Enhanced ethanol sensing properties of WO3 modified TiO2 nanorods

Pristine and WO₃ decorated TiO₂ nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO₂ NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO₂ NRs and thermally oxidised to obtain WO₃ nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures. Experimental results demonstrated that the heterostructure has better sensor response toward ethanol at 200 °C. Enhanced sensing properties are attributed to the heterojunction formation by decorating TiO₂ NRs with WO₃.     

A Versatile Strategy to Synthesize Perfluoropolyether‐Based Thermoplastic Fluoropolymers by Alkyne‐Azide Step‐Growth Polymerization

Perfluoropolyether (PFPE)‐based thermoplastic fluoropolymers are synthesized by A₂ + B₂ step‐growth polymerization between PFPE‐diyne and fluorinated diazides. This versatile method allows synthesizing PFPE‐based materials with tunable physicochemical properties depending on the exact nature of the fluorinated segment of the diazide precursor. Semicrystalline or amorphous materials endowed with high thermostability (≈300 °C under air) and low glass transition temperature (≈−100 °C) are obtained, as confirmed by differential scanning calorimetry, thermogravimetry, and rheometry. Step‐growth polymerizations can be copper‐catalyzed but also thermally activated in some cases, thus avoiding the presence of copper residues in the final materials. This strategy opens up new opportunities to easily access PFPE‐based materials on an industrial scale. Furthermore, a plethora of developments can be envisioned (e.g., by adding a third trifunctional component to the formulations for the synthesis of PFPE‐based elastomers).

     

Highly selective synthesis of catalytically active monodisperse rhodium nanocubes

Monodisperse sub-10 nm Rh nanocubes were synthesized with high selectivity (>85%) by a seedless polyol method. The {100} faces of the Rh NCs were effectively stabilized by chemically adsorbed Br- ions from trimethyl(tetradecyl)ammonium bromide (TTAB). This simple one-step polyol route can be readily applied to the preparation of Pt and Pd nanocubes. Moreover, the organic molecules of PVP and TTAB that encapsulated the Rh nanocubes did not prevent catalytic activity for pyrrole hydrogenation and CO oxidation.     

Phenolic compounds,essential oil composition,and antioxidant activity of Angelica purpurascens (Avé-Lall.) Gill

In this study, methanol extracts (MEs) and essential oil (EO) of Angelica purpurascens (Avé-Lall.) Gill obtained from different parts (root, stem, leaf, and seed) were evaluated in terms of antioxidant activity, total phenolics, compositions of phenolic compound, and essential oil with the methods of 2,2-azino-bis(3ethylbenzo-thiazoline-6-sulfonic acid (ABTS•⁺), 2,2-diphenyl-1-picrylhydrazil (DPPH•) radical scavenging activities, and ferric reducing/antioxidant power (FRAP), the Folin–Ciocalteu, liquid chromatography−tandem mass spectrometry (LC−MS/MS), and gas chromatography-mass spectrometry (GC−MS), respectively. The root extract of A. purpurascens exhibited the highest ABTS•⁺, DPPH•, and FRAP activities (IC₅₀: 0.05 ± 0.0001 mg/mL, IC₅₀: 0.06 ± 0.002 mg/mL, 821.04 ± 15.96 µM TEAC (Trolox equivalent antioxidant capacity), respectively). Moreover, EO of A. purpurascens root displayed DPPH• scavenging activity (IC₅₀: 2.95 ± 0.084 mg/mL). The root extract had the highest total phenolic content (438.75 ± 16.39 GAE (gallic acid equivalent), µg/mL)). Twenty compounds were identified by LC−MS/MS. The most abundant phenolics were ferulic acid (244.39 ± 15.64 μg/g extract), benzoic acid (138.18 ± 8.84 μg/g extract), oleuropein (78.04 ± 4.99 μg/g extract), and rutin (31.21 ± 2.00 μg/g extract) in seed, stem, root, and leaf extracts, respectively. According to the GC−MS analysis, the major components were determined as α-bisabolol (22.93%), cubebol (14.39%), α-pinene (11.63%), and α-limonene (9.41%) among 29 compounds. Consequently, the MEs and EO of A. purpurascens can be used as a natural antioxidant source.     

Dispersion of silica nanoparticles bearing perfluorohexyl units into fluorinated copolymers

This study aims at determining the compatibility behavior of nanoparticles surface with fluorinated matrices to obtain a homogenous dispersion and better composites properties. First, modified silica nanoparticles by C₆F₁₃I and C₆F₁₃‐C₂H₄‐SH led to various fluorinated silica of different massic concentrations and grafting rates. The dispersion of these nanoparticles (in 5 wt %) into molten poly(VDF‐co‐HFP) and poly(TFE‐co‐HFP) matrices were studied as well as the hydrophobic, mechanical, and thermal properties of both fluorinated copolymers and resulting composites. In both series, the storage modulus of nanocomposites increased while the melting (T_m) and decomposition (T_10%) temperatures varied with the polymer matrix. They increased for poly(VDF‐co‐HFP) composites (T_m= 134 to 144 °C and T_10%= 441 to 464 °C) but decreased for poly(TFE‐co‐HFP) nanocomposites (T_m= 276 to 268 °C and T_10%= 488 to 477 °C). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1512–1522