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Iron oxide nanocrystals, synthesized by surfactant-assisted thermal decomposition of Fe(CO)(5), were selectively incorporated into the microseparated PS block phase of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer to design novel nanostructured inorganic/organic materials with magnetic properties. The colloidal synthesis led to oleic acid- and oleylamine- capped magnetic gamma-Fe2O3 maghemite nanocrystals, which resulted well-dispersible in the block copolymer up to 60 wt % due to the affinity between PS block and organic surfactants. Atomic force and scanning electron microscopy confirmed that nanocomposites with nanocrystal loading lower than 40 wt % maintained cylindrical morphology, even without additional treatment applied to enhance their nanostructuration. Nanocrystals appeared well-dispersed in the nanocomposites at low contents, while nanocrystal clusters, with size depending on their loading, were observed at higher contents. At the highest nanocrystal content, the nanostructured area size decreased and nanocrystals covered the entire surface. Magnetic force microscopy measurements confirmed the magnetic behavior of gamma-Fe2O3 nanocrystals confined in PS block of PS-b-PMMA block copolymer after applying UV treatment to the samples. The results demonstrated that the incorporation of as-synthesized colloidal iron oxide nanocrystals (up to 40%) in self-assembled PS-b-PMMA block copolymer offers a simple and direct approach to successfully design and fabricate novel nanostructured magnetic composites.

Au nanoparticles (NPs) self-assembled by means of a simple solvent evaporation strategy in a two-dimensional (2D) superlattice with a highly controlled geometry and extending over micrometers squared when drop cast onto a suitably functionalized silicon substrate. The assembly procedure was defined by carefully monitoring experimental parameters, namely, dispersing solvent, deposition temperature, Au NP concentration, and chemistry of supporting substrate. The investigated parameters were demonstrated to play a significant role on the delicate energetic balance of the mutual NPs as well as NP-substrate interactions, ultimately directing the NP assembly. Remarkably, substrate surface chemistry revealed to be decisive to control the extent of the organization. Scanning electron microscopy demonstrated that the 2D superlattice extends uniformly over hundreds of square micrometers. Grazing-incidence small-angle X-ray scattering investigation validated the Au NP organization in crystalline domains and confirmed the role played by the surface chemistry of the substrate onto the 2D lattice assembly. Finally, preliminary spectroscopic ellipsometry investigation allowed extraction of optical constants of NP assemblies. The localized surface plasmon resonance modes of the NP assemblies were studied through a combined analysis of reflection, transmission, and ellipsometric data that demonstrated that the plasmonic properties of the Au NP assemblies strongly depend on the substrate, which was found to influence NP ordering and near-field interactions between NPs. © 2014 American Chemical Society.

One of the most recent developments at the forefront of nanotechnology is the attempt to exploit quantum phenomena in nanometer scale materials, exploring novel applications of quantum effects. An ...

Signatures of long-lived quantum coherence in light-harvesting complexes invoked a hypothesis that the protein-scaffold vibrations assist energy transfer by bridging energy gaps. To address this hy...