Key synthesis of magnetic Janus nanoparticles using a modified facile method

Inorganic/organic poly（methylmethacrylate-acrylic acid-divinylbenzene） iron oxide Janus magnetic nanoparticles（P（MMA-AA-DVB）/Fe3O4） with strong magnetic domains and unique surface functionalities were prepared using a solvothermal process.The P（MMA-AA-DVB） nanoparticles were prepared via soapfree emulsion polymerization and used as a precursor for preparing Janus nanoparticles.The morphology and magnetic properties of the magnetic Janus nanoparticles formed were characterized using a laser particle size analyzer,transmission electron microscopy,Fourier transform infrared spectroscopy,vibrating sample magnetometry,and thermogravimetric analysis.The synthesized P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were characterized by a Janus structure and possessed a stable asymmetric morphology after being dually functionalized.The particle size,magnetic content,and magnetic domain of the P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were 200 nm,40%,and 25 emu/g,respectively.The formation mechanism of the Janus nanoparticles was also investigated,and the results revealed that the reduction of Fe3＋ ions and growth of Fe3O4 took place on the surface of the P（MMA-AA-DVB） polymeric precursor particles.The size of the Janus particles could be controlled by narrowing the size distribution of the P（MMA-AA-DVB） precursor nanoparticles.     

Continuous synthesis of iron oxide (Fe3O4) nanoparticles via thermal decomposition

Iron oxide nanoparticles have become of great interest in the medical field for their potential uses in areas such as biomagnetic imaging and hypothermia cancer treatment. Traditionally, particles for these applications are produced through batch-based methodologies. Herein, we demonstrate an alternative continuous flow production method for the synthesis of Fe₃O₄ iron oxide nanoparticles. Advantages of continuous flow over the batch method include consistent formation of uniformly spherical particles, thorough mixing of reactants, and capacity for high-volume particle production. In this study, a continuous flow reaction mechanism was proposed in which stoichiometric control of reactants had the potential to control final particle size. The project was conducted under the supposition that the iron oleate/ligand ratio in the precursor was the greatest size control factor, with a higher ratio resulting in smaller particles. The resulting particles produced by this continuous method were characterized by high-resolution transmission electron microscopy, X-ray diffraction, and magnetometry.     

Synthesis of Fe3O4 nanoparticles by wet milling iron powder in a planetary ball mill

Fe3O4 nanoparticles with sizes ranging from 30 to 80 nm were synthesized by wet milling iron powders in a planetary ball mill. The phase composition and the morphologies of the as-synthesized products were measured by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Nanosized Fe3O4 particles were prepared by wet milling metallic iron powder （-200 mesh, 99%） in a planetary ball mill equipped with stainless steel vials using iron balls under distilled water with a ball-to-powder mass ratio of 50：1 and at a rotation speed of 300 rpm. The use of the iron balls in this method played a key role in Fe3O4 formation. The present technique is simple and the process is easy to carry out.     

ZrO_2纳米微粒的制备、表征及作为MACs添加剂的摩擦学性能

制备了氧化三辛基膦表面修饰的油溶性ZrO2纳米微粒,用透射电镜(TEM)、X-射线衍射仪、红外光谱仪对其进行表征,研究了其作为多烷基环戊烷(MACs)添加剂的摩擦学性能及润滑机理.结果表明:ZrO2纳米微粒粒径大约为7～8 nm,分布比较均匀,无明显团聚,在非极性溶剂中能很好地溶解和稳定分散;作为MACs添加剂,在摩擦过程中,无机ZrO2纳米微粒以沉积膜形式沉积在摩擦副表面,有机修饰剂中的活性P元素在摩擦副表面发生了化学反应,形成了FePO4极压润滑膜,ZrO2沉积膜和FePO4极压润滑膜的协同作用起到了良好的抗磨和抗极压作用.     

纳米碳酸钙作为润滑脂添加剂的摩擦学性能及流变行为研究

使用碳化法制备出三种具有不同粒径的纳米碳酸钙颗粒,利用透射电镜(TEM)和X射线衍射仪(XRD)对其形貌及结构组成进行表征.通过UMT-2摩擦学试验机及RS6000流变仪分别考察了纳米颗粒作为润滑脂添加剂的摩擦学性能及流变学行为,并通过X射线多功能电子能谱仪(XPS)对磨斑表面进行分析.结果表明:所制备的三种纳米颗粒均为方解石结构,可以显著提高基础脂的减摩抗磨性能;添加剂浓度及添加剂尺寸均会影响润滑脂最终的摩擦学性能;在最佳添加浓度和尺寸条件下,能够同时获得最佳的抗磨减摩性能;过高的添加剂浓度会影响润滑脂的结构稳定性,进而影响其摩擦学性能;三种纳米添加剂在磨斑表面形成以碳酸钙为主要成分的润滑膜,纳米颗粒物理性质的差异可能导致其摩擦学性能的差异.     

