) ethers in 1-butyl-3-methyl-imidazolium (bmim) ILs with various counter ions [BF 4 À , PF 6 À and Tf 2 N À , that is, bis(trifluoromethylsulfonyl)amide; Figure 1]. The choice of nonionic surfactants, denoted C n E m (n = 12-16; m = 4-8), was justified to avoid the exchange of counter ions with the solvent. For high concentrations of surfactant (ca. 1 mol L À1 ), the mixtures C n E m /bmimBF 4 were generally solid at room temperature with a cloud point at high temperature (see Supporting Information). Herein, all experiments were performed at 25 8C with concentrations lower than 1 mol L À1, at which the mixtures were all limpid and homogeneous.Surface tension measurements were performed to probe the aggregation behavior of the surfactants in bmimBF 4 . For all the selected surfactants, the surface tension of the C n E m /bmimBF 4 solutions decreased when the surfactant concentration increased (Figure 2). This indicated their adsorption at the air/solution interface. The Szyszowski-Langmuir adsorption equation [9] fitted well this decrease, leading to an estimation of the area per molecule of the surfactant at the air/bmimBF 4 interface, that occurred to be comparable or lower than the ones found at the air/water interface (Table 1). Those differences between bmimBF 4 and water may be related to a change in the organization and/or solvation state of the adsorbed surfactants. In bmimBF 4 like in water, the molecular area of the surfactant decreased with increasing alkyl chain length or decreasing number of oxyethylene groups.This initial decrease of the surface tension is followed by an abrupt change in the slope of the surface tension versus C (Figure 3; semi-log plot). After this breaking point, the surface tension of the solutions remains more or less constant. Such a behavior suggested the formation of micelles within the ILs, where the break point corresponds to a critical micelle...

Raspberrylike hybrid organic-inorganic materials consisting of spherical silica beads supporting smaller polystyrene particles were prepared through a heterophase polymerization process. In a first step, micrometer-sized silica particles were synthesized according to procedures inspired from the literature. In a second step, a poly(ethylene glycol) macromonomer was adsorbed on the surface of the silica beads. Finally, polymerization of styrene was achieved in water with a nonionic surfactant as an emulsifying agent and sodium persulfate as an initiator. Scanning and transmission electron microscopies show that the presence of the macromonomer on the surface of the silica particles is a determining parameter in order to get the raspberrylike morphology.

The synthesis of composite particles with original morphologies resulting from the combination of an inorganic silica seed and polymer nodules is reported. To promote association between both components, the silica seeds are previously functionalized with an appropriate coupling agent carrying polymerizable groups. Following classical recipes, emulsion polymerization of styrene is achieved in the presence of these surface-modified particles and polystyrene is formed exclusively at the surface of the inorganic precursors. The density of the coupling agent, however, as well as the silica seed diameter have a strong influence on the particle morphology. In the case when this density is equal to 0.1 molecule nm-2 (that is around 0.17 × 10-6 mol m-2) and the seed size is close to 170 nm, an interesting evolution of the morphology with the reaction time, from daisy-like toward multipod-like, is observed. Thus, the possibility to elaborate original building blocks with a defined shape and size is demonstrated.

The effect of Keggin heteropolyoxotungstates (XW12O40 n - with X = H2, P, Si, B or Co) on Langmuir films has been studied for monolayers of DODA (dimethyldioctadecylammonium) and DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine). Marked modifications of the compression isotherms have been observed when the Keggin anions were dissolved in the subphase:  this demonstrates that the polyanions interact with the monolayer. Langmuir−Blodgett (LB) films have been readily obtained from these systems (even with DPPC) for a particular range in polyanion concentration. X-ray diffraction and infrared dichroism experiments have shown a well-defined lamellar structure for these built-up films as well as the presence within the LB films of polyoxometalates organized in monolayers. Control of the Keggin polyanion amount in the multilayers is made possible by mixing DODA with a negatively charged lipid, which modifies the global electrical charge of the Langmuir film. Such an organic−inorganic system leads to new ultrathin materials having various properties related to the selected polyanions.

Mixing double-hydrophilic block copolymers containing a poly(acrylic acid) block with gadolinium ions in water leads to the spontaneous formation of polymeric nanoparticles. With an average diameter near 20 nm, the nanoparticles are exceptionally stable, even after dilution and over a large range of pH and ionic strength. High magnetic relaxivities were measured in vitro for these biocompatible colloids, and in vivo magnetic resonance imaging on rats demonstrates the potential utility of such polymeric assemblies.

Colloidal particles with a controlled morphology combining both organic and inorganic parts were synthesized through a seeded emulsion polymerization process. Silica seed particles from 50 to 150 nm were first surface-modified by adsorption of an oxyethylene-based macromonomer or covalent grafting of a trialkoxysilane derivative. Then, emulsion polymerization of styrene was carried out in the presence of these particles, the formation of polystyrene nodules being highly favored at the silica surface in such conditions. While varying different experimental parameters, we have demonstrated that the ratio between the number of silica seeds and the number of growing nodules is a key parameter in controlling the morphology of the final hybrid nanoparticles. For instance, in the particular case when this ratio was close to 1, dumbbell-like or snowman-like particles were obtained. Further selective surface modification of their silica moiety was also tested successfully, indicating a potential application of these hybrid particles as original building blocks toward supraparticulate assemblies.

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Janus silica nanoparticles, regioselectively functionalized by two different chemical groups, were synthesized through a multistep procedure based on the use of a polystyrene nodule as a protecting mask.