C. Riccucci

Flame retardant properties of plasma pre-treated/diamond-like carbon (DLC) coated cotton fabrics

Textiles with superior anti-flammability properties combined with minimal environmental impact are extremely necessary to reduce fire-related issues. In this regard, diamond-like carbon (DLC) coatings on cotton fabrics may represent promising candidates as potential flame-retardant (FR) materials. Herein, superhydrophobic and fire-resistant cotton fabrics were fabricated through a two-step plasma strategy by alternately exposing substrates to H2 and O2 plasma pre-treatments and subsequent DLC deposition. Fourier transform-infrared spectroscopy analysis has revealed that different plasma pre-treatments can impose surface modifications on the chemical structure of cotton, especially in carboxylic and hydroxyl groups, leading to a radical alteration of surface roughness and of the crystalline cellulosic external structure. These changes deeply influenced the growth of DLC thin films and the surface properties of cotton fabric because of the combination of a hierarchical structure and surface chemistry as verified using field emission gun-scanning electron microscopy and water contact angle measurements. The effects of both specific gases used in the pre-treatment step and duration of pre-treatment were analysed and compared using thermogravimetric analyses. The H2-pre-treated DLC cottons exhibited good potential as an FR material, showing improved thermal stability in respect to untreated cotton, as evidenced by increased ignition times. Moreover, vertical burning tests have demonstrated that DLC-cotton systems exhibit enhanced flammability resistance.

β-Cyclodextrin-grafted on multiwalled carbon nanotubes as versatile nanoplatform for entrapment of guanine-based drugs

The design of β-cyclodextrin/multiwalled carbon nanotubes hybrid (β-CD-MWCNT) as nanoplatform for the entrapment and delivery of guanine based drugs is described here. The functionalized carbon nanomaterials have been characterized by XPS spectroscopy, electron microscopy (FEG-SEM and TEM), AFM, TGA, and FT-IR to achieve insights on structure, morphology and chemical composition. The drug binding abilities of nanocarrier towards the guanine (G) and Acyclovir (Acy) were proved by UV-vis and DSC experiments. Host-guest equilibrium association constants and drug loading have been evaluated for G/β-CD-MWCNT and Acy/β-CD-MWCNT complexes. The release studies showed a sustained delivery of Acy without initial burst effect confirming a strong interaction of drug with the nanoplatform sites. The preliminary antiviral data indicated that the Acyclovir loaded into the β-CD-MWCNT platform interferes with HSV-1 replication and the antireplicative effect was higher than the free drug.

Double-Wall Nanotubes and Graphene Nanoplatelets for Hybrid Conductive Adhesives with Enhanced Thermal and Electrical Conductivity

Improving the electrical and thermal properties of conductive adhesives is essential for the fabrication of compact microelectronic and optoelectronic power devices. Here we report on the addition of a commercially available conductive resin with double-wall carbon nanotubes and graphene nanoplatelets that yields simultaneously improved thermal and electrical conductivity. Using isopropanol as a common solvent for the debundling of nanotubes, exfoliation of graphene, and dispersion of the carbon nanostructures in the epoxy resin, we obtain a nanostructured conducting adhesive with thermal conductivity of ∼12 W/mK and resistivity down to 30 μΩ cm at very small loadings (1% w/w for nanotubes and 0.01% w/w for graphene). The low filler content allows one to keep almost unchanged the glass-transition temperature, the viscosity, and the curing parameters. Die shear measurements show that the nanostructured resins fulfill the MIL-STD-883 requirements when bonding gold-metalized SMD components, even after repeated thermal cycling. The same procedure has been validated on a high-conductivity resin characterized by a higher viscosity, on which we have doubled the thermal conductivity and quadrupled the electrical conductivity. Graphene yields better performances with respect to nanotubes in terms of conductivity and filler quantity needed to improve the resin. We have finally applied the nanostructured resins to bond GaN-based high-electron-mobility transistors in power-amplifier circuits. We observe a decrease of the GaN peak and average temperatures of, respectively, ∼30 °C and ∼10 °C, with respect to the pristine resin. The obtained results are important for the fabrication of advanced packaging materials in power electronic and microwave applications and fit the technological roadmap for CNTs, graphene, and hybrid systems.

Inhibition of bronze corrosion in 3%NaCl media by novel non-toxic 3-phenyl-1,2,4-triazole thione formulation

Abstract Bronzes are largely used in various domains such as battery connectors, archaeological artefacts and urban statues, suffering from corrosion process leading to the formation of corrosion products. A protection treatment could be used to insulate them from this environment. In this way we contribute to the protection of bronze in the environment by use of organic corrosion inhibitors. In this work a novel organic compound (3-phenyl-1·2·4-triazole-5-thione) was tested as a corrosion inhibitor on a pure reference bronze alloy (CNR alloy). The electrochemical behaviour was investigated in 3%NaCl solution, in the presence and absence of the inhibitor formulation using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS). The obtained results confirm that the compound is a good corrosion inhibitor which acts reduce both cathodic and anodic reactions rates. The inhibiting efficiency was found to be about 97% at 2·5 mM of inhibitor concentration. SEM coupled with EDX and XPS analysis confirms the good protective effect due to the establishment of an inhibitor film on the bronze sample.

Novel route to high-yield synthesis of sp2-hybridized boron nitride nanoplates on stainless steel

The synthesis of randomly distributed sp2-BN nanoplates embedded in a steel matrix was achieved by using boron doped AISI 316 stainless steel as substrates and a dissociated anhydrous NH3 atmosphere at 1070 °C as the nitrogen source. The chemical and morphological nature of the BN nanoplates has been studied by means of the combined use of XPS, FESEM-EDS, FTIR, XRD and SIMS techniques. The BN nanoplates are generally 100–400 nm wide and in many cases are characterised by a triangular or quasitriangular shape with some truncated and broken nanoplates that form a film whose thickness varies from 45 to 60 nm as a function of the boron content. This synthesis has the potential for coating stainless steel vacuum components and vessel walls with a stable film inert to gas adsorption to be used for the production of the next-generation of high performance stainless steel components for vacuum technology such as particle accelerators, thin film deposition and surface analysis equipment and further, as precursors for the fabrication of c-BN nanoplates.

Spectroscopic and Morphological Studies of Metal-Organic and Metal-Free Dyes onto Titania Films for Dye-Sensitized Solar Cells

We have investigated the spectroscopic behavior of three different sensitizers adsorbed onto titania thin films in order to gain information both on the electron transfer process from dye to titania and on the anchorage of the chromophore onto the semiconductor. We have examined by UV-Vis and fluorescence spectroscopy the widely used ruthenium complex cis-di(thiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II) (N719), the more recently developed organic molecular 3-(5-(4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acid (D5), and a push-pull zinc phthalocyanine sensitizer (ZnPc). Three type of titania films with different morphology, characterized by SEM and FT-IR measurement, were considered: a mesoporous transparent film deposited by spin-coating (TiMS), a semiopaque film deposited by doctor-blade from mesoporous titania (TiMS_DB) and a semiopaque film deposited by doctor-blade form commercial P25 titania (P25_DB). The use of TiMS is responsible for the adsorption of a higher amount of dye since the mesoporous structure allows increasing the interfacial area between dye and titania. Moreover, the fluorescence emission peak is weaker when the sensitizers are adsorbed onto TiMS. These findings suggest that mesostructured films could be considered the most promising substrates to realize photoanodes with a fast electron transfer process.