核-壳式纳米Al2O3 / PS 复合粒子改性聚苯乙烯的选区激光烧结实验研究

针对纳米粒子易团聚的特点, 利用乳液聚合方法制备纳米Al₂O₃ / PS 复合粒子。用TEM、FTIR 对复合粒子结构进行了表征。结果表明, 所制备的复合粒子具备以纳米氧化铝为核、以聚苯乙烯为壳的核2壳式结构, 而且包覆层厚度大约为10～20 nm。用复合粒子改性选区激光烧结制备聚苯乙烯基纳米复合材料, 通过SEM 和FE2SEM 研究纳米复合材料烧结体的显微结构, 发现纳米粒子较好地分散在聚合物基体中, 且纳米氧化铝与聚合物基体之间的界面相容性和粘结性较好, 烧结体结构较致密。     

纳米Fe3O4/聚苯胺复合粒子的制备及其在交变磁场下的发热性能

用水解沉淀法合成了纳米Fe₃O₄粒子,并在其悬浮液中原位包覆聚苯胺,制备出纳米Fe₃O₄/聚苯胺复合粒子。研究了两种纳米粒子在交变磁场下的发热性能,对它们在定向集热治疗肿瘤中的应用前景进行了评价。纳米Fe₃O₄粒子的粒径为10~30nm,表面包覆聚苯胺后,复合粒子的粒径为30~50nm。纳米Fe₃O₄粒子的比饱和磁化强度为50.05Am2/kg,矫顽力为10.9kA/m;纳米Fe₃O₄/聚苯胺复合粒子的比饱和磁化强度为26.34Am2/kg,矫顽力为0。在10mg/mL的生理盐水悬浮液中,在外加交变磁场作用30min后,纳米Fe₃O₄粒子悬浮液的温度为63.6℃,纳米Fe₃O₄/聚苯胺悬浮液的温度为52.4℃,二者均达到了医学上定向集热治疗肿瘤用热籽的发热要求,是很有应用前景的医用纳米材料。     

松油醇包覆Cu-Ag复合纳米粉的氧化特性

用气-液两相稳定法制备了Cu-Ag复合纳米粉。并用XRD、 HRTEM、 DSC-TG、 红外光谱、 化学分析和氧含量分析等手段研究了粉体的相结构、 表面组成、 形貌、 粒度分布和氧化特性。结果表明, Cu-Ag复合纳米颗粒具有壳核结构, 核为纳米Cu-Ag, 壳为厚度10nm左右的松油醇(C₁₀H₁₈O)分子层和氧化层双层结构, 粉体的粒度分布为20~150nm。在空气中, 220℃包覆在Cu-Ag复合纳米粒子表面的松油醇分子开始氧化, 进而导致Cu-Ag复合纳米粒子在340℃左右迅速氧化, 680℃左右Cu-Ag复合纳米粒子完全氧化。 温度低于220℃时, 气-液两相稳定法制备的Cu-Ag复合纳米粉的抗氧化能力比气相稳定法制备的Cu-Ag复合纳米粉的抗氧化能力好。     

锐钛矿型TiO2 / MnFe2O4 核壳结构复合纳米颗粒的制备及其光催化特性

采用柠檬酸盐前驱体技术, 合成了粒径约为20～70 nm 的尖晶石结构MnFe₂O₄ 纳米颗粒, 用聚乙烯亚胺( PEI) 对MnFe₂O₄ 纳米颗粒进行表面处理后, 以异丙醇钛为前驱物, 采用sol2gel 法在纳米MnFe₂O₄ 表面包覆锐钛矿型TiO₂ 纳米层形成核壳结构。利用透射电子显微镜( TEM) 、X射线衍射仪(XRD) 和振动样品磁强计等测试手段对样品的结构、形貌、粒径以及磁学性能等进行了表征。采用罗丹明B 的光催化降解反应对所制催化剂的活性进行了评价。结果表明, 核壳结构TiO₂ / MnFe₂O₄ 复合纳米颗粒的光催化活性随着壳层厚度的增加而增强,当达到一定厚度以后, 其催化活性不随壳层厚度的增加而改变。复合颗粒中TiO₂ 含量达到30 wt % , 反应时间4 h时, TiO₂ / MnFe₂O₄ 磁性光催化剂对罗丹明B 的光降解率达到100 % , 与纯TiO₂ 纳米粉体的催化活性相当, 且光催化活性稳定, 是一种便于回收、可重复使用的高效光催化剂。     

