中空介孔二氧化硅微球的制备及研究进展

中空介孔二氧化硅微球具有较大的中空空腔、可控外层介孔结构、大比表面积、良好的生物相容性等特性,因而被广泛应用于药物储存与释放、纳米反应器、催化、吸附等领域。对中空介孔二氧化硅微球的制备方法进行介绍,综述和评价了模板法、选择性刻蚀法、喷雾干燥法等三类制备方法的研究进展及其优缺点,并对其应用前景进行了展望。     

ZnS包覆 SiO2核壳和空腔结构纳米球制备研究

ZnS包覆SiO2三维核壳结构或空腔结构纳米球可用于光子晶体的组装.本实验采用层层自组装法,利用二氧化硅模板表面的静电作用吸附纳米晶粒子,生成纳米晶包覆层,制备核壳结构的SiO2@ZnS和SiO2@ZnS：Mn^2＋纳米球.控制氢氟酸对二氧化硅的蚀刻程度,制备了空腔型硫化锌纳米球.采用XRD、UV、PL、TEM、SEM、AFM等测试手段对核壳结构和空腔型硫化锌纳米球进行了表征.结果表明ZnS纳米晶包覆SiO2后,在其表面形成了包裹紧密、形貌规整、粒径均一的ZnS壳层;经5%氢氟酸蚀刻得到的空腔纳米球结构完好、厚度均匀.     

中空结构纳米TiO2微球的可控制备

纳米TiO_2作为一种氧化还原能力强、化学性质稳定、来源广泛和环境友好的多功能材料,被认为是非常有前景的半导体光催化材料之一。在各种形貌的纳米TiO_2中,中空结构TiO_2微球因具有密度低、比表面积大、渗透性好和稳定性高的特点而受到越来越多研究者的青睐。寻求工艺简单、重复性好和产物形貌可控的中空纳米TiO_2微球的制备方法显得尤为重要。中空纳米TiO_2微球的制备方法根据制备原理可分为溶胶-凝胶法、水热法、溶剂热法、喷雾干燥法和层层自组装法等;根据制备过程中是否加入模板剂又可分为硬模板法、软模板法和无模板法。本文针对硬模板法、软模板法和无模板法进行了综述。其中,硬模板是最早应用于中空TiO_2微球制备的方法,最终所得中空TiO_2的形貌、空腔大小和表面所带电荷与所用模板剂种类密切相关。目前常用的模板剂有三大类,包括聚合物、碳球和无机氧化物。而在制备模板剂过程中需要消耗大量的时间和有机溶剂,造成成本升高和环境污染。软模板法是目前最高效的一种制备方法,其制备机理与硬模板法较为相似,主要区别在于模板剂的选择上,前者的模板剂大多为刚性较强的无机粒子,而软模板剂通常为乳液液滴、超分子胶束、聚合物聚集体/囊泡等强度较低的气体或者液体。相比于硬模板法其最明显的优势在于后期对于模板剂的去除较为容易,不需要高温处理,多次洗涤即可除去,因此具有效率高、工艺简单等优势。无模板法是一种最具应用潜力的中空TiO_2微球制备方法。此法大多为一步反应,因此其可控性较差,尚未实现大范围应用与生产。但是,该法具有制备步骤少、成本低和产率高等优势,在后期的批量生产和规模化制备中空TiO_2微球方面具有潜在的优势。目前,对于中空纳米TiO_2微球的研究除了有效且成熟的制备工艺外,其高效的光催化性能也是研究者追求的目标。笔者认为通过以下三方面可以进一步提高中空纳米TiO_2的光催化性能:其一,多种半导体材料的复合可拓宽其在可见光下的响应区域;其二,非金属阴离子(氮、碳)或金属(铁、铜)离子参杂等可提高光诱导二氧化钛电子空穴对的分离效率;其三,金属氧化物的表面修饰或双原位聚合改性等多种手段共同作用可降低电子-空穴对的重组。延长光生载流子的寿命、提高光催化活性将成为今后中空TiO_2微球研究的重点。     

二氧化锡纳米中空球制备研究进展

综述了近年来纳米二氧化锡中空球的制备方法,包括硬模板法、软模板法、溶胶-凝胶法、水热法、奥斯特瓦尔德熟化法、一步烧结法、超声喷雾热解法等。对纳米二氧化锡中空球材料的发展前景和制备方法进行了展望。     

