Synthesizing tertiary silver/silica/kaolinite nanocomposite using photo-reduction method: Characterization of morphology and electromagnetic properties

Silver was loaded on silica/kaolinite by photo-reduction technique. The present study investigated the effects of the UV irradiation on different characteristics of the particles employing X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), UV–vis spectrophotometer (UVS), Brunauer–Emmett–Teller specific surface area method (BETM), zeta potential measurement (ZPM), thermal gravimetric analysis (TGA), scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDX) and electromagnetic transition instrument (ETI). XRD, FTIR as well as UV absorption methods evidenced that synthesizing procedure was successful under UV irradiation. TGA results demonstrated that the Ag nanoparticles (AgNPs) generated on the silica/kaolinite surface can decrease thermal stability of particles due to proton delocalization of hydroxyl groups and Hofmann–Klemen effect. EDX results showed the presence of chemical elements namely Fe, Al, Si, Mg, K, Ti, Ag, Ca and Fe on the surface of tertiary nanocomposite. The synthesized silver/silica/kaolinite particles were found to have a higher electromagnetic absorption activity compared with silica/kaolinite. As a result, they can be used in polymer-based composites for preparing high performance electromagnetic interference shielding materials.     

Synthesis of silver/poly (diallyldimethylammonium chloride) hybride nanocomposite

This paper presents a method for the preparation of silver nano-particles in poly (diallyldimethylammonium chloride) (PDDA) using N,N-dimethylformamide (DMF) as a medium has been performed successfully. A golden solution in its UV–vis absorption spectrum showed surface plasmon resonance absorption bands between 410 and 425 nm in solutions and at about 461 nm in a transparent film. The Ag/PDDA nano-composite was characterized by X-ray diffraction (XRD) measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform-infrared spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA). XRD showed the fcc crystal structure of the bulk Ag with particles of <22 nm in size similar to that is observed by TEM and PDDA is crucial to the formation of such silver nano-composite. SEM indicated uniform distribution of particles in the film. TGA confirmed enhanced thermal stability of the polymer.     

Citric acid/ZrO2 nanocomposite inducing thermal barrier and self-cleaning properties on protein fibers

The present research carried out to stabilize nano-ZrO₂ on the wool fabric using citric acid (CA) as a crosslinking agent and sodium hypophosphite (SHP) as a catalyst under UV irradiation. The influence of the amount of nano-ZrO₂ on the performance of wool fiber was investigated by the use of Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscope (EDX) and reflectance spectrophotometer (RS). The possible interactions between nano-ZrO₂ particles, cross-linking agent and wool free radicals were elucidated by the FTIR spectroscopy. Results indicated that the stabilized nano-ZrO₂ enhances the thermal stability of wool. Photo-catalytic activities of the coated wool were evaluated through degradation of methylene blue (MB) under UV irradiation.     

Production and characterization of nanosized Cu/O/SiC composite particles in a thermal r.f. plasma reactor

An inductively coupled thermal plasma process was used to produce nanosized Cu/SiC composite particles. The powders were characterized by means of chemical analysis, energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), specific surface measurements (BET), X-ray powder diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). X-ray absorption fine structure analysis (EXAFS) was performed to determine the near range order structure of the nanosized particles.     

Synthesis of silver and sulphur codoped TiO<Subscript>2</Subscript> nanoparticles for photocatalytic degradation of methylene blue

In the present work, silver and sulphur codoped TiO₂ (Ag–S/TiO₂) photocatalysts were effectively prepared by sol–gel technique. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance UV–Vis spectroscopy (UV-DRS) and photoluminescence (PL). The XRD patterns consisted of anatase crystalline phases and the particle size and shape of the prepared samples were observed by SEM and HR-TEM. The presence of doping ions was confirmed by EDX analysis, the decreased band-gap energy of Ag–S codoped TiO₂ nanoparticles was investigated by UV-DRS. The decreased in the intensity of Ag–S codoped TiO₂ was absorbed due to the lower separation of electron–hole pairs were confirmed by PL spectrum. The Ag–S codoped TiO₂ showed higher photocatalytic activity than pure and single-doped TiO₂ in the photodegradation of methylene blue (MB) aqueous solution under visible light irradiation. The given work was a good model to associate the considering of the synergistic effect of metal and non-metal codoped TiO₂ in the photocatalysis and photo electrochemistry.     

