Polymer-supported metals and metal oxide nanoparticles: synthesis,characterization, and applications

Metal and metal oxide nanoparticles exhibit unique properties in regard to sorption behaviors, magnetic activity, chemical reduction, ligand sequestration among others. To this end, attempts are being continuously made to take advantage of them in multitude of applications including separation, catalysis, environmental remediation, sensing, biomedical applications and others. However, metal and metal oxide nanoparticles lack chemical stability and mechanical strength. They exhibit extremely high pressure drop or head loss in fixed-bed column operation and are not suitable for any flow-through systems. Also, nanoparticles tend to aggregate; this phenomenon reduces their high surface area to volume ratio and subsequently reduces effectiveness. By appropriately dispersing metal and metal oxide nanoparticles into synthetic and naturally occurring polymers, many of the shortcomings can be overcome without compromising the parent properties of the nanoparticles. Furthermore, the appropriate choice of the polymer host with specific functional groups may even lead to the enhancement of the properties of nanoparticles. The synthesis of hybrid materials involves two broad pathways: dispersing the nanoparticles (i) within pre-formed or commercially available polymers; and (ii) during the polymerization process. This review presents a broad coverage of nanoparticles and polymeric/biopolymeric host materials and the resulting properties of the hybrid composites. In addition, the review discusses the role of the Donnan membrane effect exerted by the host functionalized polymer in harnessing the desirable properties of metal and metal oxide nanoparticles for intended applications.     

Novel porous CuO microrods: synthesis,characterization, and their photocatalysis property

Porous copper oxide microrods have been synthesized via calcining copper glycinate monohydrate microrod precursor which was prepared in mild conditions without any template or additive. Several techniques, such as X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller (BET) N₂ adsorption–desorption analyses, were used to characterize the structure and morphology of the products. Scanning electron microscopy (SEM) analyses show that the precursor consists of a large quantity of uniform rod-like micro/nanostructures with typical lengths in the range of 25–40 µm and diameters in the range of 0.1–0.35 µm. The microrod-like precursors transformed into porous microrod products after calcination at 450 °C in flow air for 2 h. The BET surface area of the porous CuO microrods was calculated to be 8.5 m² g⁻¹. In addition, the obtained porous CuO microrods were used as catalysts to photodegrade rhodamine B (RhB), methyl orange, methylene blue, eosin B, and p-nitrophenol. Compared with commercial CuO powders, the as-prepared porous CuO microrods exhibit superior properties on photocatalytic decomposition of RhB due to their porous hierarchical structures.     

Solutions of Laplace's equation with simple boundary conditions,and their applications for capacitors with multiple symmetries

We find solutions of Laplace's equation with special boundary conditions, using a general curvilinear system of coordinates. We call this purely geometrical solutions Basic Harmonic Functions (BHF's). From them we obtain more general solutions with arbitrary constant values on the boundaries. Further, the BHF's are used to obtain the capacitance of many electrostatic configurations of conductors. Applications in complex geometries are given. Finally, expressions for electric fields between two conductors and surface charge densities are obtained in terms of generalized curvilinear coordinates. The present method can be extrapolated to other linear homogeneous differential equations.     

液相等离子体及其在纳米材料制备中的应用

液相等离子体是冷等离子体的一个新分支,具有温度低、传质传热快、常压操作、反应活性高等特点。基于液相等离子体的过程强化技术在纳米材料制备、挥发性有机物降解、杀菌消毒、化学合成等领域有广泛的应用前景。以液相等离子体中纳米材料的制备为研究对象,介绍了反应体系可能存在的活性粒子、检测方法和反应机理;对常见的反应器结构进行归纳整理,按照放电是否在电解液内部进行将其分为非浸没式和浸没式液相等离子体两大类,并列举了几种典型的反应器结构;介绍了几类利用液相等离子体技术制备纳米材料的典例,并对该领域的研究现状做了总结;对该领域亟需解决的问题与发展方向进行讨论与展望。     

Influences of space charge and electrode on the electrical transport through (Ba,Sr)TiO3 thin film capacitors

The combined model of thermionic emission and carrier drift-diffusion is derived to simulate the electrical transport through BST thin film capacitors. In the model the field-dependent permittivity is obtained from the derivative of the polarization distinguished with the traditional characterization. The simulated currents show the hysteresis. The influences of space charges and electrode materials on the current density-applied voltage characteristics have been studied. The simulation results suggest that the current densities can be greatly influenced by the space charges at the cathode interface and the barrier height at the electrode/BST interface. It is expected that this work can provide some useful guidelines to the design and performance improvement of BST thin film capacitors and other BST thin film devices.     

Bifunctional Au-nanorod@Fe3O4 nanocomposites: synthesis, characterization, and their use as bioprobes

Membrane gas separation technology has been rapidly growing for industrial applications such as air separation, carbon dioxide (CO₂) separation from natural gas production, hydrogen separation, etc. Needs for CO₂ separation are increasing as carbon capture technology has been recognized as an essential part when combating the global warming issue. Membrane gas separation technology deals with mass transport phenomena through the membrane engineered on a sub-nanoscale controlling transport properties of small gas molecules such as CO₂, N₂, O₂, H₂, etc. In this review, we will report on the recent developments in capture technologies utilizing various membranes including nano-engineered thermally rearranged (TR) polymers. TR polymer membranes show high gas permeability as well as good separation properties, especially in CO₂ separation processes such as from post-combustion flue gas and natural gas sweetening.     

One-pot synthesis of SnS nanorods and their lithium storage properties

Tin sulfide (SnS) nanorods have been synthesized through a facile template-free solvothermal route and characterized using XRD, SEM, and TEM. Results indicate that the as-prepared SnS nanorods are 30–100 nm in diameter and ~1,000 nm in length. When used as an anode material, the nanorods exhibit enhanced lithium ion storage properties with high reversible capacity and good cyclic performance. The superior electrochemical performance can be ascribed to the unique one-diamensional nanostructure, which restrains volume expansion of the nanorods and reduces lithium ion diffusion path length efficiently.     

Silver-doped silver vanadate glass composite electrolyte: structure and an investigation of electrical properties

Ionics - Structural and electrical properties of the ternary ionic–electronic conducting glass system xAgI–(1 − x)[0.67Ag2O–0.33V2O5], where x = 0.4,...     

Enzymatic synthesis of multi-component copolymers and their structural characterization

The use of enzymes in synthetic applications has increased dramatically in the recent years and the field of polymer science is part of this trend. Synthesis of a variety of polymers using lipase catalyzed (Candida antarctica) polymerization reactions has led to a variety of new materials with interesting properties in our laboratories. This paper describes the synthesis of multi-component polyesters and mixed polymers having polyester and polyamide linkages under solvent-less conditions using Candida antarctica lipase B. The effect of a third component, i.e. a series of 1,omega-alkanediols (1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol and 1,16-hexadecanediol) on the copolymerization reaction of dimethyl 5-hydroxyisophthalate with poly(ethylene glycol 600) has been studied and the mechanism for the incorporation of the third component is proposed. We have also studied the effect of different functional groups during terpolymerization reaction of dimethyl 5-hydroxyisophthalate with poly(ethylene glycol) by adding a third component having different functionalities (1,6-hexanediol, 1,6-hexanediamine or 1,6-hexanedithiol) and compared the effect of hydroxyl, amine and thiol groups on the polymerization reactions.     

Growth,structural, spectral,thermal, electrical and optical characterization of a novel optical material: Triethanolamine picrate single crystals for optical applications

The Triethanolamine picrate (TEAP) single crystal was grown by slow evaporation technique. The grown crystal crystallizes in monoclinic system and P2_1/C is the space group determined by Single crystal X-Ray diffraction method. The vibrational modes and functional groups were elucidated from Fourier Transform InfraRed (FTIR) spectra and Fourier Transform Raman (FT-Raman) spectra. The Ultraviolet - Visible (Uv-Vis) studies accomplished the excitation wavelength of the grown crystal is around 203 nm and 354 nm and it is suitable to exhibit second harmonic generation signal. From the absorption data, remarkable optical properties such as optical band gap energy, extinction coefficient were evaluated. The mechanical strength of the grown crystal was examined by Vickers micro hardness test. The temperature of decomposition was confirmed by Thermo Gravimetric / Differential Thermal Analysis (TG/DTA). Kurtz and Perry technique were confirmed the Non-Linear Optics (NLO) property of the crystal. The electrical properties were explained using Dielectric studies.     

Zinc impregnated cellulose nanocomposites: Synthesis,characterization and applications

Nanocomposite materials have broad applicability due to synergistic effect of combined components. In present investigation, cellulose isolated from citrus peel waste is used as a supporting material; impregnation of zinc oxide nanoparticles via co-precipitation method. The characterization of nano composite is carried out through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and Thermo-gravimetric analysis (TGA) resulting less than 10 µm cellulose fiber and approx. 50 nm ZnO NPs. Zinc oxide impregnated cellulose (ZnO–Cel) exhibited significant bacterial devastation property when compared to ZnO NPs or Cellulose via disc diffusion and colony forming unit methods. In addition, the ZnO–Cel exhibited significant total antioxidant, and minor DPPH free radical scavenging and total reducing power activities. The nano composite also showed time dependent increase in photocatalytic by effectively degrading methylene blue dye up to 69.5% under sunlight irradiation within 90 min. The results suggest effective utilization of cellulose obtained from citrus waste and synthesis of pharmacologically important nano-composites that can be exploited in wound dressing; defence against microbial attack and healing due to antioxidative property, furthermore can also be used for waste water treatment.     

New porphyrins: synthesis,characterization, and computational studies

Molecular Diversity - New trans-A2B2-porphyrins substituted at phenyl positions were synthesized from 4-methylphthalic acid as a starting material through sequential multistep reactions. These...     

Copper sulfide nanotubes: facile, large-scale synthesis, and application in photodegradation

Large-scale synthesis of copper sulfide (CuS) nanotubes with uniform size could be achieved via a facile hydrothermal method. The whole process could be adjusted to prepare CuS with different nanostructures by simply changing the concentration of NaOH or reaction temperature while keeping other conditions unchanged. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Photoluminescence (PL) spectroscopy were used to characterize the products. The as-prepared CuS nanotubes showed good photocatalytic activity of degrading eosin Y under UV-vis light irradiation, which indicated the potential application of the CuS nanotubes in eliminating pollution and environmental protection.