Ultrasmall Ag nanocrystals supported on chitosan/PVA nanofiber mats with bifunctional properties

Bifunctional nanofiber mats consisting of chitosan (CS), poly(vinyl alcohol) (PVA), and silver nanocrystals (Ag NCs) have been fabricated by a facile electrospinning method. The formation and presence of Ag NCs supported on CS/PVA nanofibers are confirmed by ultraviolet‐visible spectroscopy and X‐ray diffraction. The morphology of the samples is characterized by transmission electron microscopy and scanning electron microscopy. The prepared Ag NCs/CS/PVA nanofiber mats show pronounced antibacterial activity against Escherichia coli and excellent filtration property for suspended particulate matter (SPM) particles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46504.     

Synthesis and characterization of polyethylene glycol mediated silver nanoparticles by the green method

The roles of green chemistry in nanotechnology and nanoscience fields are very significant in the synthesis of diverse nanomaterials. Herein, we report a green chemistry method for synthesized colloidal silver nanoparticles (Ag NPs) in polymeric media. The colloidal Ag NPs were synthesized in an aqueous solution using silver nitrate, polyethylene glycol (PEG), and β-D-glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag NPs were studied at different reaction times. The ultraviolet-visible spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The Ag NPs were characterized by utilizing X-ray diffraction (XRD), zeta potential measurements and Fourier transform infrared (FT-IR). The use of green chemistry reagents, such as glucose, provides green and economic features to this work.     

Silver-zinc oxide nanocomposite: From synthesis to antimicrobial and anticancer properties

A green method by Verbascum speciosum was used to synthesize zinc oxide nanoparticles (ZnO NPs). ZnO NPs were coated with silver to synthesize Ag–ZnO nanocomposite (NCs). The physicochemical properties of Ag–ZnO NCs were analyzed by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential. The FTIR indicated the peak of Zn–O vibration and some hydroxyl and carboxyl groups. PXRD analyses confirmed the synthesis of ZnO NPs and Ag–ZnO NCs. Due to the size of the crystallite obtained from PXRD, solid-phase sizes (from FESEM and TEM images), and dynamic sizes from DLS, agglomeration was observed. The Ag–ZnO NCs showed a negative charge surface (?49.3 mV). Ag–ZnO NCs had a high antibacterial activity towards two most important infectious bacteria (i.e., Escherichia coli and Staphylococcus aureus) and anticancer activity against human liver-carcinoma cells (HepG2). Later, it depended on time and concentration of Ag–ZnO NCs. The cytotoxicity properties of Ag–ZnO NCs were also studied against NIH-3T3 as a normal cell, where the results verified the lower cell toxicities of nanocomposite than the HepG2.     

光辅助原位清洁制备Ag/AgCl纳米颗粒

以Ag NO3和反渗透水(RO)中的Cl–为原料,在波长为395 nm的紫外光源(20 W)下原位合成Ag/Ag Cl纳米颗粒。通过透射电子显微镜(TEM)、高分辨率的透射电镜(HRTEM)和动态光散射(DLS)表征了样品的形貌和尺寸分布,用X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见吸收光谱(UV-Vis)和荧光光谱分别对复合材料的晶体结构和元素价态以及光催化性能进行了测试。结果表明:Ag/AgCl复合材料是球形颗粒,平均粒径为100 nm。AgNO_3溶液形成复合纳米颗粒的过程能有效降解罗丹明6G,银离子溶液在光照3 min时罗丹明6G的降解率和猝灭率分别可达96.5%和95%。     

Preparation and characterization of SiO2/polydopamine/Ag nanocomposites with long-term antibacterial activity

Silver nanoparticles (Ag NPs) with diameter of approximately 10 nm were prepared by the reduction of silver nitrate using green synthesis, an eco-friendly approach. The synthesized Ag NPs were homogeneously deposited on silicon dioxide (SiO₂) particles modified with dopamine, leading to the formation of SiO₂/polydopamine (PD)/Ag nanocomposites (NCs) with a core–shell–satellite structure investigated by transmission electron microscopy. The Ag content of SiO₂/PD/Ag NCs determined by inductively coupled plasma optical emission spectrometry was approximately 5.92 wt%. The antibacterial properties of both Ag NPs and SiO₂/PD/Ag NCs against Vibrio natriegens (V. natriegens) and Erythrobacter pelagi sp. nov. (E. pelagi) were investigated by bacterial growth curves and inhibition zone. Compared to Ag NPs, the SiO₂/PD/Ag NCs exhibited superior long-term antibacterial activity, attributed to its controlled release of Ag⁺ ions.     

Ag掺杂Ti/PbO2电极的制备及其在苯酚降解中的应用

使用化学还原和电沉积的方法制备了单质银（Ag）掺杂的Ti/PbO₂电极（Ti/Ag-PbO₂）。在保持镀银液浓度一定的条件下,通过改变镀银的时长制备出三种银含量的钛基体二氧化铅电极（Ti/Ag1-PbO₂、Ti/Ag2-PbO₂、Ti/Ag3-PbO₂）。利用X射线光电子能谱（XPS）和X射线荧光光谱分析（XRF）确定了PbO₂电极中Ag的价态和掺杂量。扫描电子显微镜（SEM）和X射线衍射（XRD）结果表明,Ag掺杂未明显改变电极的表面形态和晶型。根据涂层附着力测试试验发现,掺银PbO₂电极与基底之间有更好的结合力,电极使用寿命提高了约2.5倍。电化学交流阻抗谱（EIS）和循环伏安法（CV）测试结果表明,Ag的掺杂大幅降低了PbO₂电极的电荷转移电阻,提高了电极的电催化活性。利用掺银量2.7%（质量分数）的Ti/PbO₂电极降解100mg/L的苯酚水溶液,相较常规Ti/PbO₂电极,完全降解时间缩短了33.3%,降解能耗下降了34%。     

Effect of Lead Loss and Sheath Structure on Phase Formation and Alignment in (Bi,Pb)2Sr2Ca2Cu3O10+δ/Ag Composite Conductors

The effects of metallic constituent evaporation and sheath structure on grain growth and alignment in silver-sheathed (Bi,Pb)₂Sr₂Ca₂Cu₃O_10+δ (Bi-2223)/Ag composites have been investigated by inductively coupled plasma/atomic emission spectroscopy (ICP/AES), X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Specimens of Bi-2223/Ag composites fabricated by the oxide-powder-in-tube technique were peeled (opened) lengthwise to expose the ceramic powder core, and then heat-treated in 0.075 atm of oxygen for selected temperatures and times. The results were compared with those for as-processed samples with closed silver sheaths treated under identical conditions. ICP/AES analysis indicated that lead was the only metallic element to undergo substantial evaporation during annealing of opened samples. The lead-release process in parallel with the Bi-2223 formation reaction had an activation energy of ∼25 kJ/mol. Lead loss from the opened samples resulted in incomplete conversion to Bi-2223. The combined results show that the silver sheath effectively prevents evaporative lead loss, preserves and promotes densification, and induces texturing of the layered phases.     

Ultrasonic assisted organo-modification of mesoporous SBA-15 with N-trimellitylimido-l-methionine and preparation of the poly(amide–imide)/SBA nanocomposites

Mesoporous SBA-15 materials were functionalized with N-trimellitylimido-l-methionine through ultrasonic irradiation, and the resulting functionalized materials were investigated as reinforcing agent for the preparation of the polymer based nanocomposites (NCs). An optically active and organo-soluble l-methionine containing poly(amide–imide) (PAI) was synthesized by the direct step-growth polymerization reaction of the above chiral diacid and 3,5-diamino-N-(pyridin-3-yl) benzamide in molten tetrabutylammonium bromide as a green solvent. A simple solution blending process was used to efficiently disperse modified-SBA into the chiral PAI to obtain PAI/modified-SBA NCs. The obtained NCs were characterized by Fourier transform-infrared spectroscopy, thermogravimetry analysis (TGA), X-ray diffraction, field emission-scanning electron microscopy, and transmission electron microscopy (TEM) techniques. TGA data indicated an increasing in thermal stability of the NCs when compared to the pure polymer. TEM images show well-ordered hexagonal arrays of mesopores SBA and the average distances between neighboring pores is around 3–5 nm.     

One-Step UV-Induced Synthesis of Polypyrrole/Ag Nanocomposites at the Water/Ionic Liquid Interface

Polpyrrole (PPy)/Ag nanocomposites were successfully synthesized at the interface of water and ionic liquid by one-step UV-induced polymerization. Highly dispersed PPy/Ag nanoparticles were obtained by controlling the experimental conditions. The results of Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy revealed that the UV-induced interface polymerization leaded to the formation of PPy incorporating silver nanoparticles. It was also found that the electrical conductivity of PPy/Ag nanocomposite was about 100 times higher than that of pure PPy.     

Synthesis of ultrathin carbon dots-coated iron oxide nanocubes decorated with silver nanoparticles and their excellent catalytic properties

A facile ultrasonic method has been successfully developed for the fabrication of multifunctional Fe₃O₄@carbon dot/Ag (Fe₃O₄@C-dot/Ag) nanocubes (NCs), and the resulting materials are well characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Vibrating sample magnetometer (VSM) and fluorescence measurements. The Ag nanoparticles (NPs) are uniform and well dispersed on the surface of Fe₃O₄@C-dot, while maintaining the shape and the size of the core-shell Fe₃O₄@C-dot NCs. In addition, its catalytic activities are evaluated by measuring the reduction of p-nitroaniline (p-NA) and crystal violet (CV), and the composite materials exhibit excellent catalytic activity towards reduction of p-NA and CV dye, which is superior to most reported catalysts. The good catalytic performance of Fe₃O₄@C-dot/Ag NCs may be attributed to the specific characteristics of its nanostructure and the synergistic effect on the delivery of electrons between Ag NPs and Fe₃O₄@C-dot NCs. Furthermore, the as-prepared catalysts also show good activity for the reduction of other nitrobenzene analogs. The effect of solvent and reducing agent was also studied on the catalytic activity of Fe₃O₄@C-dot/Ag NCs. Most importantly, the Fe₃O₄@C-dot/Ag catalyst shows excellent recycling stabilities, which can be potentially applied in the fields of catalysis and green chemistry.     

Synthesis of Bio-Based Polyamide/Acid-Functionalized Multiwalled Carbon Nanotube Nanocomposites Using Vanillin

Synthesis of bio-based polyamide/acid-functionalized multiwalled carbon nanotube nanocomposites (PA/FCNT NCs) is reported in this investigation. New aliphatic–aromatic bio-based polyamide (PA) was synthesized through direct polycondensation reaction between bio-based diacid derived from a renewable resource; vanillin and diamine containing ether linkages. To obtain a homogeneous dispersion of multiwalled carbon nanotubes (MWCNTs) in the PA matrix, acid-functionalized MWCNTs (FCNTs) were used and PA nanocomposites with three different FCNT contents (1, 5 and 7?wt%) were prepared. The resulting NCs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA).     

Semi‐aromatic polyimide/Ag nanocomposite derived from vanillin

The development of bioprecursor polyimide/Ag nanocomposites (PI/Ag NCs) is reported in this investigation. Semiaromatic bioprecursor PI was successfully synthesized through direct polycondensation reaction between aromatic diamine containing pyridine ring and aliphatic dianhydride. Aromatic diamine as a monomer was synthesized using a renewable resource, vanillin. The main attractive aspects of this PI are the renewable origin of the diamine, presence of pyridine and high aromatic rings content, as well as aliphatic content on the polymer backbone. The structure of synthesized monomer and PI were proven by FTIR, and nuclear magnetic resonance. The PI/Ag NCs containing 3, 5, and 7 wt % of Ag nanoparticles (Ag NPs) were prepared through solution technique and the resulting NCs were characterized by Fourier transform infrared spectra, wide angle X‐ray diffraction, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). TEM results showed that the Ag NPs were dispersed homogeneously in the PI matrix on nanoscale. TGA results indicated improving in thermal properties of PI/Ag NCs compared to the neat PI due to the interaction between the PI matrix and the Ag NPs. Antibacterial activity of PI/Ag NCs was tested by the disk diffusion method using Escherichia coli as model strain of gram‐negative bacteria. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44001.     

Radiation synthesis, characterisation and antimicrobial application of novel copolymeric silver/poly(2-hydroxyethyl methacrylate/itaconic acid) nanocomposite hydrogels

Silver nanoparticles were fabricated via in situ reduction of silver nitrate embedded in swollen P(HEMA/IA) hydrogel, using gamma radiolysis method. Copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA), previously synthesised by gamma radiation for wound dressing application, were used as a carrier and a stabilising agent, while ethyl alcohol was used as a free radical scavenger. The influence of different P(HEMA/IA) hydrogels and silver salt concentrations on the size and distribution of nanoparticles was investigated. The Ag/P(HEMA/IA) nanocomposites were characterised by high resolution scanning electron microscopy, energy dispersive spectroscopy, wide-angle X-ray diffraction, UV-Vis spectroscopy and swelling measurements. Escherichia coli (Gram-negative bacterium), Staphylococcus aureus (Gram-positive bacterium) and Candida albicans (fungus) were used to prove the antimicrobial properties of Ag/P(HEMA/IA) nanocomposites. The inhibition kinetics of bacteria growth was investigated by measuring the colony-forming unit. The antimicrobial effectiveness of the Ag/P(HEMA/IA) hydrogel nanocomposite was demonstrated even at small silver concentrations. P(HEMA/IA) hydrogels containing nanosilver particles was found suitable to be used as wound dressing.     

A convenient approach to synthesize stable silver nanoparticles and silver/polystyrene nanocomposite particles

In this study, silver nanoparticles were prepared by the reduction of silver nitrate in SDS+ isopentanol/styrene/H₂O reverse microemulsion system using sodium citrate as reducing agent. The Ag/PS nanocomposite particles were prepared by in situ emulsion polymerization of the styrene system containing silver nanoparticles that did not separate from the reaction solution. The polymerization dynamic characteristic was studied, at the same time, silver nanparticles and the encapsulation of composite particles were characterized by Fourier‐transform‐infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X‐ray diffraction (XRD) measurement, UV–vis diffuse reflectance spectroscopy, and X‐ray photoelectron spectroscopy (XPS). The results of TEM and UV–vis absorption spectra showed that well‐dispersed silver nanoparticles have a narrow size distribution. XRD showed that Ag and Ag/PS nanocomposite particles were less than 10 and 20 nm in size, which is similar to those observed by TEM. The results of XPS spectra revealed that the microemulsion system can stabilize the silver nanoparticles from aggregation and provided supporting evidence for the polystyrene encapsulated silver nanoparticle structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Novel chiral poly(amide-imide)/surface modified SiO2 nanocomposites based on N-trimellitylimido-l-methionine: Synthesis and a morphological study

In the present investigation, novel poly(amide-imide) (PAI)/SiO₂ nanocomposites (NCs) containing l-methionine moiety in the main chain were prepared via a simple and fast ultrasonic irradiation process. PAI was synthesized by direct poly condensation reaction of N-trimellitylimido-l-methionine with 4,4′-diamino diphenylether in molten tetra-n-butyl ammonium bromide/triphenyl phosphite as a green condensing agent. Due to the high surface energy and tendency for agglomeration, the surface of SiO₂ NPs was modified with chiral diacid. The obtained NCs were characterized by Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetry analysis, X-ray powder diffraction, field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The FT-IR spectroscopy indicated that the chiral diacid as the coupling agent was attached on the surface of SiO₂ NPs. FE-SEM, and TEM images showed that SiO₂ NPs were dispersed rather homogeneously in the PAI matrix.     

聚乙烯吡咯烷酮/银纳米复合纤维膜的制备及抗菌性

通过液相原位还原法(用乙醇还原硝酸银)获得了合有银纳米粒子的溶胶,从而制得聚乙烯吡咯烷酮(PVP)/银纳米粒子/乙醇纺丝液;再利用静电纺丝技术,得到了含有银纳米粒子的PVP纳米复合纤维膜.利用紫外光谱仪(UV-vis)对溶胶内银纳米粒子进行了表征,运用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对纤维及其内部的纳米粒子的形貌结构和分布进行了表征,并且测试了该样品对大肠埃希菌的抗菌性能.结果表明:利用静电纺丝方法可制取PVP/银纳米粒子复合纤维膜,该膜具有抗菌性.     

银/铂双金属中空纳米颗粒的制备及光学性质研究

通过以Ag纳米颗粒为模板的置换和沉积反应，制备了Ag／Pt双金属复合纳米颗粒、用透射电子显微镜（TEM）对颗粒的形貌、尺寸和结构进行了表征，发现复合颗粒具有中空结构．紫外可见吸收光谱（UV-Vis）研究表明，Ag／Pt双金属中空复合纳米颗粒具有单峰的表面等离子共振吸收特征，随着反应溶液中氯铂酸和硝酸银摩尔比的增加，吸收峰先红移后蓝移．表面增强拉曼光谱实验结果表明，Ag／Pt双金属复合纳米颗粒对吡啶分子具有较好的增强效果．     

Ag-TiO2多孔薄膜及其非紫外光辐照下的超亲水特性

采用溶胶凝胶法，以钛酸丁酯为前驱体、硝酸银络合物为银源、聚乙二醇2000（PEG2000）作为结构导向剂，制备超亲水多孔Ag-TiO₂复合薄膜。用X射线衍射仪、X射线光电子能谱仪、扫描电镜、原子力显微镜表征薄膜晶相结构、化学成分以及表面形貌。根据静态水接触角、动态润湿时间、超亲水长效稳定性综合评价不同Ag含量及PEG2000添加量薄膜的超亲水性能。研究发现，掺杂Ag与PEG2000对薄膜在非紫外光下的超亲水特性具有协同作用，掺杂Ag明显提高薄膜动态润湿速度及可见光响应，表面粗糙多孔结构有利于避光条件下的长效超亲水特性。Ag含量10%、PEG2000掺杂量5%的Ag-TiO₂复合薄膜在自然光条件下已具备优良的超亲水性能；水滴0.2 s内即可在表面完全铺展到0°；避光条件下保存，超亲水时效性可达到30 d以上。在可见光活化下即可强化超亲水性能，具有良好的防雾效果。     

Influence of medium on the nanostructure and properties of poly(4‐aminodiphenylamine)‐silver nanocomposites

Poly(4‐aminodiphenylamine)‐silver nanocomposites were synthesized by an easy one‐step aqueous chemical oxidative polymerization of 4‐aminodiphenylamine (4ADPA) using silver nitrate (AgNO₃) as the oxidant. Two different structure directing surfactants, p‐toluene sulfonic acid (p‐TSA) and cetyl trimethyl ammonium bromide/hydrochloric acid (CTAB/HCl), were independently used for the nanocomposite (NC) preparation. The NCs prepared in p‐TSA and CTAB/HCl medium were designated as P4ADPA/AgNC_(p?TSA) and P4ADPA/AgNC_(CTAB/HCl), respectively. We investigated the morphological variations in the NCs based on the medium. P4ADPA/AgNC_(p?TSA) and P4ADPA/AgNC_(CTAB/HCl) were characterized by field emission scanning electron microscopy, X‐ray diffraction analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis and UV‐visible spectroscopy. Copyright © 2011 Society of Chemical Industry     

A straightforward preparation and characterization of novel poly(vinyl alcohol)/organoclay/silver tricomponent nanocomposite films

In the present investigation, novel poly(vinyl alcohol)/organoclay/silver (PVA/OMMT/Ag) tricomponent nanocomposite (NC) films with different compositions were prepared by solution intercalation method under ultrasonic irradiation process. The NC films were obtained by mixing a colloidal solution consisting of Ag nanoparticles (NPs) (3, 5, 7 and 9 wt%) with a water solution of PVA and OMMT (10 wt%) via solution casting method. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis (TGA) were utilized to characterize the morphology and properties of the PVA/OMMT/Ag NC films. TGA confirmed that the heat stability of the nanocomposite was improved. The enhancement in the thermal properties of the hybrid materials was due to strong hydrogen bonding between OH groups of PVA, free acid functionalized groups of OMMT, and the Ag NPs. SEM and TEM results also showed that the OMMT and Ag NPs were dispersed homogeneously in the PVA matrix on nanoscale.