Preparation of silica hollow fibers by surface-initiated atom transfer radical polymerization from electrospun fiber templates

Silica hollow fibers were produced by surface-initiated atom transfer radical polymerization (ATRP) from poly(methyl methacrylate-co-vinylbenzyl chloride) (P(MMA-co-VBC)) electrospun fibers combined with sol-gel process and subsequent calcination. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to characterize the intermediate products and the silica hollow fibers. The resulting silica hollow fibers are of high purity with amorphous morphology. The thickness of the hollow fibers is approximately 0.25 µm.     

Ag掺杂APS改性的TiO2颗粒的制备及其光催化降解作用

为提高Ag/TiO2纳米颗粒的光催化降解作用,采用聚合凝胶工艺路线,以钛酸四丁酯为前驱体,硝酸银为银源,通过向反应体系引入鳌合剂醋酸、表面改性剂γ-氨丙基三乙氧基硅烷(APS)以及还原剂甲醛等添加剂,制备出TiO2粉体及Ag/TiO2纳米复合粉体。利用FT-IR、XRD、TG-DTA、TEM和UV-Vis-NIR等手段对样品进行表征。结果表明,经γ-氨丙基三乙氧基硅烷改性的TiO2颗粒掺Ag后分散性得到改善,粒径约1 nm的Ag颗粒较均匀地分布在10～15 nm TiO2颗粒上;可见光的利用和锐钛矿热稳定性都得到提高;Ag/TiO2纳米颗粒在光照下对甲基橙具有良好的光催化降解效果。     

SiO2 / Ni 核壳结构纳米粒子的制备及其磁性能

以硅酸钠为主要原料, 通过液相沉淀法在纳米镍粉表面包覆了一层SiO₂ 。应用XRD、FTIR、TEM、TGA、DSC 和VSM 对复合粉体的结构、形貌和磁性能进行了研究。结果表明, SiO₂ 以非晶态的形式包覆在纳米镍粒子表面, 形成了核壳结构, 降低了纳米粉体的团聚现象。TGA 和DSC 结果表明, SiO₂ 的包覆提高了纳米粉体的抗氧化性。磁性分析结果表明, 粉体包覆前由于表面氧化层(NiO) 的存在, 粉体的磁滞回线偏移; 包覆后的粉体由于SiO₂的存在, 饱和磁化强度降低, 矫顽力升高。      

Synthesis of Nanocrystalline Barium Ferrite in Ethanol/Water Media

Nanocrystalline particles of barium ferrite magnetic material have been prepared by co-precipitation route using aqueous and non-aqueous solutions of iron and barium chlorides with a Fe/Ba molar ratio of 11 and subsequent drying-annealing treatment.Water and ethanol/water mixture with volume ratio of 3:1 were used as solvents in the process.Coprecipitated powders were annealed at various temperatures for 1 h.FTIR(Fourier transform infrared spectroscopy),XRD(X-ray diffraction),DTA/TGA(differential thermal an...     

Characterization of SiO2/Ag composite particles synthesized by in situ reduction and its application in electrically conductive adhesives

In the study, SiO₂/Ag composite particles with silver coating onto the surface of silica have been successfully prepared via a novel and facile approach (Oxidation–Reduction Method). In this approach, the SiO₂ particles were first modified with 3-ammoniatriethoxysilane (APTES) and glyoxalic acid (GA) through two-step reaction, the aldehyde group (CHO) were anchored onto the surfaces of silica spheres via electrostatic attraction, these [Ag(TEA)₂]⁺ ions in the solution were then reduced by the CHO and coated onto the surface of silica to obtain SiO₂/Ag composite particles. The effects of the reaction conditions on silver content and synthetic mechanism had also been discussed. The structure, morphology and optical properties of the SiO₂/Ag composite particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis spectroscopy. The results showed the surface of SiO₂ was surrounded by pure silver nanoparticles, and the silver nanoparticles had face-centered-cubic structure, the SiO₂/Ag composite particles with core–shell morphology and special optical properties. And the small content SiO₂/Ag composite particles applied in electrically conductive adhesives (ECAs) improved the electrical bulk resistivity and tensile shear strength.     

