亲水有机相-含盐水两相体系的形成机理与分相能力

亲水有机相-含盐水两相体系的形成机理与分相能力;亲水有机相;含盐水相;两相体系;分相机理;分相能力     

CdSe电沉积层的组成及形成机理

伏安曲线和现场光电流测定用于研究在钛基体上阴极电沉积形成Cdse薄膜的机理. XPS实验表明, CdSe沉积层的组成与沉积电位、沉积时间和溶液组成有关.在0.1 mol·L~(-1)CdSO_4+4 mmol·L~(-1)H_2SeO_3+0.2 mol·L~(-1) H_2SO_4溶液中, 当电位比-0.50 V正时生成富Se层, 而当电位比-0.70 V还负时生成富Cd层. 在-0.69 V下沉积, 沉积层的Se/Cd计量比接近1.1. 在同一电位下, 若提高H_2Se0_3浓度, 则沉积物中Se的含量增多. 实验结果表明, CdSe电沉积因条件不同遵循两种不同的机理, 据此讨论了克服Se/Cd比大于1的可能措施。     

束状纳米二氧化硅的快速制备

在水醇体系中,以十六烷基三甲基溴化铵为模板,通过氨催化正硅酸乙酯水解,快速合成了束状纳米二氧化硅．用透射电子显微镜观察了束状二氧化硅的形貌,讨论了反应时间和十六烷基三甲基溴化铵的浓度对其形貌的影响,确定了束状二氧化硅形成的最佳条件,并提出了束状结构的形成机理．     

胆结石组成和形成机理的研究进展

综述了利用多种方法(如: F T-IR, Raman, NMR, EPR, 凝胶色谱, 元素分析, ICP, 原子吸收谱, 差热-热重谱, X射线荧光分析, EXAFS及XRD等)对胆结石组成和形成机理进行研究的进展. 结果表明, 胆结石中含有多种生物小分子、生物大分子(如蛋白等)、金属离子, 以及具有非化学计量特征的胆红素络合物等. 金属离子与胆盐的相互作用与结石沉淀的形成密切相关. 从结石截面可以看到环状结构, 所以利用体外模拟实验对结石的形成机理进行了研究, 并将非线性的科学概念引入到结石的形成机理中, 提出结石生长不是逐层生成沉淀, 而是首先生成周期环形模板的观点.     

磁性金属纳米管的制备、形成机理及潜在应用

磁性金属纳米管因其独特的中空结构和优异的催化、磁性及易修饰等性能,逐步发展成为一类重要的功能纳米材料,受到国内外研究人员的广泛关注。本文综述了近年来模板法制备磁性金属纳米管的主要技术,如电沉积、化学沉积、湿模板、原子沉积及水热合成等,重点阐述了硬模板法制备磁性金属纳米管的特殊策略,并针对不同制备策略下的磁性金属纳米管形成机理进行了评述。另外,对硬模板法合成磁性金属纳米管建立了一个机理模型,分别从基底性能、成核环境、生长环境三方面对磁性纳米管的形成机理进行了探讨。最后简单介绍了磁性金属纳米管的性能及潜在应用,并展望了该领域的发展趋势。     

自由基交联共聚合体系凝胶点和凝胶形成机理

通过分析几个有代表性的单烯／二烯自由基交联模型的计算机模拟结果，认为凝胶点判据和凝胶形成机理是两个相互联系但决不相同的概念。将体系中首次出现分子平均交联密度等于１／ＤＰｐｗ的分子作为凝胶点判据。凝胶形成过程可分为成核与生长两个阶段，成核条件为溶胶分子平均交联密度等于１／ＤＰｐｗ。     

线团式纳米NaY分子筛复合材料的制备及形成机理

通过在偏高岭土水热合成NaY分子筛的晶化过程中加入乙醇的方法,制备了线团式纳米NaY分子筛复合材料,用XRD、SEM、ICP OES研究了晶化过程中固液相结构和组成的变化,初步探讨了其形成机理,提出了制备纳米NaY分子筛复合材料的条件.     

氮化硼纳米管的研究进展

本文较全面地综述了氮化硼(BN)纳米管研究的最新进展,详细讨论了BN纳米管的合成、结构、表征、形成机理及应用等方面的研究现状,并对今后的研究方向进行了展望。     

不同形貌纳米二氧化硅的制备及形成机理研究

在水醇体系中,以正硅酸四乙酯(TEOS)作为硅源、氨水作为催化剂,快速合成了哑铃状、纤维状及链状3种形貌的纳米SiO2;利用透射电子显微镜分析了产物的微观结构,着重探讨了氨水浓度、TEOS浓度及TEOS滴加速度对纳米SiO2形貌的影响,并提出了不同形貌纳米SiO2的形成机理.     