“核-壳-冠”聚合物胶束模板合成无机中空纳米材料的研究进展

无机中空纳米材料由于其低密度、高表面/体积比、低热膨胀系数等特点,近年来在催化、锂电池电极材料、药物输送等诸多领域显示出了突出的应用潜力。目前,此类材料的制备方法中,应用最为广泛的是模板法。早期的模板法多采用硬模板法,硬模板一般包括金属晶体、二氧化硅纳米球和PS乳胶纳米球等,但该方法存在因合成工艺步骤复杂导致的产物产率较低,以及模板去除时外壳结构脆弱等缺点。为克服上述缺点,后续的研究主要转向软模板法,常见的软模板包括乳液液滴、表面活性剂胶束和嵌段共聚物胶束等。然而,近年来的研究发现,当采用乳液液滴或者表面活性剂胶束作为软模板来制备无机中空纳米材料时,由于上述软模板的可变形性,会导致所制备的无机中空纳米材料的形态和分散性较差。基于这些发现,后续的研究又相继转向利用两亲性分子来合成无机中空纳米材料。两亲性分子可自组装为有序的球形等形状的胶束,这些胶束主要由单分子、AB二嵌段、ABA三嵌段共聚物等形成"核-冠(Core-corona)"结构,嵌段共聚物胶束可以为中空纳米结构提供相对更刚性的空心支架,从而实现更好的尺寸和形状控制。但是,实验发现,采用此类胶束的冠(Corona)作为外壳形成的模板时,胶束的冠区域会因为吸收无机壳层材料的前驱体而变得不稳定,易导致严重的团聚现象。因此,目前最新的一些研究成果主要通过新开发三组分ABC三嵌段共聚物来克服上述软模板的缺陷,ABC三嵌段共聚物胶束可以为无机纳米组装体提供比AB二嵌段和ABA三嵌段共聚物更多样的形态和功能特征,而且无机材料的前驱体被刻意选择性地吸附到胶束的壳层(Shell)区域,保证了胶束的冠区域免于被无机前驱体沉积,从而极大地提高了整个胶束的稳定性,避免了产物发生严重的团聚。目前,采用PS-PVP-PEO、PS-PVMP-PEO、PS-b-PAA-b-PEO等不同形式的ABC三嵌段共聚物形成的"核-壳-冠(Core-shell-corona)"聚合物胶束,已成功制备了中空氧化硅纳米球、金属氧化物中空纳米球、中空氧化钛纳米球、含金属氧化物在其空腔的中空介孔二氧化硅纳米结构等。在这些无机中空结构的制备过程中,聚合物胶束的核区域主要作为中空空核形成的模板;壳区域主要作为无机前驱体溶胶-凝胶反应的反应区;冠区域起到稳定胶束的作用。本文归纳了应用"核-壳-冠"聚合物胶束制备无机中空纳米材料的研究进展,分别对聚合物胶束模板的发展情况、不同结构的无机中空纳米材料的制备方法和机理等进行了介绍,并着重介绍了无机中空纳米材料在锂电池电极材料、催化以及药物输送等领域的应用情况,以期为发展更优异的无机中空纳米材料制备方法和进一步拓展该类材料的应用提供参考。     

核-壳式聚苯乙烯/二氧化硅复合微球及空腔硅球的制备

利用层层自组装的方法制备了粒径和组成可裁剪、具有核-壳式结构的单分散聚苯乙烯(PS)/二氧化硅(SiO₂)复合微球.对复合微球进行热处理除去有机物中心,制备出壁厚可剪裁的空腔硅球.透射电镜(TEM)照片显示二氧化硅纳米颗粒在中心外生成均匀壳层,而煅烧后则可得到轮廓分明的球形空腔;热重分析(TG)说明复合球体的硅含量随着所组装的纳米二氧化硅的粒径的增加而增加;比较PS、SiO₂、复合球体及热处理后的粉体的红外光谱,可分别验证二氧化硅的成功组装和热处理过程中作为中心的PS的完全去除.在吸附相同层的前提下,随着所选用的二氧化硅纳米粒子(10um,20um,40um)的粒径的增大,复合微球的粒径增大,空腔球体的壁厚增加.     

中空SiO2微球的制备及其在缓/控释应用中的新进展

中空二氧化硅(SiO₂)微球具有特殊的内部空腔、吸附渗透性好、物质传递可控等优异性能, 可储存负载并缓慢释放药物、香精、染料、菌素等客体分子, 因此在药物缓释、医学成像、环境保护以及化妆品等领域有着广阔的应用前景。根据国内外研究进展, 本文归纳对比了中空SiO₂微球几种制备方法之间的优劣差异, 着重阐述了其作为缓控释载体表现出的持久性和高效性, 以及功能化的有机/无机杂化微球在响应性控释方面的优越性。并对中空SiO₂微球作为新型缓控释载体的发展前景进行了展望。     

氨基酸辅助制备二氧化硅纳米球及其应用

总结了氨基酸辅助法制备二氧化硅纳米球以及通过种子再生长过程进行尺寸控制的制备方法,对其形成机理进行了探究,介绍了这种二氧化硅纳米球在生物医药、阵列模板、功能薄膜和高分子接枝杂化合成方面的应用,并展望了这种单分散性二氧化硅的应用前景.     