Modifying Fe3O4-functionalized nanoparticles with N-halamine and their magnetic/antibacterial properties

Magnetic/antibacterial bifunctional nanoparticles were fabricated through the immobilization of antibacterial N-halamine on silica-coated Fe(3)O(4)-decorated poly(styrene-co-acrylate acid) (PSA) nanoparticles. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA). The N-halamine was developed from the precursor 5,5-dimethylhydantoin (DMH) by chlorination treatment, and experimental results showed that the loading amount of DMH on the silica-coated Fe(3)O(4)-decorated poly(styrene-co-acrylate acid) nanoparticles was adjustable. The as-synthesized nanoparticles exhibited superparamagnetic behavior and had a saturation magnetization of 18.93 emu g(-1). Antibacterial tests showed that the resultant nanoparticles displayed enhanced antibacterial activity against both Gram-positive and Gram-negative bacteria compared with their bulk counterparts.     

Grafting electrosprayed silica microspheres on cellulosic textile via cyanuric chloride reactive groups

A novel method of covalently grafting solid or hollow microcapsules on cellulosic textiles was developed by surface functionalisation of capsules with reactive triazine moieties. Demonstrative silica microspheres, with 454 nm average particle size, were developed by electrospraying silica sol prepared via sol–gel process. The chemical–physical properties of submicron particles were characterised by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA) and scanning (SEM) and transmission electron microscopy (TEM). As a potential process towards functional textiles, the micro/nanosphere surface was modified with chlorotriazine ligands in a two-step procedure to react with the hydroxyl groups in cellulose under mild conditions. The first amine functionalisation was demonstrated by evaluation with FTIR and silicon-29 nuclear magnetic resonance (²⁹Si-NMR), as well as using TGA. Subsequent chemical functionalisation of an amine–silica surface with triazine moieties was analysed by FTIR, proton solid-state NMR spectroscopy (¹H-NMR) and TEM coupled to an X-ray detector. Finally, the covalent bonding of silica nanoparticles to cellulose was performed under simulated dying conditions and it was evaluated by SEM in combination to energy dispersive X-ray spectroscopy.     

Synthesis of Ag-AgBr/Al-MCM-41 nanocomposite and its application in photocatalytic oxidative desulfurization of dibenzothiophene

A series of Ag-AgBr/Al-MCM-41 nanocomposites were synthesized by dispersion of Ag-AgBr on mesoporous silica Al-MCM-41 obtained from natural bentonite. The synthesized Ag-AgBr/Al-MCM-41 composites with Ag nanoparticles growing on the surface of Al-MCM-41 were used for photocatalytic oxidative desulfurization of dibenzothiophene. The physical properties of Ag-AgBr/Al-MCM-41 were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS), photoluminescence (PL) emission spectra, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity results showed that in the presence of 40% Ag-AgBr/Al-MCM-41 photocatalyst the oxidative desulfurization of dibenzothiophene reached the maximum efficiency at 99.22% and the photocatalytic activity still keeps high level after four cycles.     

Synthesis and characterization of silver/thiophene nanocomposites by UV-irradiation method

Silver/thiophene (Ag/Th) nanocomposites have been prepared by UV-irradiation method. The resulting products were characterized by Elemental Analysis (EA), X-ray Photoelectron Spectroscopy (XPS), optical absorption spectroscopy, Fourier Transform Infrared (FT-IR), Thermal Gravimetric Analysis (TGA), X-ray Diffraction (XRD), transmission electron microscopy (TEM) and Scanning Electron Microscope (SEM). We prepared Ag/Th nanocomposites successfully for the first time without any reducing or binding agent. XRD patterns are consistent with that of silver and thiophene molecules are present in the final products. A SEM image shows the uniform particles distribution. The particles are spherical in nature and seem to be nanosized, typically in the range of < 100 nm. Finally, we observed a strong interaction between the Ag⁺ ion and sulfur atom of thiophene ring. This work provides a simple route for the synthesis of Ag/Th nanocomposites.     

Synthesis of polyaniline/Ag composite nanospheres through UV rays irradiation method

In this paper, a novel morphology of polyaniline (PANI)/Ag composite nanospheres was obtained through UV rays irradiation method. The structure and morphology of the product were characterized by Fourier transform infrared (FT-IR) spectrum, X-ray diffraction (XRD) pattern, Scanning electron micrograph (SEM) and Transmission electron microscopy (TEM) images, energy-dispersive X-ray (EDAX) analysis, and electron diffraction (ED), respectively. The results showed that the diameters of the PANI nanospheres and the Ag nanofilaments were 10–60 nm and 2–5 nm, respectively. UV rays played an important role for forming PANI nanospheres underpinned by Ag nanofilaments. A potential formation mechanism of PANI nanospheres underpinned by Ag nanofilaments was investigated.     