Shape and size effects of ceria nanoparticles on the impact strength of ceria/epoxy resin composites

Ceria nanoparticles with various shapes (rods, cubes, and plates) and sizes were controllably synthesized and then introduced into epoxy resin. Subsequently, we investigated correlations between the shape and size of ceria nanostructures and the mechanical performance of composites. The samples were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. Compared with commercial ceria filled composites, the composites made with morphology-controlled ceria nano...     

Bi-Pb-Sn-Cd四元合金纳米微粒的制备及其摩擦磨损性能研究

通过直接对Bi-Pb-Sn-Cd四元块状合金进行超声分散制备了相应的四元合金纳米微粒;采用X射线衍射仪和热分析仪分析所制备的纳米微粒结构;采用透射电子显微镜考察了纳米颗粒的形貌及尺寸分布;采用四球摩擦磨损试验机考察了纳米颗粒的摩擦学性能.结果表明,所制备的纳米颗粒为低熔点共晶合金纳米微粒,颗粒平均尺寸在10～20 nm之间,其作为润滑油添加剂表现出良好的摩擦学性能.     

Preparation of Cu–Ni bimetallic nanoparticles surface-capped with dodecanethiol and their tribological properties as lubricant additive

Cu–Ni bimetallic nanoparticles surface-capped with dodecanethiol were prepared via the controlled reduction of nickel nitrate and copper nitrate in the presence of dodecanethiol as ligand and hydrazine hydrate as reductant. The morphology and structure of the Cu–Ni nanoparticles were analyzed by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and thermal gravimetric analysis. Furthermore, the tribological properties of the Cu–Ni nanoparticles as a lubricant additive in liquid paraffin were evaluated with a four-ball machine, and the morphology and elemental composition of the worn surfaces were analyzed by three-dimensional non-contact surface profilometry and X-ray photoelectron spectroscopy, respectively. The results indicated that Cu–Ni nanoparticles prepared at a sufficient dodecanethiol concentration showed almost no signs of aggregation, and exhibited good dispersibility in various apolar solvents. The addition of the Cu–Ni nanoparticles improved the load-carrying capacity as well as friction-reducing and anti-wear abilities of liquid paraffin, attributed to the rolling effect of agglomerated Cu–Ni nanocores released by the Cu–Ni nanoparticles during sliding, and the formation of a boundary lubricating film containing tribochemical reaction products such as iron oxides and iron sulfate.     

In situ synthesis of Ag-SiO_2 Janus particles with epoxy functionality for textile applications

A facile method for the synthesis of silver-silica(Ag-SiO_2) Janus particles with functionalities suitable for textile applications is reported.Silica nanoparticles prepared by the Stober method were functionalized with epoxy,amine,and thiol groups,which were confirmed by Fourier transform infrared analysis.The functionalized silica nanoparticles were used to produce Pickering emulsions,and the exposed surface was used for the attachment of silver nanoparticles(AgNPs) via the low-temperature chemical reduction method.The morphology and structure of the Ag-SiO_2 Janus particles were characterized by scanning electron microscopy,scanning transmission electron microscopy,high-resolution transmission electron microscopy,energy-dispersive X-ray analysis,and UV-vis spectroscopy.Because of their specific functionalities,these Ag-SiO_2 Janus particles are proposed for applications on textile substrates,as they can overcome several drawbacks of direct application of AgNPs on textiles,such as leaching,agglomeration,and instability during storage.     

In situ preparation of hydrophobic CaCO3 nanoparticles in a gas–liquid microdispersion process

This study presents a novel process of in situ surface modification of CaCO₃ nanoparticles using a multiple-orifice dispersion microreactor. CO₂/Ca(OH)₂ precipitation reaction was employed to prepare CaCO₃ nanoparticles with sodium stearate surfactant. Synthesized CaCO₃ products were characterized by thermogravimetric analysis (TGA), infra-red (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer–Emmet–Teller analysis (BET). The effect of various operation parameters on nanoparticles and the dosage of sodium stearate were determined. The results showed that the preparation process could be precisely controlled with efficient mass transfer process. The particles were highly hydrophobic with a contact angle of 117° and monodisperse with an average size of 30 nm. The adsorptions of sodium stearate and calcium ion on solid particles during the in situ surface modification process were investigated.     

