Selective synthesis of copper microsheets and ultralong microwires via a surfactant assisted hydrothermal process

The surfactant assisted hydrothermal process for selective preparation of copper nanosheets and ultralong microwires by reducing Cu²⁺ with 2-(bis-phosphonomethylamino)propionic acid (dpc) under the action of cetyltrimethylammonium bromide (CTAB) or polyvinyl pyrrolidine (PVP) is presented. X-ray powder diffraction (XRD) and energy dispersive X-ray analysis (EDX) indicate that the products are pure Cu of cubic phase. The effects of starting material concentration and reaction time on morphology of nanosheets have been studied by scanning electron microscopy (SEM). The presence of CTAB and PVP as capping agents is identified by EDX, transmission electron microscopy (TEM) and FT-IR. The possible growth process for ultralong microwires was studied by stopping the growth at a series of intermediate morphology stages based on SEM observations. Optical properties of Cu nanosheets and ultralong microwires were studied by UV-Vis spectrophotometry.     

Facile and green methodology for surface‐grafted Al2O3 nanoparticles with biocompatible molecules: preparation of the poly(vinyl alcohol)@poly(vinyl pyrrolidone) nanocomposites

The present work describes preparation of modified alumina with biocompatible, water soluble, and treating agents such as citric acid and ascorbic acid. Also, the influence of the modified nanoparticles (NPs) into the blend of poly(vinyl alcohol)@poly(vinyl pyrrolidone) (50/50) matrix was studied. At first, citric acid and ascorbic acid as environmental friendly agents were grafted on the surface of Al₂O₃ NPs. Then, nanocomposites (NCs) with different amounts of modified Al₂O₃ NPs were prepared via a simple ultrasonic method. The characterizations of the molecular structure of the NCs specified that chemical and physical interactions happened between inorganic and organic counterparts. The mutual effect of modified NPs into the polymer matrix was investigated on the structural, interfacial interaction, thermal stability, and optical properties. The results from morphological characterization confirmed changes in morphology of poly(vinyl alcohol) and poly(vinyl pyrrolidone) after loading NPs. Uniform dispersion of modified spherical Al₂O₃ NPs powders into the matrix of 50/50 polymers was detected by field emission scanning electron microscopy and energy‐dispersive X‐ray. Adding M‐NPs into the polymer matrix expressively improved the thermal stability of NCs. Peaks in ultraviolet–visible spectra were shifted to the higher absorption. Copyright © 2017 John Wiley & Sons, Ltd.     

Benzyltriphenylphosphonium Chlorochromate: A Mild and Novel Reagent for Oxidation of Benzylic and Allylic Alcohols Under Non-Aqueous and Aprotic Conditions or Microwave Conditions

This paper describes the oxidation of benzylic and allylic alcohols under non-aqueous and aprotic conditions or microwave conditions using benzyltriphenylphosphonium chlorochromate (1) PhCH₂PPh₃CrO₃.HCl which has been prepared by mixing an aqueous solution of benzyltriphenylphosphonium chloride with CrO₃ in 6 N HCl at room temperature. This reagent is stable orange powder which may be stored for months without loss of its activity. This compound is readily soluble in organic solvents such as acetonitrile, chloroform and dichloromethane and slightly soluble in carbon tetrachloride, ether and hexane. the oxidation under microwave conditions is much more faster.     

The effects of reactive organoclay on the thermal, mechanical, and microstructural properties of polymer/layered silicate nanocomposites based on chiral poly(amide-imide)s

Considering the importance of the nanocomposites, the present work focuses on some new hybrid materials prepared by introducing reactive organoclay (OC) into the chiral poly(amide-imide) (PAI) matrix. At first, Cloisite Na⁺ was modified with protonated l-isoleucine amino acid. Then, PAI containing phenylalanine was synthesized via solution polycondensation of chiral diacid chloride with 4,4′-diaminodiphenylsulfone and was characterized with Fourier transform infrared (FTIR) and ¹H NMR techniques. At last, PAI/OC nanocomposite films containing 2, 5, 10, and 15 % of OC were prepared via solution intercalation method. The effect of OC dispersion and the interaction between OC and polymer chains on the properties of nanocomposites were investigated using FTIR, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, tensile testing of thin films, and thermogravimetry analysis techniques. The thermal stability of hybrids such as the decomposition temperature and mass residue at 800 °C was improved. Mechanical data indicated improvement in the tensile strength of the nanocomposites with OC loading up to 10 wt%. The transparency of the hybrid films was investigated by means of UV–Vis spectra.     

Insertion of fluorophore dyes between Cloisite Na+ layered for preparation of novel organoclays

The aim of this study was to obtain novel photo-functional organomontmorillonites from the intercalation reaction of Cloisite Na⁺ and fluorescent dyes of auramine O, and safranin T in an aqueous solution. The insertion of surfactants in the interlamellar space of nanoclay was followed by Fourier transform infrared spectroscopy and X-ray measurements. An X-ray diffraction analysis established that incorporation of the organic dye cations into the Cloisite Na⁺ expands remarkably the mineral interplanar distances from 1.17 to 1.83–1.97 nm. Field emission scanning electron microscopy was used to study the morphology of the synthesized organoclays. The thermal behavior of the novel hybrid materials was investigated by thermogravimetric analysis and the results show that the organo modified clays verify stepwise decomposition corresponding to initial weight loss from residual water desorption, followed by decomposition of the fluorescent dyes and the dehydroxylation of structural water of the clay layers. Fluorescence properties of the cationic dyes, auramine O, and safranin T incorporated in the clay have significant differences from their behavior in organic solvents and water and the results show that both dyes exhibit a significant fluorescence emission at room temperature when adsorbed in clay.     

Opportunities and Challenges in the Use of TiO2 Nanoparticles Modified with Citric Acid to Synthesize Advanced Nanocomposites Based on Poly(amide-imide) Containing N,N′-(Pyromellitoyl)-bis-L-leucine Segments

In this study, the goal was the preparation, characterization, and surface morphology of poly(amide-imide)/TiO₂-citric acid nanocomposites (PAI/TiO₂-CA NCs). Owing to the high surface energy and tendency for agglomeration, the surface of TiO₂ nanoparticles was modified with citric acid. Then poly(amide-imide) was synthesized by direct polycondensation reaction of N,N′-(pyromellitoyl)-bis-L-leucine diacid with 4,4′-diaminodiphenylmethane by triphenyl phosphite and tetra-n-butylammonium bromide as a green medium. The attained polymer and modified TiO₂ nanoparticles were used to prepare PAI/TiO₂-CA NCs through ultrasonic irradiation. The resulting PAI/TiO₂-CA NC was characterized with FT-IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis.