Synthesis,characterization and antimicrobial activity of colloidal copper nanoparticles stabilized by cationic thiol polyurethane surfactants

Metal nanoparticles have attracted considerable interest particularly because of the size dependence of physical and chemical properties and its enormous technological potential. Among different metal nanoparticles, copper nanoparticles have attracted great attention because copper is one of the most key metals in new technology. Chemical methods are used to synthesize copper nanoparticles. Chemical reduction is the most frequently applied method for the preparation of stable, colloidal dispersions in organic solvents. In this paper, the new cationic thiol polyurethane surfactants with different alkyl chain length were synthesized (PQ10, PQ14 and PQ18). The chemical structure of the synthesized surfactants was confirmed using infra-red spectroscopy (IR) and proton nuclear magnetic resonance spectroscopy (¹HNMR). Copper nanoparticles colloidal solution of 40–80 nm diameters was prepared using sodium borohydride in aqueous solution at room temperature as reducing agent. The synthesized surfactants decrease the aggreegation of copper nanoparticles. The nanostructure of the synthesized surfactant with copper nanoparticles with diameters ranging from 31.5 to 10.3 nm was prepared and characterized using ultra violet spectrophotometer (UV), infra-red spectroscopy (IR) and transmission electron microscope (TEM). The results declare formation and stabilization of copper nanoparticle using synthesized cationic surfactants. Antimicrobial activity of the synthesized cationic surfactants and their nanostructure with copper nanoparticles were evaluated against pathogenic bacteria and fungi.     

Silica Nanoparticles with Proton Donor and Proton Acceptor Groups: Synthesis and Aggregation

The effects of precursor structure and polycondensation conditions on the properties of hybrid nanoparticles synthesized from organo-trimethoxysilanes were studied. Hybrid nanoparticles containing groups capable of forming hydrogen bonds were synthesized from functional derivatives of 3-aminopropyltrimethoxysilane. For the synthesis of phenylurea-functionalized organosilica nanoparticles different approaches to nanoparticle preparation were used. It was shown that the nature of the functional groups (proton-donor or proton-acceptor) affects the aggregation of silica nanoparticles. Also, the difference in behavior of nanoparticles prepared using surface modification and polycondensation was demonstrated for different pH, ionic strength and solvent polarity. As a result, by changing the pH of the solutions, it is possible to shift the aggregation pattern of these nanoparticles, such as the size of the initially formed aggregates.     

采用不同方法合成CuS纳米粒子研究

分别采用水热合成法及微乳液法制备了纳米CuS粒子。以醋酸铜和升华硫为原料配成稳定溶液,进行水热合成得到纳米CuS粒子;以表面活性剂十六烷基三甲基溴化铵(CTAB)、有机溶剂正庚烷、水和助表面活性剂正丁醇组成的W/O型微乳体系,在加热状态下合成纳米CuS粒子。并采用UV-VIS、XRD和TEM等分析手段对粉体进行了表征。     

Microwave polyol synthesis of Pt/CNTs catalysts: Effects of pH on particle size and electrocatalytic activity for methanol electrooxidization

Pt nanoparticles with different mean sizes supported on carbon nanotubes were synthesized by microwave heating ethylene glycol solutions of platinum salt with different pH in present of CNTs as supports. TEM examinations showed that Pt particles become smaller and more uniform when the synthesis pH increased from 3.4 to 9.2. The mean particle size was 5.8, 5.2, 3.4 and 2.7 nm when the synthesis pH was 3.6, 5.8, 7.4 and 9.2, respectively. The effects of the pH on Pt particle size and distribution were investigated. The pH was an important factor that influenced the particle size. Pt particles size could be thus selected by adjusting the synthesis solution pH. Pt/CNTs with suitable and uniform Pt particle size could be obtained. Electrochemical measurements showed that the Pt/CNTs catalyst prepared from the synthesis solution pH of 7.4 exhibited better performances for methanol electrooxidization than other samples.     

