Synthesis and properties of nanohybrid materials with SiO2 and epoxy resin.

SiO2-epoxy nanohybrid materials were synthesized by hybridization of surface-modified colloidal silica nanoparticle (CS) and epoxy resin. The CS was surface-modified with either methyltrimethoxysilane (MTMS) or phenyltrimethoxysilane (PTMS) followed by the solvent exchange with dimethylacetamide (DMAc) to have a homogenous dispersion in epoxy resin. Various amounts of surface-modified CS were mixed with epoxy resin. The chemical structures of surface-modified CS were investigated with FT-IR spectroscopy. The particle sizes of CS and surface-modified CS were measured with DLS. The morphology of hybrid materials analyzed using FE-SEM and AFM showed homogeneous dispersion in epoxy resin. The optical and thermal properties of the hybrid materials determined by refractive index meter and DSC were lower in RI and higher in Tg than neat epoxy resin, respectively.

Effect of SiO2-acryl nanohybrid coating layers on transparent conducting oxide-poly(ethylene terephthalate) superstrate.

SiO2-acryl nanohybrid coating layers were produced by hybridizing acrylic resin and surface-modified colloidal silica (CS) nanoparticles. First, CS nanoparticles were modified with methyltrimethoxysilane (MTMS) and vinyltrimethoxysilane (VTMS) by a sol-gel process. The surface-modified CS nanoparticles were then solvent-exchanged to be homogeneous in acrylic resin. The Hybrid materials were mixed in variation with the amount of surface-modified CS nanoparticles, coated with poly(ethylene terephthalate) (PET), then finally cured by UV light to obtain a hybrid coating layer. Field emission scanning electron microscopy (FE-SEM), particle size analysis (using a Zetasizer), and atomic force microscopy (AFM) were performed to determine the morphology of the hybrid thin-films. Thermogravimetric analysis (TGA) was used to investigate the thermal properties. Fourier-transform infrared (FTIR), ultraviolet-visible (UVNis) spectroscopies, and pencil hardness were used to obtain the details of chemical structures, optical properties, and hardness, respectively. The hybrid thin films had shown to be enhanced properties compared to their urethane acrylate prepolymer (UAP) coating film.

High dielectric loss in graphite-coated Ti nanocapsules.

Graphite-coated Ti nanocapsules, with Ti nanoparticles as core and onion-like graphite layers as shell, have been prepared by a modified arc-discharge method in ethanol atmosphere, and characterized by means of X-ray diffraction, transmission electron microscopy and Raman spectroscopy. The dielectric properties of the graphite-coated Ti nanocapsules have been investigated in the 2-18 GHz range. An equivalent circuit model was used to interpret the non-linear dielectric resonance behavior of the graphite-coated Ti nanocapsules. The high dielectric loss is mainly attributed to conductance loss and dipole-relaxation loss in the graphite-coated Ti nanocapsules. The graphite-coated Ti nanocapsules exhibit promising properties for application as a new type of shield or absorbent of electromagnetic waves.

Controlled growth of vertically aligned ZnO nanowires with different crystal orientation of the ZnO seed layer.

A novel synthesis and growth method achieving vertically aligned zinc oxide (ZnO) nanowires on a silicon dioxide (SiO(2)) coated silicon (Si) substrate is demonstrated. The growth direction of the ZnO nanowires is determined by the crystal structure of the ZnO seed layer, which is formed by the oxidation of a DC-sputtered Zn film. The [002] crystal direction of the seed layer is dominant under optimized thickness of the Zn film and thermal treatment. Vertically aligned ZnO nanowires on SiO(2) coated Si substrate are realized from the appropriately thick oxidized Zn seed layer by a vapor-solid growth mechanism by catalyst-free thermal chemical vapor deposition (CVD). These experimental results raise the possibility of using the nanowires as functional blocks for high-density integration systems and/or photonic applications.

Fluorescence scanning near-field optical microscopy of polyfluorene composites.

Fluorescence scanning near-field optical microscopy (SNOM) is used to investigate binary polyfluorene-based composites of varying composition. The samples investigated contain blends of the polymer poly(9,9'-dioctylfluorene-cobenzothiadiazole), F8BT, with similar polyfluorenes of wider band gap. Images acquired from a film containing 50% by weight F8BT exhibit a high degree of correlation between the topography and fluorescence, with an F8BT-rich phase which protrudes from the surface of the film forming isolated regions with sizes from hundreds of nanometres to several micrometres. A film containing 10% by weight F8BT also has micrometre-size F8BT-rich regions, but also present are small and locally varying proportions of F8BT in the other polyfluorene component phase, indicating a hierarchy of phases within this sample. The fluorescence and topographic images of a third sample studied, containing 90% by weight F8BT, display no correlation, demonstrating that it is not always appropriate to use topographic information to determine the phase structure within polymer blends. The fluorescence SNOM images acquired from these samples are able to assist our understanding of the photovoltaic efficiency of devices fabricated from these films, which are governed by the extent of the interfacial area between these two constituent polymers.

Enzymatic Synthesis of 6-O-α-D-Galactopyranosyl-1-deoxynojirimycin Using α-Galactosidase from Green Coffee Beans.

A transgalactosylation reaction from p-nitrophenyl-α-D-galactopyranoside to 1-deoxynojirimycin was done using α-galactosidase [EC 3.2.1.22] from green coffee beans. The enzyme formed 6-O-α-D-galactopyranosyl-1-deoxynojirimycin as the major product.