Design of Nanohybrid Systems from a Partially Fluorinated Organogelator and Syndiotactic Polystyrene Thermoreversible Gel.

Nanohybrid systems are prepared from organogels of a partially fluorinated molecule and from thermoreversible gels of syndiotactic polystyrene. The thermodynamic behavior, morphology, and structure are investigated by using differential scanning calorimetry, atomic force microscopy, small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS). The outcomes of these investigations suggest that the fibrils of the organogel coil around the sPS fibrils, probably through a heterogeneous nucleation process. These systems therefore differ from previously investigated sPS/OPV systems (oligo vinylene phenylene) where OPV fibrils pervade the sPS network.

On the behaviour of nanoparticles in oil-in-water emulsions with different surfactants.

The distribution of narrowly dispersed gold nanoparticles in hexane-in-water emulsions was studied for different surfactants. Good surfactants such as SDS and Triton X-100 block the oil-water interfaces and confine particles in the droplet. Other surfactants (Tween 85 and Span 20) form synergistic mixtures with the nanoparticles at the interfaces that lower the surface tension more than any component. Supraparticles with fully defined particle distribution form in the droplets only for surfactants that block the interface. Other surfactants promote the formation of fcc agglomerates. Nanoparticles in emulsions behave markedly different from microparticles-their structure formation is governed by free energy minimization, while microparticles are dominated by kinetics.

Nanoparticle clusters with Lennard-Jones geometries.

Noble gas and metal atoms form minimum-energy clusters. Here, we present analogous agglomerates of gold nanoparticles formed in oil-in-water emulsions. We exclude interfacial templating and nucleation-and-growth as formation mechanisms of these supraparticles. Similar to atomic clusters, the supraparticles form when a mobile precursor state can reconfigure until the nanoparticles' interactions with each other and with the liquid-liquid interface are maximized. This formation mechanism is in striking contrast to that previously reported for microparticle clusters.