Shape Persistent,Highly Conductive Ionogels from Ionic Liquids Reinforced with Cellulose Nanocrystal Network

Shape-persistent, conductive ionogels where both mechanical strength and ionic conductivity are enhanced are developed using multiphase materials composed of cellulose nanocrystals and hyperbranched polymeric ionic liquids (PILs) as a mechanically strong supporting network matrix for ionic liquids with an interrupted ion-conducting pathway. The integration of needlelike nanocrystals and PIL promotes the formation of multiple hydrogen bonding and electrostatic ionic interaction capacitance, resulting in the formation of interconnected networks capable of confining a high amount of ionic liquid (≈95 wt%) without losing its self-sustained shape. The resulting nanoporous and robust ionogels possess outstanding mechanical strength with a high compressive elastic modulus (≈5.6 MPa), comparable to that of tough, rubbery materials. Surprisingly, these rigid materials preserve the high ionic conductivity of original ionic liquids (≈7.8 mS cm⁻¹), which are distributed within and supported by the nanocrystal network-like rigid frame. On the one hand, such stable materials possess superior ionic conductivities in comparison to traditional solid electrolytes; on the other hand, the high compression resistance and shape-persistence allow for easy handling in comparison to traditional fluidic electrolytes. The synergistic enhancement in ion transport and solid-like mechanical properties afforded by these ionogel materials make them intriguing candidates for sustainable electrodeless energy storage and harvesting matrices.     

Compliance error compensation technique for parallel robots composed of non-perfect serial chains

The paper presents the compliance errors compensation technique for over-constrained parallel manipulators under external and internal loadings. This technique is based on the non-linear stiffness modeling which is able to take into account the influence of non-perfect geometry of serial chains caused by manufacturing errors. Within the developed technique, the deviation compensation reduces to an adjustment of a target trajectory that is modified in the off-line mode. The advantages and practical significance of the proposed technique are illustrated by an example that deals with groove milling by the Orthoglide manipulator that considers different locations of the workpiece. It is also demonstrated that the impact of the compliance errors and the errors caused by inaccuracy in serial chains cannot be taken into account using the superposition principle.     

Annealing effects on microstructure and mechanical properties of sputtered multilayer Cr(1 − x)AlxN films

Multilayer Cr_(1 − x)Al_xN films with a total thickness of 2 μm were deposited on high-speed steel by medium frequency magnetron sputtering from Cr and Al-Cr (70 at.% Al) targets. The samples were annealed in air at 400 °C, 600 °C, 800 °C and 1000 °C for 1 hour. Films were characterized by cross-sectional scanning electron microscopy and X-ray diffraction analysis. The grain size of the as-deposited multilayer films is about 10 nm, increasing with the annealing temperature up to 100 nm. Interfacial reactions have clearly changed at elevated annealing temperatures. As-deposited films' hardness measured by nanoindentation is 22.6 GPa, which increases to 26.7 GPa when the annealing temperature goes up to 400 and 600 °C, but hardness decreases to 21.2 GPa with further annealing temperature increase from 600 to 1000 °C. The multilayer film adhesion was measured by means of the scratch test combined with acoustic emission for detecting the fracture load. The critical normal load decreased from 49.7 N for the as-deposited films to 21.2 N for the films annealed at 1000 °C.     

Synthesis,structure and properties of heavily Mn-doped perovskite-type SrTiO3 nanoparticles

Cubic perovskite SrTi_1−xMn_xO₃ nanopowders with x = 0–0.5, which is much higher than the conventionally believed Mn incorporation limit, and particles sizes 10–80 nm have been successfully synthesized using the citrate sol–gel method. The crystalline structure, the morphology, the chemical composition and the lattice constant behavior versus the annealing temperature and the Mn concentration have been characterized using X-ray diffraction, scanning electron microscopy and proton-induced X-ray emission techniques. Studies of Raman light scattering and the magnetic properties revealed the activation of the TO2 polar mode and the magnetic ordering effects at low temperatures. Such features are treated as possible evidence of non-d⁰ Mn-driven transition to a polar phase with multiferroicity in heavily concentrated perovskite SrTi_1−xMn_xO₃ nanopowders.     