自组装法制备中空二氧化硅纳米粒子减反射薄膜

以正硅酸乙酯(TEOS)为壳层材料, 聚丙烯酸(PAA)为核材料, 以传统的Stöber水解法为基础制备得到结构规整的中空二氧化硅纳米粒子, 并采用自组装法制备单层减反射薄膜和宽波段双层减反射薄膜。主要研究中空二氧化硅纳米粒子的结构调控方法; 自组装次数和中空二氧化硅纳米粒子分散液的pH值对减反射薄膜透光率的影响规律, 以及具有渐变折射率的双层减反射薄膜的制备。研究结果表明: 通过调节PAA和TEOS的用量可精确调控中空二氧化硅纳米粒子的粒径和空腔体积分率, 进而可精确调控减反射薄膜的厚度和折射率; 通过酸洗工艺, 将自组装次数由10次减少为2次, 简化了涂膜的工艺条件, 在最佳工艺条件下所制备的单层减反射薄膜在350~800 nm波长范围内可显著提高玻璃的透光率, 在最佳波长(λ=520 nm)处将玻璃的透光率由91.6%提高至98.1%; 双层减反射薄膜可在更宽的波段范围内提高基材的透光率, 在400~1500 nm波长范围内将玻璃的透光率提高了5%以上。     

中空介孔二氧化硅球的制备及应用现状

中空介孔二氧化硅球具有低密度,高比表面积,良好的稳定性,在溶剂中良好的分散性以及好的生物兼容性,在化学、生物技术、医学等领域具有广泛的应用前景。综述了中空介孔二氧化硅球的制备方法和应用现状,并对应用前景进行了展望。     

聚合物空心纳米球的制备和表征的研究进展

综述了近年来国内外聚合物空心纳米球的研究现状,重点阐述了聚合物空心纳米球的制备方法,包括自组装法、微乳液聚合法和模板法等,比较了各种制备方法的制备原理和优缺点,介绍了聚合物空心纳米球的表征手段,最后展望了聚合物空心纳米球的发展前景.     

Facile synthesis of hollow carbon nanospheres from hollow chitosan nanospheres

Hollow carbon nanospheres (HCNS) with large surface area were synthesized from hollow chitosan nanospheres by one-step pyrolysis with a relatively low temperature (550 degrees C). The resulted HCNS is fully carbonized and partially graphitized under the experiment conditions. It is an important and facile method to prepare the uniform, shape- and size-controlled carbon nanomaterials by carbonization of the natural polysaccharide compounds and their derivatives. The as-prepared HCNS has a narrow size distribution in hollow carbon nanospheres (about 53 nm). The structure and size of HCNS are reproducible and could be tunable by changing the preparation conditions. The characterizations to estimate the composition, decompose properties, crystalline form, structure and surface property of the HCNS were investigated using FT-IR spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction measurement (XRD), transmission electron microscopy (TEM) analysis, and the N2 adsorption-desorption isothermal process. The present preparation method makes it feasible to synthesize carbon nanospheres in abundance in the lab, and the synthesized HCNS could be a promising support for metal catalysts, an ideal matrix connecting with DNA or other bioactive substances.     

Solution‐Processable Photonic Inks of Mie‐Resonant Hollow Carbon–Silica Nanospheres

Hollow carbon–silica nanospheres that exhibit angle‐independent structural color with high saturation and minimal absorption are made. Through scattering calculations, it is shown that the structural color arises from Mie resonances that are tuned precisely by varying the thickness of the shells. Since the color does not depend on the spatial arrangement of the particles, the coloration is angle independent and vibrant in powders and liquid suspensions. These properties make hollow carbon–silica nanospheres ideal for applications, and their potential in making flexible, angle‐independent films and 3D printed films is explored.     