吐温和十二烷基硫酸钠复配修饰制备纳米铜研究

在一定温度的水溶液中,以硫酸铜为前驱体,抗坏皿酸（Vc）为还原剂,加入适量修饰剂,合成粒径和形貌可控的纯铜纳米粒子,并通过XRD射线衍射,扫描探针显微镜等检测手段对产品进行了表征。结果表明,修饰剂的加入对粒径大小、分布、形貌和晶型结构影响显著;制备的纳米铜颗粒为具有立方品型结构的球型颗粒,分散性较好,尺寸较为均匀,约为60～80nm。纳米铜颗粒表面形成了较薄的有机物质包覆层,它有效阻止了纳米铜粉在空气和水中的氧化和团聚,提高了纳米铜颗粒的分散性和稳定性。     

Particle size effects in the thermal conductivity enhancement of copper-based nanofluids

We present an analysis of the dispersion characteristics and thermal conductivity performance of copper-based nanofluids. The copper nanoparticles were prepared using a chemical reduction methodology in the presence of a stabilizing surfactant, oleic acid or cetyl trimethylammonium bromide (CTAB). Nanofluids were prepared using water as the base fluid with copper nanoparticle concentrations of 0.55 and 1.0 vol.%. A dispersing agent, sodium dodecylbenzene sulfonate (SDBS), and subsequent ultrasonication was used to ensure homogenous dispersion of the copper nanopowders in water. Particle size distribution of the copper nanoparticles in the base fluid was determined by dynamic light scattering. We found that the 0.55 vol.% Cu nanofluids exhibited excellent dispersion in the presence of SDBS. In addition, a dynamic thermal conductivity setup was developed and used to measure the thermal conductivity performance of the nanofluids. The 0.55 vol.% Cu nanofluids exhibited a thermal conductivity enhancement of approximately 22%. In the case of the nanofluids prepared from the powders synthesized in the presence of CTAB, the enhancement was approximately 48% over the base fluid for the 1.0 vol.% Cu nanofluids, which is higher than the enhancement values found in the literature. These results can be directly related to the particle/agglomerate size of the copper nanoparticles in water, as determined from dynamic light scattering.     

Electrosynthesis of Co,Ni and Zn ferrites nanoparticles in the presence of external magnetic field

Magnetic complex oxides of iron nanoparticles are among the most important materials that have been studied. They have been widely used in different areas such as electronic devices, information storage, biomedical areas, drug-delivery, catalyst, and wastewater treatment. In different applications of nanoparticles, the shape and size of particles are very important because the electrical, optical, and magnetic properties of the nanoparticles depend on their dimension. In this study, nanoparticles of cobalt, nickel, and zinc ferrites were synthesized in uniform size by an electrochemical technique. First, the anode was made electrochemically by depositing each metal of zinc, nickel, and cobalt on the iron sheet from the solutions of 0.1 M Co²⁺, Ni²⁺, and Zn²⁺ ions as the precursor. Then the electrosynthesis of ferrite nanoparticles was performed in a second electrochemical cell where the prepared electrode was anode and stainless steel (316L) was cathode in the electrolyte solution of CTAB 0.04 M. The optimized value of current density was applied to the electrochemical cell. After then the same synthesis was carried out in the magnetic field supplied by two magnets. The prepared nanoparticles were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic properties were investigated by vibrating sample magnetometer (VSM). The comparison of two samples prepared in the magnetic field and without it showed the average size of the samples synthesized in the magnetic field was in the narrower size distribution of 20–30 nm and the saturation magnetization of the nanoparticles increased in the magnetic field.     

In(acac)_3和Sn(acac)_2Cl_2的合成及表征

介绍了化学法制备氧化铟锡(ITO)纳米材料的两个重要合成原料In(acac)3和Sn(acac)2Cl2的合成方法。以InCl3·4H2O为原料,在pH值为9.0的柠檬酸溶液中制备In(acac)3;以SnCl4·5H2O与乙酰丙酮为原料,在甲苯溶剂中加热回流制备Sn(acac)2Cl2。通过IR、NMR、XRD检测手段对合成的产物进行表征分析。讨论了各种实验条件对合成反应的影响,总结出In(acac)3的最佳合成条件是:柠檬酸浓度为84 mmol·L-1,pH值为9.0;制取Sn(acac)2Cl2的最佳溶剂是甲苯。     

Exfoliation of copper hydroxysalt in water and the conversion of the exfoliated layers to cupric and cuprous oxide nanoparticles

P-aminobenzoate-intercalated copper hydroxysalt was prepared by coprecipitation at high pH (～12). As the pH was reduced to ～7 on washing with water, the development of partial positive charge on the amine end of the intercalated anion caused repulsion between the layers leading to delamination and colloidal dispersion of monolayers of copper hydroxysalt in water. The dispersed copper hydroxysalt monolayers were used as precursors for the synthesis of copper(I)/(II) oxide nanoparticles at room temperature. While the hydroxysalt layers yielded spindle-shaped CuO particles when left to stand, they formed hollow spherical nanoparticles of Cu(2)O when treated with an alkaline solution of ascorbic acid.     

棒状形貌纳米氧化锌的合成及其应用

以六水硝酸锌和氨水-氢氧化钠为原料,采用液相沉淀法制备出氧化锌纳米棒。研究了氨水的初始浓度、滴加速度以及加热方式对纳米氧化锌形貌和尺寸的影响。结果表明：在氨水初始浓度为5%（质量分数）、滴加速度为60 g/h,并采用两段加热（成核生长温度为60 ℃、陈化温度为80 ℃）的方式,合成的纳米氧化锌呈棒状形貌,分散均匀,长径比达到11。纳米氧化锌对大肠杆菌具有很好的抑菌效果。水性聚氨酯中加入1.5%（质量分数）的棒状形貌纳米氧化锌后,可吸收250～400 nm的紫外线,拉伸强度从2.7 MPa增加到4.5 MPa。     

碱式碳酸铜制备实验的探索

以废杂铜为原料,用浓硝酸浸出硝酸铜溶液,利用可控的封闭装置处理生成的NO2,减少其对大气的污染。用碳酸钠与硝酸铜溶液进行反应,反应温度为60～80℃,反应终点的pH=8.5左右,漂洗3次。通过元素分析、红外光谱分析、XRD等手段确定了该方法制备出高纯度的碱式碳酸铜。     

Influence of Copper Nanoparticles Concentration on the Properties of Poly(vinylidene fluoride)/Cu Nanoparticles Nanocomposite Films

In this study, the nanocomposite films of polyvinylidene fluoride/copper nanoparticles were prepared by mixing of copper nanoparticles in a solution of dimethylformamide and polyvinylidene fluoride. The prepared nanocomposites were investigated by fourier transform infrared spectroscopy and X-ray diffraction techniques, showed an obvious α- to β-phase transformation compared to pure PVDF. Scanning electron microscope micrographs showed spherulitic crystal structure of PVDF. The spherulitic morphology of the pure PVDF is maintained for the PVDF nanocomposites; the size of the spherulites decreased by increasing weight fraction of copper nanoparticles. The optical band gap values deduced from the UV–Visible absorption spectra were found to reduce from 4.77 eV in pure PVDF to 3.2 eV after embedding 1 wt% of copper nanoparticles. The surface resistivity values were decreased with increasing copper nanoparticles content. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA). TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to pure PVDF.     

Synthesis and characterization of a salt‐resisting superabsorbent based on poly(acrylic acid) with sodium tungstate as a crosslinker

A novel salt‐resistant superabsorbent polymer was synthesized by solution polymerization from the monomer acrylic acid (AA) with potassium persulfate as the initiator. Sodium tungstate was first employed as a crosslinker in the preparation to achieve a better crosslinked polymer (WPAA). In addition to the xerogel WPAA, sodium hydroxide and tris(2‐hydroxyethyl)amine (TEA) were introduced for the preparation of WPAA–sodium and WPAA–TEA hydrogels, respectively. The effect on the water absorbency of factors such as the reaction temperature, degree of neutralization of AA, and amounts of the crosslinker sodium tungstate and the initiator were investigated. The crosslinked xerogels were characterized with infrared spectroscopy. These crosslinked superabsorbent composites with sodium tungstate were characterized with thermogravimetric analysis and scanning electron microscopy. The water absorbencies of these superabsorbent composites in water and saline solutions were investigated. Results obtained from this study showed that under the same synthesis conditions, in comparison with superabsorbent composites with an aluminum salt as a crosslinker and styrene as a graft copolymer, the salt resistance of the superabsorbent composite synthesized with sodium tungstate as a crosslinker was obviously enhanced. Moreover, the WPAA–TEA xerogel had absorbency values of 223.6 and 81.9 g/g for distilled water and a 0.9 wt % NaCl solution, respectively, and it showed better salt resistance and a better water‐absorbing rate than the WPAA–sodium xerogel because of the modification with triethanolamine. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

CuO/H2O纳米流体的池沸腾传热及预测

通过络合-沉淀法合成氧化铜纳米颗粒,制备铜颗粒的直径在40～100 nm,晶型为正六面体。利用“两步法”制备水基氧化铜纳米流体。考察了不同质量分数纳米流体的热导率、接触角变化和加热表面颗粒沉积对核沸腾传热性能的影响,并利用可视化记录沸腾过程气泡行为。结果表明：在测试质量分数范围内,传热系数随热通量增加而增大,当质量分数达到0.1%时,强化率最大为146.1%。经过分析可知纳米流体的接触角度、热导率、颗粒沉积以及颗粒扰动对水基氧化铜纳米流体强化传热作用均有影响。通过高速摄像采集质量分数0.07%纳米流体沸腾过程验证结论的可靠性。并对纳米流体核沸腾传热过程建立气泡动力学经验模型,模型计算结果与实测值相对偏差在±10%以内。     

Continuous synthesis of monodispersed silver nanoparticles using a homogeneous heating microwave reactor system

Continuous synthesis of silver nanoparticles based on a polyol process was conducted using a microwave-assisted flow reactor installed in a cylindrical resonance cavity. Silver nitrate (AgNO(3)) and poly(N-vinylpyrrolidone) (PVP) dissolved in ethylene glycol were used respectively as a silver metal precursor and as a capping agent of nanoparticles. Ethylene glycol worked as the solvent and simultaneously as the reductant. Silver nanoparticles of narrow size distributions were synthesized steadily for 5 h, maintaining almost constant yield (>93%) and quality. The reaction was achieved within 2.8 s of residence time, although nanoparticles were not formed under this flow rate by conventional heating. A narrower particle size distribution was realized by the increased flow rate of the reaction solution. Nanoparticles of 9.8 nm average size with a standard deviation of 0.9 nm were synthesized at the rate of 100 ml h(-l).     

Synthesis and Characterization of Cadmium Selenide (CdSe) Nanoparticles Using Trigonal Selenium (t-Se) Nanorods as Selenium Source

Cadmium selenide (CdSe) nanoparticles were synthesized through colloidal method in aqueous medium using the reaction intermediates selenium nanorods as selenium source. Trigonal selenium nanorods (t-Se) were synthesized in water by the reduction method in the presence of sodium borohydride at 60?°C using sodium selenite (Na₂SeO₃) as selenium source. These selenium nanorods were further utilized to synthesis cadmium selenide nanoparticles at 100?°C in water. The synthesized nanorods and nanoparticles were characterized using XRD, SEM, TEM and XPS analysis. X-ray diffraction (XRD) analysis shown that the nanorods possess trigonal phase while the nanoparticles possess a cubic zinc blende structure. Scanning electron microscope (SEM) analysis of the prepared hexagonal shaped nanorods reveals the diameter of the nanorods are about 150 nm. Transmission electron microscopy (TEM) analysis shows the size of the synthesized CdSe nanoparticles are about 4–8 nm. X-ray photoelectron spectroscopy (XPS) analysis illustrates the presence of respective elements Cd, Se with its corresponding oxidation states. The activity of nano selenium rods in aqueous solution during the conversion of cadmium selenide nanoparticles was discussed.     