水解胶原蛋白热氧化及CaSO4形成机理探讨

水解胶原蛋白热氧化及CaSO4形成机理探讨;水解胶原蛋白; L-抗坏血酸; H2O2; 热氧化; CaSO4     

银纳米棱镜的形成及其光学性能研究

以有机溶剂作为反应介质,聚合物为稳定剂,通过微波辅助溶液法成功地制备了具有特殊光学性能的银纳米棱镜.利用X射线衍射、透射电子显微镜和紫外-可见光谱等手段跟踪反应过程.结果显示,随着反应的进行,银纳米粒子由10nm左右的球形颗粒逐渐转变为具有规则三角形(或缺角的三角形)形貌的纳米棱镜;同时,紫外-可见吸收峰不但显示出明显的量子尺寸效应,而且吸收峰也由单一的等离子共振吸收峰变为多重的多极吸收峰共同存在,胶体溶液也随之显示出不同的颜色.改变反应物的配比、体系的浓度及无机前驱物都会得到位置和峰形各不相同的吸收曲线,从而得到多彩的纳米银胶体溶液.     

Ultrasonically induced Au nanoprisms and their size manipulation based on aging

A simple sonochemical approach was developed for the synthesis of single-crystal Au nanoprisms with triangular or hexagonal shape, 30-40 nm planar dimension, and 6-10 nm thickness in an ethylene glycol solution. It has been shown that ethylene glycol, the surfactant poly(vinylpyrrolidone), and ultrasonic irradiation play important roles in the formation of Au nanoprisms. The subsequent aging induces the growth of Au nanoprisms, which is attributed to the existence of residual reduced Au degrees atoms and Au clusters in the solution. Further growth of Au nanoprisms could be realized by adding a given amount of HAuCl4 to the irradiated and aged Au nanodisk colloidal solution, which provides a simple and an effective method to synthesize Au nanoprisms with different sizes. Au nanoprisms with planar sizes from 70 to 400 nm have been successfully synthesized based on this strategy.     

Structural Study of the Photo-Mediated Growth of Silver Nanoprisms

We present a small-angle X-ray scattering (SAXS) study of the anisotropic photoinduced growth of silver (Ag) nanoprisms in aqueous dispersions. The growth of nearly spherical (<10 nm) Ag particles into large (>40 nm) and thin (<10 nm) triangular nanoprisms induced by 550 nm laser is followed in terms of particle size using indirect and direct methods for irradiation times up to 150 min. During the process, the surface-to-volume ratio of the particles decreased. The SAXS data of the initial solution fit well to the model of polydisperse spheres with pronounced average diameters around 7.4 nm and 10 nm. The data after 45 min irradiation fit well to the model containing approximately the same amount of the initial particles and the end product, the nanoprisms.     

Controllable synthesis of ZnO nanorod and prism arrays in a large area

ZnO nanorod and nanoprism arrays have been directly synthesized on a large-area zinc substrate via a convenient solution method. The products were characterized with XRD, SEM, HRTEM, and photoluminescence (PL) spectroscopy. The influence of the solvent and the concentration of NaOH on the size and shapes of the as-prepared ZnO samples have been studied. It was found that ZnO nanorod or nanowire arrays were fabricated in alcohol, whereas ZnO nanoprisms with pyramid tips were produced in an alcohol-water mixture. The diameters of the nanorods or nanoprisms became thicker when a higher concentration of NaOH was used. Room-temperature PL spectra of the ZnO products showed a UV emission and a broad green band. The mechanism of the nanorods and nanoprisms in two systems is briefly discussed.     

Tailoring the synthesis and heating ability of gold nanoprisms for bioapplications

The paper describes a novel and straightforward wet-chemical synthetic route to produce biocompatible single-crystalline gold tabular nanoparticles, herein called nanoprisms (NPRs) due to their characteristic shape. Besides the novelty of the method to produce NPRs with an unprecedented high yield, the synthesis avoids the use of highly toxic cetyltrimethylammonium bromide (CTAB), the most widely used surfactant for the synthesis of gold anisotropic nanoparticles such as nanorods or nanoprisms. The method presented here allows for tuning the edge length of NPRs in the range of 100-170 nm by adjusting the final concentration/molar ratio of gold salt and reducing agent (thiosulfate), while the thickness of NPRs remained constant (9 nm). Thus, the surface plasmon band of NPRs can be set along the near-infrared (NIR) range. The resulting NPRs were derivatized with heterobifunctional polyethylene glycol (PEG) and 4-aminophenyl β-D-glucopyranoside (glucose) chains to improve their stability and cellular uptake, respectively. The heating properties of colloidal solutions of NPRs upon 1064 nm light illumination were evaluated. As a proof of concept, the biocompatibility and suitability of functional NPRs as photothermal agents were studied in cell cultures. Due to their biocompatibility (avoiding CTAB), ease of production, ease of functionalization, and remarkable heating features, the NPRs discussed herein represent a significant advance in the biocompatibility of nanoparticles and serve as an attractive alternative to those currently in use as plasmonic photothermal agents.     