电沉积Co-Ni-Al2O3复合镀层微观结构及高温性能

在氨基磺酸盐电解液中,利用复合电沉积技术制备得到了Co-Ni合金基中弥散分布Al₂O₃颗粒的金属基复合镀层。通过SEM,AFM以及XRD等分析测试方法,研究了Co-Ni-Al₂O₃复合镀层的表面形貌和微观晶体结构。结果发现:Co-Ni-Al₂O₃的表面形貌和微观晶体结构主要受镀层中钴含量的影响。高钴含量复合镀层具有Hcp结构,其表面形貌比具有Fcc结构的低钴含量镀层的表面更加均匀细致。Al₂O₃颗粒在Co-Ni合金中的共沉积,没有改变合金固溶体的相组成,但却改变了各晶面的优势生长。通过研究复合镀层的硬度、高温耐磨性、高温抗氧化性、热膨胀系数和热导率表明:Co-Ni-Al₂O₃具有较好的高温耐磨性和高温抗氧化能力,并且高钴含量的复合镀层相对于低钴镀层具有较低的热膨胀系数和较高的热导率。     

纳米CaCO3/EPR/PP复合材料性能与结构研究

采用双辊混炼和挤出制样的方法制备了纳米CaCO₃/EPR/PP复合材料。通过PCM、TEM及力学性能测试研究了复合材料的力学性能及EPR和CaCO₃粒子的分散状况。在纳米CaCO₃/EPR/PP复合体系中,纳米CaCO₃粒子的加入,不但使冲击强度显著提高,而且使弯曲弹性模量显著提高。纳米CaCO₃粒子的增韧机理在于纳米CaCO₃粒子的加入使弹性体EPR的分散更加均匀,EPR颗粒的粒径变小,进而与纳米CaCO₃粒子产生协同增韧的作用。     

酞菁镍与Fe3O4纳米粒子的复合机理及复合粒子的结构模型

分析了酞菁镍(NiPc)与Fe₃O₄纳米粒子的复合过程,提出了其复合机理。研究并建立了NiPc-Fe₃O₄纳米复合粒子的结构模型。     

超临界流体干燥法制备TiO2/ Fe2O3 和TiO2/ Fe2O3/ SiO2 复合纳米粒子及光催化性能

以TiCl₄ 、Fe (NO₃ )₃·9H₂O 和Na₂SiO₃19H₂O 为原料, 采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO₂/ Fe₂O₃ 和TiO₂/ Fe₂O₃/ SiO₂ 复合光催化剂。以光催化降解苯酚对所得催化剂的催化活性进行了评价。结果表明, 纳米TiO₂/ Fe₂O₃ 复合粒子与单组分TiO₂ 比较, 复合粒子光催化活性高于单组分的TiO₂, 6h 苯酚降解率高达95.9 %。SiO₂ 的加入可以抑制纳米粒子粒径的长大和晶相的转变, 增强TiO₂ 纳米粒子的热稳定性。复合光催化剂中Fe₂O₃ 最佳掺入量为0.06 %, SiO₂ 最佳掺入量为10 %(摩尔分数) 。并用XRD、TEM 和FTIR 等手段进行了表征。TiO₂ 以锐钛矿型形式存在, SiO₂ 以无定性形式存在。比较了不同制备方法制得的TiO₂/ Fe₂O₃ 复合光催化剂, 得出超临界干燥法制备的光催化剂具有粒径小、比表面积大、分散性好、光催化活性高等特点。采用超临界流体干燥可直接得锐钛型纳米复合光催化剂。     

