Giorgio Nasillo

Ce:YAG Nanoparticles Embedded in a PMMA Matrix: Preparation and Characterization

A Ce:YAG-poly(methyl methacrylate) composite was prepared using in situ polymerization by embedding the Ce:YAG nanopowder in a blend of methyl methacrylate (MMA) and 2-methacrylic acid (MAA) monomers and activating the photopolymerization using a radical initiator. The obtained nanocomposite was yellow and transparent. Its characterization was performed using transmission electron microscopy, small angle X-ray scattering, (13)C cross-polarization magic-angle spinning nuclear magnetic resonance, and photoluminescence spectroscopy. Results showed that Ce:YAG nanoparticles are well dispersed in the polymeric matrix whose structure is organized in a lamellar shape. The luminescence properties of the nanocomposite do not show quenching or a significant spectral shift, indicating that the nanocomposite can be useful for advanced applications such as white LED construction.

Oxidized graphene in ionic liquids for assembling chemically modified electrodes: a structural and electrochemical characterization study.

Dispersions of graphene oxide (GO) nanoribbons in ionic liquids, ILs (either 1-butyl-3-methylimidazolium chloride (BMIM-Cl-) or 1-butylpyridinium chloride (-Bupy-Cl-)) have been used to assemble modified screen printed electrodes (SPEs). The graphene oxide/ionic liquid dispersions have been morphologically and structurally characterized by the use of several techniques: X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared (FT-IR) spectroscopy, high-resolution-transmission electron microscopy (HR-TEM). The assembled modified SPEs have then been challenged with various compounds and compared to several electro-active targets. In all cases high peak currents were detected, as well as significant potential shifts, especially in the detection of catecholamines and NADH, compared with the bare SPE and the conventional electrodes, such as glassy carbon (GC) and highly oriented pyrolitic graphite (HOPG). This opens the way to the assembly of new types of sensors and biosensors. The enhanced performances observed are attributed to electrocatalytic effects related to the high electrode surface area, to oxygen-assisted electron transfer, as well as to the disordering effect of the ILs, this latter related to the favorable π-π interactions with the ILs and the GO plane.

Thermal Properties, Raman Spectroscopy and Tem Images of Neutron-Bombarded Graphite

Neutron-irradiated graphite to a total dose of 3.6 × 1016 n cm−2 was studied by DSC, Raman spectroscopy and transmission electron microscopy (TEM). The Wigner energy of neutron-irradiated graphite was 9.5 J/g as measured by DSC; it was released with an exothermal peak at 220°C. The Raman spectroscopy has confirmed the expected effect caused by neutron irradiation of the graphite substrate. The TEM imaging has shown that neutron-irradiated graphite can be effectively exfoliated by sonication in comparison to pristine graphite, which under similar conditions does not exfoliate at all. The interstitial Frenkel defects in neutron-irradiated graphite are intercalated between the graphene layers of the graphite and favor the exfoliation under adequate conditions.

Effect of Elongational Flow and Polarity of Organomodified Clay on Morphology and Mechanical Properties of a PLA Based Nanobiocomposite

Abstract In biodegradable polymer world nanobiocomposites represent a new group of materials filled with inert nanoparticles that shows very interesting properties and the biodegradability of the matrix. In this work we have studied the effect of the polarity of the organomodified montmorillonite and of the elongational flow on the morphology and the rheological and mechanical properties of a new nanobiocomposite with a matrix of biodegradable PLA based blend. The elastic modulus enhances in presence of the nanofiller and this increase is larger and larger with the increment of the orientation. The tensile strength does not show any significant change at the same level of orientation. Moreover, a brittle-to-ductile transition is observed in the anisotropic sample and this effect is again more evident for the nanocomposite. The raise of the interlayer distance is higher for the more polar montmorillonite, even if the two nanocomposites show about the same final interlayer distance and morphology. Some exfoliation is also observed as a result of the application of the elongational flow.

Structural characterization of zirconia nanoparticles prepared by microwave-hydrothermal synthesis

Nanocrystalline zirconia powders have been prepared by microwave-hydrothermal synthesis starting from aqueous solution of ZrOCl2·8H2O. Results of investigations on the aqueous suspension stability of the washed zirconia nanopowders by dynamic light scattering showed that the suspension, constituted by superaggregates of nanoparticles (131 ± 10 nm), was stable up to 15 days. Nanopowders were investigated by means of transmission electron microscopy and small angle x-ray scattering measurements which proved that the zirconia nanopowder is constituted by small primary nanoparticles of ca. 8 nm that agglomerate forming bigger aggregates of 50 ± 1 nm.

Organic-inorganic nanocomposites prepared by reactive suspension method: investigation on filler/matrix interactions and their effect on the nanoparticles dispersion

Epoxy resin/TiO2 nanocomposites prepared by both reactivesuspension method, based on in situ synthesis, and conventional mechanical mixing are analysed by solid-state nuclear magnetic resonance and transmission electron microscopy in order to have a deeper insight into the nature of interactions at the polymer/particle interface and their effect on the nanoparticles dispersion. Specifically, solid-state nuclear magnetic resonance experiments showed that the nanoparticles, synthesized by reactive suspension method, can efficiently link the matrix by hydrogen bonds forming a hybrid organic-inorganic 3D network. Such evidences strongly supports our previously reported theory, in which the nanoparticles in situ synthesized by reactive suspension method act not only as rigid filler, but also as actual cross-linking points, dramatically improving the mechanical properties of the polymeric matrix. Moreover, as revealed by transmission electron microscopy investigations, the formation of such hydrogen bonds significantly affect also the nanoparticles distribution, thanks to a stabilizing effect on the nanoparticles’ surface that prevents their aggregation and improves their dispersion.