Magnetic hollow mesoporous silica nanospheres: facile fabrication and ultrafast immobilization of enzymes

Hollow mesoporous silica nanospheres with large pore size of around 11 nm have been synthesized by a structural difference based selective etching strategy, and the highly dispersed hydrophobic Fe3O4 nanoparticles with a particle size of 5 nm were then impregnated into hollow cores of nanospheres through these large pores by a vacuum impregnation technique. The structural characteristics of obtained magnetic composites were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Selected Area Electron Diffraction (SAED), Ultraviolet-visible (UV-Vis) and Vibrating Sample Magnetometer (VSM). The results show that the obtained Fe3O4-hollow mesoporous silica composites exhibit superparamagnetic property with saturation magnetization value of 4.17 emu/g. Furthermore, the obtained supports show ultrafast immobilization of hemoglobin and the immobilized enzymes are not denatured, indicating that the superparamagnetic hollow mesoporous silica spheres are excellent support for immobilization of enzymes with magnetic recycling property.     

Template synthesis, organic gas-sensing and optical properties of hollow and porous In(2)O(3) nanospheres

Hollow and porous In(2)O(3) nanospheres have been prepared by the hydrolysis of InCl(3) using carbonaceous spheres as templates in combination with calcination. Based on the observation of scanning electronic microscopy (SEM) and transmission electron microscopy (TEM), it has been revealed that the as-prepared In(2)O(3) nanospheres have a uniform diameter of around 200?nm and hollow structures with thin shells of about 30 nm consisting of numerous nanocrystals and nanopores. Owing to the hollow and porous structures, In(2)O(3) nanospheres possessing more active surface area exhibit a good response and reversibility to some organic gases such as methanol, alcohol, acetone and ethyl ether. In addition, the response mechanism of hollow and porous In(2)O(3) nanospheres to organic gases has been proposed. Furthermore, these prepared In(2)O(3) spheres showed a UV-visible absorption peak centered at around 309?nm, and their photoluminescence spectra have also been investigated.     

Solvothermal synthesis of solid and hollow CoO nanospheres and their electrochemical properties in lithium-ion battery

Solid and hollow CoO nanospheres were synthesized by solvothermal method with oleic acid as reactant and SiO₂ as template. Each sample of high-purity CoO was characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron energy spectroscopy, respectively. Both solid and hollow CoO nanospheres as anode for lithium-ion battery were tested by galvanostatic discharge–charge experiments. The first discharge capacity of 1598 and 1640 mAh g^?1 was obtained at 0.1C for solid and hollow CoO nanospheres, respectively. Hollow CoO nanospheres showed better cycle performance.     

Fabrication of raspberry-like superhydrophobic hollow silica particles

Raspberry-like superhydrophobic hollow silica particles were prepared through a sacrificial polymer template method. The Stöber method was adopted to coat silica onto the surface of cationic polymethylmethacrylate(PMMA) particles by electrostatic interaction. The surface of the PMMA-silica composite particles exhibited raspberry-like morphology with high surface roughness. Hollow silica particles were then obtained by calcination to selectively remove the PMMA core. Subsequent modification with nonafluorohexyltriethoxysilane (NFH-silane) conferred superhydrophobicity on the hollow silica particles. The surface property of this particles were investigated by measuring their water contact angle, and the results showed that such perfluorinated raspberry-like hollow particles had unique superhydrophobic.     

无机材料纳米空心球的制备方法研究进展

探索新的纳米结构已成为近年来物理、化学、材料等领域的研究热点之一.纳米空心球作为一种新的纳米结构,其特有的核-壳空心结构及纳米厚度的壳层使它具有许多优异的物理化学性能,从而在医学、制药学、材料学、染料工业等领域具有很好的应用前景.本文综述了模板法和由模板法发展而来的L-bL自组装法制备无机材料纳米空心球的一般过程及原理,最后展望了纳米空心球材料的发展前景,并探讨了目前在无机材料纳米空心球研究领域中存在的问题.     

Characterization of hollow silica–polyelectrolyte composite nanoparticles by small-angle X-ray scattering

Hollow silica–polyelectrolyte composite nanoparticles were prepared using templates of spherical polyelectrolyte brushes which consist of a polystyrene (PS) core and a densely grafted linear poly(acrylic acid) shell. The obtained hollow particles were systematically studied by small-angle X-ray scattering (SAXS) in combination with other characterization methods such as transmission electron microscopy and dynamic light scattering. The hollow structure formed by dissolving the PS core was confirmed by the reduction of electron density to zero in the cavity through fitting SAXS data. SAXS revealed both the inward and outward expansions of the hollow silica–polyelectrolyte composite particles upon increasing pH from 3 to 9, while further increasing pH led to the partial dissolution of silica layer and even destruction of the hollow structure. SAXS was confirmed to be a unique and powerful characterization method to observe hollow silica nanoparticles, which should be ideal candidates for controlled drug delivery.