四氯化硅液相鼓泡法制备纳米白炭黑工艺研究

以多晶硅副产物四氯化硅为原料,氨水为中和剂,十二烷基苯磺酸钠为改性剂,在水-醇-氨体系中利用液相鼓泡法制备纳米白炭黑,并采用IR、XRD、SEM、TEM对纳米白炭黑晶体结构、形貌、分散性及粒径进行表征。研究了醇水比、氨水用量、分散剂种类及用量、双氧水加入量等因素对纳米白炭黑分散性及粒径的影响。纳米白炭黑最佳制备工艺条件：体系总体积为70 mL,V（水）∶V（醇）∶V（氨）=38∶15∶12,六偏磷酸钠加入量为1.5%（质量分数）,双氧水用量为5 mL。IR、XRD表征结果表明产品为无定形二氧化硅;SEM、TEM表征结果表明纳米白炭黑粒径约100 nm且分散较好。     

An efficient ligand- and copper-free Sonogashira reaction catalyzed by palladium nanoparticles supported on pectin

A novel and green procedure for synthesis of Palladium nanoparticles (2–6 nm) supported on pectin, as a reductant and ligand is described. The synthesized catalyst was further successfully explored in copper, ligand- and amine-free Sonogashira–Hagihara coupling of various aryl iodides, bromides and chlorides as well as heteroaryl halides with phenylacetylene under aerobic conditions. It was found that the catalyst exhibited a high activity and selectivity for the Sonogashira–Hagihara reaction. The catalyst can be recovered and recycled by a simple filtration of the reaction solution with some decrease in catalytic activity.     

Fabrication and characterization of NiO nanoparticles by precipitation from aqueous solution

Present work involves synthesis of NiO nanoparticles using chemical homogeneous precipitation (CHP) method as a facile procedure. Ammonia as a complex agent was used in this method. Effects of different types of complexation-precipitation methods on the crystallinity and morphology of nanoparticles were investigated. NiO particles were prepared by direct precipitation method from NiSO₄ solution to compare crystallinity and morphology of NiO particles with particles obtained via complexation-precipitation methods. Our major intent was to investigate the effect of complex agent on the crystallization and growth of NiO nanoparticles. Results showed that the best condition for synthesizing spherical NiO shape was using NaOH as decomposing agent, of which the consequence was more uniformity and spherical nanoparticles with a diameter in the range of 40–60 nm. The size of the nickel oxide and nickel hydroxide nanoparticles was estimated by X-ray powder diffraction (XRD) pattern. The chemical structure information of the particles was studied by Fourier transform infrared (FT-IR) spectroscopy. Spherical, elliptical, sheet or flowerlike shapes were detected by field emission scanning electron microscopy (FESEM) analysis. Results showed that by the use of ammonia as complex agent, crystalline state and particles size distribution of NiO nanoparticles improved.     

Synthesis and characterization of novel copper/polyaniline nanocomposite and application as a catalyst in the Wacker oxidation reaction

Copper nanoclusters were synthesized by a chemical reduction of an aqueous copper salt solution by sodium borohydride. A polyaniline nanocomposite containing copper nanoclusters was prepared by polymerizing a monomer aniline hydrochloride solution containing the copper nanoclusters using ammonium persulfate as an oxidizing agent. The synthesized nanocomposite was characterized using various techniques such as UV‐visible spectroscopy, FTIR spectroscopy, X‐ray diffraction (XRD), and transmission electron microscopy (TEM). The presence of copper was confirmed by XRD and the size of the copper clusters was found to be ～53 nm, which is in good agreement with that obtained from the TEM. The synthesized nanocomposite was used to serve as a catalyst in a Wacker oxidation reaction for the conversion of 1‐decene to 2‐decanone in the presence of molecular oxygen. The formation of 2‐decanone was confirmed using GC‐MS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2412–2417, 2003