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。     

回转体表面喷射电沉积Ni-P-ZrO2复合镀层耐腐蚀性能研究

为延长回转体零件的使用寿命,提高其耐腐蚀性能,本文利用喷射电沉积技术在45钢外圆表面制备Ni-P合金镀层和Ni-P-ZrO₂复合镀层,采用扫描电镜、腐蚀失重法和电化学测试分析等测试手段对Ni-P-ZrO₂复合镀层、Ni-P合金镀层和45钢基体在50 g/L NaCl溶液中的表面形貌和耐腐蚀性能进行研究,并探究腐蚀机理。研究表明:Ni-P-ZrO₂镀层相对Ni-P镀层表面致密度更高,缺陷较少;浸泡相同时间, Ni-P-ZrO₂镀层的失重量最小,腐蚀速率最小;电化学测试实验中,Ni-P-ZrO₂复合镀层的腐蚀电流最低(43.2×10^-5 A/cm²),共沉积ZrO₂颗粒后,Ni-P-ZrO₂复合镀层容抗弧半径更大,极化电阻值R_p增大为Ni-P合金的3倍,双层电容值C_d由4.743 8 μF/cm²降低为3.887 2 μF/cm²。在相同条件下腐蚀后,Ni-P-ZrO₂复合镀层的表面较为完好,腐蚀产物较少;Ni-P合金次之,有较多黑色腐蚀产物;45钢表面形貌最差。综上,采用喷射电沉积在回转体表面制备的Ni-P-ZrO₂复合镀层相对Ni-P合金镀层和45钢基体表现出更优良的耐腐蚀性能。     

Structure characterization of Ag-Ga/poly(methyl methacrylate) nanoparticles

The Ag-Ga/poly(methyl methacrylate) nanoparticles were prepared in-situ by emulsion polymerization method under ultrasonic irradiation without any initiators or metal reductant. HRTEM, EDS and XRD experiments were performed to characterize the nanoparticles. The results indicated that the nanocomposite particles possessed core-shell structure with diameters of 80-200 nm, as well as excellent monodispersity. The phenomenon that the polymer forms the shell via layer-by-layer self-assembly was found. XRD proved the existence of Ag0.72Ga0.28 and the probability of new Ag-Ga alloy because of two unknown diffraction peaks.     

Low temperature magnetic hardening in self-assembled FePt/Ag core-shell nanoparticles

The FePt/Ag core-shell nanoparticles with different Ag shell thickness have been fabricated using a seed mediated technique. The core-shell nanoparticles are annealed at temperatures ranging from 350 to 600 °C for 30 min in vacuum. The magnetic measurement demonstrates that the FePt/Ag core-shell nanoparticles show a better chemical ordering tendency with a magnetic hardening temperature of 400–450 °C, which is almost 100 °C lower than that of pure FePt nanoparticles. Negative peaks on the δM curves of the annealed FePt/Ag core-shell nanoparticles demonstrate that the predominant interparticle interactions are dipolar type rather than exchange coupling one. Besides, the FePt/Ag core-shell nanoparticles show both sensitive plasmonic and superparamagnetic properties. The present results indicate that our composite nanoparticles are very promising from the viewpoint of the optoelectronics and biomedical applications.     

Synthesis and characterizations of Ni-Fe@spinel oxide core-shell nanoparticles

Core-shell Ni-Fe@ferrite nanoparticles with an average diameter of 14 nm and shell thickness of 3 nm were synthesized through a redox-transmetalation process. The alloy core and spinel oxide shell were verified by X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy. The hydrophobic oleylamine molecules on the surface were replaced by hydrophilic meso-2,3-Dimercaptosuccinic acid to make the nanoparticles to be water-soluble. X-ray diffraction study of the as-prepared core-shell nanoparticles indicates that they remained face centered cubic alloy core and spinel shell form in air. Magnetic measurements indicate that the core-shell nanoparticles exhibit superparamagnetic and exchange bias characteristics at 300 K and 5 K, respectively.     

Phase transfer identification of core-shell structures in Ag-Au bimetallic nanoparticles

The difference between the transfer of poly(vinylpyrrolidone)-protected Au and Ag nanoparticles from an aqueous solution to toluene was used to develop a simple experimental procedure that can positively identify the formation of bimetallic Ag-Au nanoparticles with the core-shell structure. The method was validated by UV-visible spectroscopy, EDX, and TEM measurements. Using this technique, we have found that core-shell nanoparticles of Ag-Au were formed by the seed-mediated growth method using Ag nanoparticles as the seeds. The reversed order of using Au nanoparticles as the seeds, on the contrary, could only produce a physical mixture of Ag-Au core-shell nanoparticles and isolated Ag nanoparticles.     