热处理对二氧化钛表面二氧化硅包膜的影响

通过单流匀速滴定法在二氧化钛颗粒表面均匀包覆一层二氧化硅,系统地研究热处理温度对这层硅包覆层的形貌和相组成的影响;采用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、透射电子显微镜(TEM)和傅立叶红外光谱仪(FTIR)等手段对包硅二氧化钛颗粒进行表征。结果表明:150℃热处理形成连续致密的硅二氧化硅覆层;500℃热处理3 h后形成岛状二氧化硅膜;700℃热处理后形成不连续的硅二氧化硅覆层,并有脱落的倾向;当温度升到1 000℃时,硅二氧化硅覆层会脱落,二氧化钛的粒径增大,大约在1 000℃,二氧化硅包覆层结晶化。     

壳核型聚苯胺/钛酸钡复合电流变材料的制备及表征

采用溶液聚合的方法,在经过硅烷偶联剂表面修饰的钛酸钡微粉表面原位聚合聚苯胺,得到聚苯胺/钛酸钡壳核结构(BaTiO3/PAn)的有机-无机复合粒子.借助SEM、XRD、FT-IR、DSC-TG等分析手段研究了复合粒子的形貌、结构及热性能.利用改装后的旋转粘度计分别对钛酸钡和聚苯胺/钛酸钡复合颗粒的电流变性能进行研究.结果表明利用硅烷偶联剂成功地在钛酸钡粒子表面接枝合成聚苯胺,聚苯胺/钛酸钡复合颗粒电流变液的电流变性能明显比纯钛酸钡的电流变性能有所提高.     

Synthesis and ferrimagnetic properties of novel Sm-substituted LiNi ferrite–polyaniline nanocomposite

Polyaniline (PANI)–LiNi_0.5Sm_0.08Fe_1.92O₄ nanocomposite was synthesized by an in situ polymerization of aniline in the presence of LiNi_0.5Sm_0.08Fe_1.92O₄ ferrite. The products were characterized by powder X-ray diffractometer (XRD), Fourier transform infrared (FTIR) and UV–visible absorption spectrometer, thermogravimetric analyser (TGA), atomic force microscope (AFM) and vibrating sample magnetometer (VSM). The results of XRD, FTIR and UV–visible spectra confirmed the formation of PANI–LiNi_0.5Sm_0.08Fe_1.92O₄ composite. AFM study showed that ferrite particles had an effect on the morphology of the composite. TGA revealed that the incorporation of ferrite improved the thermal stability of PANI. The nanocomposite under applied magnetic field exhibited the hysteresis loops of ferrimagnetic nature at room temperature. The bonding interaction between ferrite and PANI in the nanocomposite had been studied.     

Preparation and characterization of conducting polyaniline/silica nanosheet composites

A series of polyaniline/silica nanosheet composites (PANI/SNS) with different contents of the silica nanosheets derived from vermiculite via acid-leaching were prepared via the in situ chemical oxidation polymerization. The PANI/SNS composites were characterized with Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and electrical conductivity measurement. It is interesting that the electrical conductivities of the PANI/SNS composites increased with the increasing of the contents of the silica nanosheets added because of the moisture absorption. It was confirmed by the TGA analysis.     

Effect of silica particles modified by in-situ and ex-situ methods on the reinforcement of silicone rubber

In-situ and ex-situ methods were applied to modify silica particles in order to investigate their effects on the reinforcement of silicone rubber. Surface area and pore analyzer, laser particle size analyzer, Fourier-transform infrared spectroscopy (FTIR), contact-angle instrument, and transmission electron microscope (TEM) were utilized to investigate the structure and properties of the modified silica particles. Dynamic mechanical thermal analyzer (DMTA) was employed to characterize the vulcanizing behavior and mechanical properties of the composites. Thermogravimetric analysis (TGA) was performed to test the thermal stability of the composites. FTIR and contact angle analysis indicated that silica particles were successfully modified by these two methods. The BET surface area and TEM results reflected that in-situ modification was more beneficial to preparing silica particles with irregular shape and higher BET surface area in comparison with ex-situ modification. The DMTA and TGA data revealed that compared with ex-situ modification, the in-situ modification produced positive influence on the reinforcement of silicone rubber.