Boron and nitrogen-codoped TiO2 nanorods: Synthesis, characterization, and photoelectrochemical properties

Boron and nitrogen codoped TiO₂ nanorods (BNTRs) were synthesized via two-step hydrothermal reactions using TiN as a starting material. The as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscope (SEM), transmission electron microscopy and X-ray photoelectron spectroscopy techniques. The results showed that TiO₂ nanorods with the diameter of approximately 50–100 nm and the length of several micrometers were doped by the interstitial N and B. The nanorods were firstly formed in the hydrothermal synthesis of nitrogen doped TiO₂. The growing process of nanorods was observed by SEM and a most probable formation mechanism of the trititanate nanorods was proposed. The BNTRs showed a higher photocatalytic activity and a bigger photocurrent response than N–TiO₂ nanorods under visible light irradiation.     

二元混合表面活性剂用于窄吸收金纳米棒的无种子合成

利用十六烷基三甲基溴化铵(CTAB)和油酸钠(NaOL)二元混合表面活性剂体系, 开发了一种高质量金纳米棒(AuNRs)的无种子合成方法. 通过透射电子显微镜(TEM)、 紫外-可见-近红外吸收光谱(UV-Vis-NIR)和热成像仪对金纳米棒的形貌、 光学性质及光热性能进行了表征. 实验结果表明, 当NaOL浓度为8.21~11.5 mmol/L时, 能够获得形貌均匀的AuNRs, 其纵向表面等离子体共振吸收(LSPR)在650~1150 nm范围内可调. 该方法制得的样品具有较窄的LSPR半峰宽, 特别是在制备LSPR在近红外二区(NIR-II, 大于1000 nm)的AuNRs方面具有明显优势. 在1064 nm激光的辐照下, 金纳米棒溶液能够快速升温至67 ℃, 光热转换效率可达31.5%, 同时表现出优秀的光热稳定性, 在近红外二区光声成像和光热治疗方面具有良好的应用价值.     

Sonochemical fabrication and characterization of stibnite nanorods

Regular stibnite (Sb(2)S(3)) nanorods with diameters of 20-40 nm and lengths of 220-350 nm have been successfully synthesized by a sonochemical method under ambient air from an ethanolic solution containing antimony trichloride and thioacetamide. The as-prepared Sb(2)S(3) nanorods are characterized by employing techniques including X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, selected area electron diffraction, high-resolution transmission electron microscopy, and optical diffuse reflection spectroscopy. Microstructural analysis reveals that the Sb(2)S(3) nanorods crystallize in an orthorhombic structure and predominantly grow along the (001) crystalline plane. High-intensity ultrasound irradiation plays an important role in the formation of these Sb(2)S(3) nanorods. The experimental results show that the sonochemical formation of stibnite nanorods can be divided into four steps in sequence: (1) ultrasound-induced decomposition of the precursor, which leads to the formation of amorphous Sb(2)S(3) nanospheres; (2) ultrasound-induced crystallization of these amorphous nanospheres and generation of nanocrystalline irregular short rods; (3) a crystal growth process, giving rise to the formation of regular needle-shaped nanowhiskers; (4) surface corrosion and fragmentation of the nanowhiskers by ultrasound irradiation, resulting in the formation of regular nanorods. The optical properties of the Sb(2)S(3) amorphous nanospheres, irregular short nanorods, needle-shaped nanowhiskers, and regular nanorods are investigated by diffuse reflection spectroscopic measurements, and the band gaps are measured to be 2.45, 1.99, 1.85, and 1.94 eV, respectively.     

Synthesis of temperature and pH-responsive crosslinked micelles from polypeptide-based graft copolymer

We report a method for synthesizing small-diameter ZnO nanorods at room temperature (20 °C), under normal atmospheric pressure (1 atm), and using a relatively short reaction time (1 h) by adding gallium salts to the reaction solution. The ZnO nanorods were, on average, 92 nm in length and 9 nm in diameter and were single crystalline in nature. Quantitative analyses revealed that gallium atoms were not incorporated into the synthesized nanocrystals. On the basis of the experimental results, we propose a mechanism for the formation of small-diameter ZnO nanorods in the presence of gallium ions. The optical properties were probed by UV-Vis diffuse reflectance spectroscopy. The absorption band of the small-diameter ZnO nanorods was blue-shifted relative to the absorption band of the ~230 nm diameter ZnO nanorods (control samples). Control experiments demonstrated that the absence of metal ion-containing precipitants (except ZnO) at room temperature is essential, and that the ZnO nanorod diameter distributions were narrow for the stirred reaction solution and broad when prepared without stirring.     

Organo-soluble chiral thiol-monolayer-protected gold nanorods

Here, we report the synthesis and characterization of organo-soluble chiral thiol-monolayer-protected gold nanorods. The resulting gold nanorods respectively covered with two opposite enantiomers via the strong covalent Au-S linkage were found to not only be stable in both organic media and solid state, but also show optical activity. Their circular dichroism (CD) spectra exhibited a mirror image relationship, indicating that enantiomeric thiol surfactant on gold surface can produce the corresponding enantiomeric gold nanorods. The densely packed azobenzene thiol monolayer on gold surface exhibited a photoresponsive behavior upon irradiation with 254 nm light instead of 365 nm light, which was found to have an effect on plasmonic absorption of gold nanorods.