Densely Packed Linear Assembles of Carbon Nanotube Bundles in Polysiloxane-Based Nanocomposite Films

Linear assemblies of carbon nanotubes (LACNTs) were fabricated and controlled in polysiloxane-based nanocomposite films and the effects of the LACNTs on the thermal and electrical properties of the films were investigated. CNTs were dispersed by mechanical stirring and sonication in a prepolymer of polysiloxane. Homogeneous suspensions were cast on polyamide spacers and oriented by linear-assembly by applying DC and switching DC electric fields before the mixture became cross-linked. Densely packed LACNTs that fixed the composite film surfaces were fabricated with various structures and thicknesses that depended on the DC and switching DC conditions. Polymer nanocomposites with different LACNT densities exhibited enhanced thermal and electrical conductivities and high optical transmittances. They are considered promising structural materials for electronic sectors in automotive and aerospace applications

Synthesis and Characterisation of Metal Oxide Nanostructures Using Choline/Linear Alkyl Carboxylate Deep Eutectic Solvents

The synthesis of YBa2Cu3O7−x (YBCO or 123) was carried out via the use of a variety of deep eutectic solvents (DESs), all formed by the interaction of choline hydroxide (as the cation source) and alkyl carboxylic acids with CnH2n+1 ranging from n = 2 to n = 10, namely acetic acid, propionic acid, butyric acid, pentanoic acid, nonanoic acid, and decanoic acid, as providers of the anion, all prepared in equimolar solutions. The behaviour of the synthetic media and the resulting morphology displayed by the crystallite product, using different molar ratios of DESs (X):1 YBaCu metal nitrates mixes, with x values of 20 ≤ x ≤ 60, is also reported. Synthetic performance results show a tendency to generate higher total phase percentage of the desired crystal with the increase of the alkyl chain length of the carboxylic acid up to butyric acid (92% belonging to the metal oxide), after which no enhancement was observed. Furthermore, the synthetic performance of the remaining, i.e., DES formed with pentanoic acid to decanoic acid, displayed a constant decay in total desired phase percentage belonging to the metal oxide. Morphological results were also analysed for all DESs (X):1 YBaCu metal nitrates mixes, with x values of 20 ≤ x ≤ 60. Well defined plate-like particles were generally observed however, in some cases fused plate-like particles of significantly bigger size were observed

Nanotwin hardening in a cubic chromium oxide thin film

NaCl-type (B1) chromium oxide (CrO) has been expected to have a high hardness value and does not exist as an equilibrium phase. We report a B1-based Cr0.67O thin film with a thickness of 144 nm prepared by pulsed laser deposition as an epitaxial thin film on a MgO single crystal. The thin film contained a number of stacking faults and had a nanotwinned structure composed of B1 with disordered vacancies and corundum structures. The Cr0.67O thin film had a high indentation hardness value of 44 GPa, making it the hardest oxide thin film reported to date

Internal structure control of the TiO2 nanotubes and polysiloxane nanocomposites by nanosecond pulsed electric field

A facile technique has been introduced for incorporating TiO2 nanotubes (TNTs) in amorphous polysiloxane-based nanocomposite films and for linear and dense assembling of these TNTs (LATNTs) under application of nanosecond pulse electric field. The use of a nanosecond electrical pulse enables the application of high electric power without causing dielectric breakdown, which occurs when DC/AC electric field is used, and the formation of LATNTs which anchor the resulting composite film planes. The properties of the nanocomposites were investigated using X-ray micro CT scanning, digital micrographs, UV–vis spectroscopy and electrical resistivity measurements. More than 5.5-fold UV–vis transmittance improvement was obtained by the polymer composite containing LATNTs (TNT 5.0 wt%). Such a composite exhibited a decreased electric resistivity of 3.08 × 107 Ω m compared to the case for randomly distributed TNTs (3.25 × 108 Ω m)