In situ synthesis of Ag–SiO2 Janus particles with epoxy functionality for textile applications

A facile method for the synthesis of silver–silica (Ag–SiO₂) Janus particles with functionalities suitable for textile applications is reported. Silica nanoparticles prepared by the Stöber method were functionalized with epoxy, amine, and thiol groups, which were confirmed by Fourier transform infrared analysis. The functionalized silica nanoparticles were used to produce Pickering emulsions, and the exposed surface was used for the attachment of silver nanoparticles (AgNPs) via the low-temperature chemical reduction method. The morphology and structure of the Ag–SiO₂ Janus particles were characterized by scanning electron microscopy, scanning transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray analysis, and UV–vis spectroscopy. Because of their specific functionalities, these Ag–SiO₂ Janus particles are proposed for applications on textile substrates, as they can overcome several drawbacks of direct application of AgNPs on textiles, such as leaching, agglomeration, and instability during storage.     

Controlled growth of silver nanoparticles in a hydrothermal process

A two-step synthesis was used to control the shape of silver nanoparticles prepared via reduction of Ag^＋ ions in aqueous Ag（NH3）2NO3 by poly（N-vinyl-2 First, a few spherical silver nanoparticles,-10 nm in size, were pyrrolidone） （PVP）. Then, in a subsequent hydrothermal treatment, the remaining Ag^＋ ions were reduced by PVP into polyhedral nanoparticles, or larger spherical nanoparticles formed from the small spherical seed silver nanoparticles in the first step. The morphology and size of the resultant particles depend on the hydrothermal temperature, PVP/Ag molar ratio and concentration of Ag^＋ ions. By using UV-visible spectroscopy （UV-vis）, transmission electron microscopy （TEM） and powder X-ray diffraction （XRD）, the possible growth mechanism of the silver nanoparticles was discussed. 2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.     

Modification of silica with PMMA via ultrasonic irradiation and its application for reinforcement of polyacrylates

Polymethyl methacrylate （PMMA） encapsulated silica nanocomposite particles were prepared by ultra- sonically induced in situ polymerization of methyl methacrylate （MMA） on the surface of silica sol. The nanoparticles were characterized by Fourier transform infrared spectroscopy （FFIR）, transmission electron microscopy （TEM）, thermogravimetry （TG）, scanning electron microscopy （SEM）. The results showed that core-shell structure nanocomposite particles with an average size of 36 nm were obtained, and the thickness of polymer encapsulating layer was about 8 nm. The pretreatment of silica sol with tert-butyl hydroperoxide （TBHP） and the addition of ~-methacryloxypropyl trimethoxysilane （MAPTS） significantly enhanced the encapsulation effect. Modified by the polymer layer, the silica particles could be well dispersed in matrices and utilized to improve the mechanical performance of polyacrylates.     

INTERACTION-MEDIATED GROWTH OF CARBON NANOTUBES ON ACICULAR SILICA-COATED α-Fe CATALYST BY CHEMICAL VAPOR DEPOSITION

Multi-walled carbon nanotubes (MWNTs) with 20 nm outer diameter were prepared by chemical vapor deposition of ethylene using ultrafine surface-modified acicular α-Fe catalyst particles.The growth mechanism of MWNTs on the larger catalyst particles are attributed to the interaction between the Fe nanoparticles with the surface-modified silica layer.This interaction-mediated growth mechanism is illustrated by studying the electronic,atomic and crystal properties of surface-modified catalysts and MWNTs products by characterization with X-ray diffraction (XRD),transmission electron microscopy (TEM),high resolution transmission electron microscopy (HRTEM),thermal gravimetric analysis (TGA) and Raman spectra.     

PRODUCTION OF PIGMENT NANOPARTICLES USING A WET STIRRED MILL WITH POLYMERIC MEDIA

Pigment nanoparticles with a size range of 10-100 nm were produced from large agglonmerates via a stirred media mill operating in the wet-batch mode and using polymeric media,The effects of several operating variables such as the surfactant concentration,polystyrene media loading.and media size on the pigment size distribution of the product were studied.The process dynamics was also investigated.Dynamic light scattering and electron microscopy were used as the characerization techniques.The polymeric grinding media are found to be effective for the production of pigment nanoparticles.The experimental results suggest the existence of an optimum media size and surfactant concentration,A population balance model of the process reveals a transition from first-order breakage kinetice for rela-large agglomerates split in a first-order kinetics,with a delay period,for the smaller particles.The model implies that large agglomerates split in a first-order fashion whereas the breakage of individual naoparticles may depend on induced fatigue of the particles.     