Simple and convenient preparation of Au-Pt core-shell nanoparticles on surface via a seed growth method

Au-Pt core-shell nanoparticles were prepared on glass surface by a seed growth method. Gold nanoparticles were used as seeds and ascorbic acid-H₂PtCl₆ solutions as growth solutions to deposit Pt shell on the surface of gold nanoparticles. These core-shell nanoparticles and their growth process were examined by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and field-emission environmental scanning electron microscopy and the results indicated that the deposition speed was fast and nanoparticles with obvious core-shell structure could be obtained after 2 min. Moreover, this seed growth method for preparation of the core-shell nanoparticles is simple and convenient compared with other seed growth methods with NH₄OH as a mild reductant. In addition, electrochemical experiments indicated that these Au-Pt core-shell nanoparticles had similar electrochemical properties to those of the bulk Pt electrode.     

Fe@Ag core-shell nanoparticles with both sensitive plasmonic properties and tunable magnetism

Monodisperse Fe@Ag core-shell nanoparticles with relatively uniform Fe cores and Ag shells have been successfully fabricated by a seed mediated method in a two-step reducing process, and then characterized by electron microscopy techniques (HRTEM, EDX), X-ray diffraction (XRD), UV-vis spectroscopy，and magnetometry. The results demonstrate unique optical and magnetic properties for Fe@Ag core-shell nanoparticles. The surface plasmon resonance of Fe@Ag core-shell nanoparticles is red shifted as compared with that of pure colloidal nano-silver, while the plasmon band of Fe@Ag core-shell nanoparticles with thinner Ag shells is shifted to a longer wavelength. Fe@Ag core-shell nanoparticles have a narrow plasmon band and therefore sensitive plasmonic properties. The magnetism of Fe@Ag nanoparticles can be tuned from superparamagnetic to ferromagnetic by modifying the proportion between Fe and Ag contents. The multifunctional Fe@Ag core-shell nanoparticles have potential in optoelectronic, spintronic, and biomedicine applications.     

核-壳结构纳米磁性复合颗粒的化学制备及应用进展

核-壳结构纳米磁性颗粒作为一种新型材料,具有广泛的应用前景,克服了磁性粒子易于团聚、化学稳定性不高、易受氧化、表面羟基不足等缺点。文中综述了Fe3O4/聚合物和Fe3O4/SiO2两大类核-壳结构的纳米磁性复合颗粒的化学制备方法,包括溶胶-凝胶法、硅烷化反应法、聚合法、自组装法、超声波法、高温合成法、凝结法、超临界流体...     

具有癌症诊疗潜力的多功能核壳纳米粒

采用乳化-溶剂挥发法制备了同时携载Mn3O4纳米粒和CuS白蛋白纳米粒的诊疗一体化多功能核壳纳米粒,可用于磁共振造影成像手段指引下的肿瘤光热消融,实现癌症的高效诊治.首先用高温热解法制备出粒径均一、分散性较好的Mn3O4纳米粒,并通过蛋白模板法制备CuS白蛋白纳米粒,之后采用可降解性聚乳酸-羟基乙酸共聚物(PLGA)作为载体,通过超声乳化法制备同时携载Mn3O4和CuS纳米粒的核壳纳米粒(Mn3O4/PLGA@CuS),并进行理化性质表征及诊疗一体化性能评价.结果表明:紫外-可见-近红外分光光度计测定结果显示该纳米粒被成功制备,其在近红外区具有较强吸收;核壳纳米粒的平均粒径为160 nm,粒径分布较为均匀;体外磁共振造影成像结果显示随着纳米粒中Mn离子浓度的升高,其造影增强效果也明显提升,显示其具有Mn离子浓度依赖的磁共振成像效果,纵向弛豫率为1.351 mM-1·s-1;在785及980 nm激光辐照下,该核壳纳米粒均显示出良好的光热升温效果.成功制备了具有良好的磁共振造影成像性能和显著的光热升温效应的核壳纳米粒,有望应用于肿瘤的诊疗一体化.     

Facile synthesis of near-monodisperse Ag@Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 ± 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H(2) from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.     

Iron nanoparticles produced by precipitation phenomena in solid state

This paper shows the possibility of nanoparticle preparation by precipitation in solid state and isolation by electrochemical dissolution of matrix. Two variants of nanoparticles were prepared by heat treatment of Cu-Fe supersaturated solid solution. The obtained nanoparticles with mean diameters of about 10 nm and 21 nm were examined by transmission electron microscopy and XRD analysis as core-shell nanoparticles, consisting of an α-Fe core and a 2-line ferrihydrite shell.