Hydrosilylation of Internal Alkynes Catalyzed by Tris‐ Imidazolium Salt‐Stabilized Palladium Nanoparticles

Palladium nanoparticles stabilized with tris‐imidazolium tetrafluoroborates catalyze the stereoselective hydrosilylation of internal alkynes in a dry inert atmosphere to give (E)‐vinylsilanes in excellent yields. In the presence of controlled amounts of water a transfer hydrogenation reaction takes place with the formation of (Z) ‐ alkenes or the corresponding alkanes.

     

Synthesis of random copolymers of styrene and arylamino substituted styrenes and their sensitivities towards nitroaromatics

Random copolymers of styrene and substituted styrenes bearing arylamino substituents as fluorophore units have been obtained. Their photophysical properties have been investigated by measuring absorption and emission spectra as in solutions as solid-state. All copolymers proved to possess absolute quantum yields up to 0.39 in solution and up to 0.05 in solid-state, depending on their fluorophore substituents. Fluorescence studies have shown that these copolymers show a highly sensitive response towards a diversity of nitroaromatic compounds, both in solutions and in a vapor phase. The detection limits for these compounds towards model nitroaromatic explosives in dichloromethane solution proved to be in the range from 10⁻⁶ to 10⁻⁷ mol/L. The fluorescent materials prepared by electrospinning of synthesized copolymers have been evaluated as sensor materials for detecting nitrobenzene vapor for our hand-made sniffer with detection limits of 0.5 ppm during 100-s exposure to the vapor.     

Bromination of [60]Fullerene. I. High-Yield Synthesis of C60Brx (x=6, 8, 24)

The systematic study of the bromination of C₆₀ was performed under various experimental conditions. Application of some chloroarenes as reaction media resulted in the high-yield (70-96%) selective synthesis of C₆₀Br₆ and C₆₀Br₈. Direct bromination of fullerene yielded either C₆₀Br₈, C₆₀Br₁₄, or C₆₀Br₂₄ depending on the reaction time. Possible pathways of bromination of C₆₀Br₈ were analyzed using semiempirical (AM1) calculations, two most probable molecular structures are conjectured for the first isolated C₆₀Br₁₄.     

Sol–Gel Assisted Inkjet Hologram Patterning

Hereby, it is presented for the first time a method of producing holographic text and images using inkjet printing. For this purpose, colorless TiO₂ ink with a high refractive index is used and deposited on top of exposed poly(ethylene terephthalate)‐based microembossed paper by an inkjet printer. Nanoscale coating the paper containing printed text or graphics with transparent polymers or lacquers provides an optical effect of selective preservation of the holographic pattern. The resulting image is preserved only at the site of the colorless ink with a high refractive index from an inkjet printer, allowing to quickly generate any image with a holographic effect. Achieving these results has succeeded through the use of a colloidal dispersion of nanocrystalline titania with a refractive index of 1.75 ± 0.08 in the entire visible range, which meets inkjet rheological requirements. It is shown that the diffraction effect and optical transparency in the visible region are fully preserved. For the first time, it is demonstrated the importance of chemically prepared nanomaterials and nanostructures for an application in the field of holography.     

Rhodium Nanoflowers Stabilized by a Nitrogen‐Rich PEG‐Tagged Substrate as Recyclable Catalyst for the Stereoselective Hydrosilylation of Internal Alkynes

Morphology and size controllable rhodium nanoparticles stabilized by a nitrogen‐rich polyoxyethylenated derivative have been prepared by reduction of RhCl₃ with NaBH₄ in water at room temperature and fully characterized. The flower‐like Rh NPs are effective and recyclable catalysts for the stereoselective hydrosilylation of challenging internal alkynes and diynes, affording the (E)‐vinylsilanes in quantitative yields for a wide range of substrates. The insolubility of the nanocatalyst in diethyl ether allows its easy separation and recycling.