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This research aims at improving barrier properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, by incorporating boron nitride particles (BNPs) via melt compounding. To meet this objective, PHBV nanocomposite samples containing different BNPs were prepared and the effects of BN loading and silane surface modifier on the barrier properties of PHBV nanocomposites were investigated. For all the nanocomposite samples, the permeability is decreased in comparison to the neat PHBV due to both the presence of BN particles and a higher crystallinity. The results demonstrate that barrier properties of the composites were found to increase more for the silanized flake type BN (OSFBN) compared to silanized hexagonal disk type BN (OSBN). The best barrier properties are obtained for the nanocomposite sample containing 2 wt% OSFBN, for which a reduction of oxygen permeability up to 36% was observed in comparison to the neat PHBV. Silane-treated BN nanoparticles yielded nanocomposites characterized by good barrier performance and fine BN dispersion, as shown by SEM investigations. The phenomenological gas permeation models were employed to evaluate the effect of BN particles on oxygen transmission properties. The best approach was found for the relative permeation by using Cussler and Lape models. POLYM. COMPOS., 40:78-90, 2019. (c) 2017 Society of Plastics Engineers

International audience; We report on the investigation of optical and structural properties of Al2O3/ZnO nanolaminates. The nanolaminates were deposited on Si and glass substrates by Atomic layer deposition method. Structural properties of nanolaminates were studied by SEM, GIXRD, and AFM. Optical characterization was performed by transmittance and photoluminescence spectroscopy. Complex analysis of monolayer properties was done by ellipsometry. Optical constants for Al2O3 and ZnO monolayer were calculated.

Atomic layer deposition (ALD) is a thin film technology that in the past two decades rapidly developed from a niche technology to an established method. It proved to be a key technology for the surface modification and the fabrication of complex nanostructured materials. In this Progress Report, after a short introduction to ALD and its chemistry, the versatility of the technique for the fabrication of novel functional materials will be discussed. Selected examples, focused on its use for the engineering of nanostructures targeting applications in energy conversion and storage, and on environmental issues, will be discussed. Finally, the challenges that ALD is now facing in terms of materials fabrication and processing will be also tackled.

Surface-enhanced Raman spectroscopy is based on the absorption of light by nanometer-sized metal particles, resulting in large enhancement of the Raman signal. By replacing the metal particles by a metallic nanotip, the enhancement can be localized. The resulting tip-enhanced Raman spectroscopy is capable of measuring Raman spectra with high spatial resolution, effectively overcoming the diffraction limit. A successful tip-enhanced Raman spectroscopy experiment depends heavily on the ability to fabricate tips of a definite metal with the appropriate shape and size, which is still a challenging process. We have prepared silver nanowires with a diameter of 200–300 nm by templated electrochemical deposition and attached them onto atomic force microscope cantilevers by focused electron beam induced deposition. We found that they produce a reproducible enhancement of the Raman signal intensity. Other metals and smaller nanostructures might also be produced, suggesting an interesting development potential for these novel nanoprobes. Copyright © 2011 John Wiley & Sons, Ltd.

International audience

We present here highly sensitive measurements of nanowire mechanical resonances by analyzing Field Emission Microscopy (FEM) images from the nanowires while they are excited by sinusoidally time-varying voltages. Numerical analysis of the image blurring during frequency sweeps through resonances are shown to allow detection with = 100 x higher sensitivity as compared to our previous measurements where they were detected by the changes in the total field emission (FE) current. Furthermore since FEM approximately measures the end angle of the nanowire, this detection is more sensitive to higher resonance modes which in general have much smaller amplitudes. Observation of the mechanical response of SiC nanowires in FEM shows that they almost always present non linear mechanical behavior with large hysteresis and abrupt jump effects in their frequency response that are related to the large applied electric field. We approach the linear regime by reducing the excitation voltage and by using the sensitive image detection method.

International audience; The nanoparticle colorimetric-based methods have been extensively used for rapid detection, however there are few limitations which can be kept under control or avoided by understanding the crucial parameters involved in these reactions. This review addresses the main parameters that influence colorimetric-based methods and provides a rational classification of the current approaches, by focusing particularly on gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs). The AgNP and AuNP-based colorimetric assays can be very efficient and sensitive especially for biomolecule identification and for metal ion detection in environmental screening. Specifically, this review highlights the detection of metal ions through their coordination with nanoparticle stabilizing ligands. The review also addresses various approaches based on label-free aptasensors to better understand their role as smart colorimetric sensing devices.

Atomic layer deposition (ALD) is a thin film technology that in the past two decades rapidly developed from a niche technology to an established method. It proved to be a key technology for the surface modification and the fabrication of complex nanostructured materials. In this Progress Report, after a short introduction to ALD and its chemistry, the versatility of the technique for the fabrication of novel functional materials will be discussed. Selected examples, focused on its use for the engineering of nanostructures targeting applications in energy conversion and storage, and on environmental issues, will be discussed. Finally, the challenges that ALD is now facing in terms of materials fabrication and processing will be also tackled.