Novel self assembly behavior for γ-alumina nanoparticles

In this study, self assembly behavior was induced for γ-alumina nanoparticles by adsorption of dimethyl disulfide. Following this trend, we have developed a chemical process to obtain γ-alumina in the nano scale. Scanning electron microscopy images of the prepared γ-alumina showed big and strong agglomeration of the nanoparticles indicating that these nanoparticles have strong surface forces. Transmission electron microscopy images confirmed that the γ-alumina nanoparticles 3–7 nm in size were converted to uniform spherical shape in the size range of 1–2 mm after shaking with dimethyl disulfide in the presence of n-hexane at room temperature. This phenomenon did not appear in the case of alumina in the micro scale. The surface properties of the prepared γ-alumina in the nano scale were characterized and compared with the γ-alumina in the micro scale by using low temperature nitrogen adsorption–desorption system, indicating that the specific surface area of the prepared γ-alumina nanoparticles is larger than that of the γ-alumina in the micro scale. Furthermore, micro- and meso-pores were observed for the γ-alumina nanoparticles while only mesoporous structure was detected for the γ-alumina in the micro scale. These experimental results suggested that the self assembly behavior of the γ-alumina nanoparticles may be due to the selective adsorption of dimethyl disulfide in the micropores of these nanoparticles to act as bridge linking the nanoparticles.     

NbSe2纳米材料的合成及减摩性能研究

将Se粉和Nb粉按一定的比例混合,然后密封在石英管中或压成片状后密封于石英管中,加热到一定温度,分别获得了NbSe2纳米纤维和NbSe2纳米颗粒.采用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)对所得产物进行了表征,分析了其微观形貌;采用MS-T3000摩擦磨损试验机测定了纳米颗粒作为基础润滑油N40添加剂的摩擦学性能.结果表明,制备的纳米纤维直径100～200nm,纳米颗粒直径40～300nm,二者都具有层状结构和良好的结晶性;NbSe2纳米颗粒作为润滑油添加剂具有明显优于基础润滑油的极压减摩性能;同纳米纤维相比,纳米颗粒的减摩性能较好.     

WSe2纳米结构的合成及减摩性能研究

将W粉和Se粉按一定比例混合,直接密封在石英管中加热或高能球磨、压片,在Ar气氛中加热,得到了不同形貌的WSe2纳米结构.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM、HRTEM)分析了WSe2纳米结构的组成、微观形貌和组织形态;利用UMT-2摩擦试验机考察了WSe2作为HVI500液体基础油添加剂的摩擦磨损性能.研究结果表明:直接密封加热得到的产物为棒状WSe2纳米材料,最小棒直径为6 nm;球磨、压片后加热得到WSe2纳米颗粒,颗粒的平均尺寸在50 nm以下,二者都具有层状结构和良好的结晶性.添加质量分数5%的WSe2纳米材料作为基础油添加剂能够显著降低摩擦系数,减少磨损,增强了材料抗疲劳磨损能力.     

Solvent-less synthesis of zinc oxide nanostructures from Zn(salen) as precursor and their optical properties

ZnO nanoparticles, 10–20 nm in size, were synthesized by heat treatment in air at 500 °C for 5 h., using [N,N′-bis(salicylaldehydo) ethylene diamine]zinc(II), i.e., Zn(salen), as precursor, which was obtained by a solvent-free solid–solid reaction. Heat-treated products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Room temperature photoluminescence spectra of ZnO nanostructures are dominated by green emission attributed to oxygen vacancy related donor–acceptor transition.     

Visible light-driven photocatalysis of W,N co-doped TiO2

W, N co-doped TiO2 nanoparticles were synthesized by a sol-gel method. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FE-SEM）, trans- mission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FT-1R）, X-ray photoelectron spectroscopy （XPS） and diffuse reflectance spectrophotometry （DRS）. The results showed that the co- doped photocatalysts were essentially uniform spherical particles with the smallest particle size of 22.5 nm. Compared to un-doped TiO2, N-TiO2 and P-25, the absorption edge of the W, N co-doped TiO2 shifted to longer wavelength and its photocatalytic activity for degradation of methyl orange （MO） under Xe-lamp （350W） was higher.