基于微流控技术制备微/纳米粒子材料

具有特殊性质的微/纳米粒子,在药物传递、吸收分离、光电材料和磁性设备等多个领域具有重要的应用价值。近年来,微流控技术在有机合成、高分子化学以及材料制备等领域表现出传统釜式反应器无法比拟的优势。本文介绍了基于微流控技术制备微/纳米粒子的最新研究进展,包括以单乳液为模板合成球形和非球形聚合物粒子、无机物粒子、贵金属纳米粒子和半导体纳米粒子,以多重乳状液为模板制备壳核粒子、Janus粒子和微囊。     

硅化物纳米线阵列的制备、表征和性能研究

一维纳米材料因其特殊结构引起的新奇的物理和化学性质以及诱人的应用前景而备受关注.已经发展了多种制备一维纳米材料的方法,其中,模板法是一种制备纳米线阵列的常用方法,这种方法已经被成功地用于多种材料纳米线阵列的制备.金属离子辅助的溶液刻蚀方法可以在温和反应条件下大规模制备Si纳米线阵列,是一种重要的制备Si纳米线的手段.本论文用化学刻蚀方法得到的Si纳米线阵列作为模板和Si源,成功地制备出了多种硅化物的纳米线阵列,包括SiC、Mn₂₇Si₄₇和NiSi,对其结构进行了详细的表征,并在性能研究的基础上探索了其可能的应用.     

金属辅助化学刻蚀法制备硅纳米线及应用

金属辅助化学刻蚀是近些年发展起来的一种各向异性湿法刻蚀,利用该方法可以制备出高长径比的半导体一维纳米结构。 本文综述了金属辅助化学刻蚀法可控制备硅纳米线的最新进展,简要概述了刻蚀的基本过程与机制,重点阐述了基于不同模板的金属辅助化学刻蚀可控制备高度有序、高长径比的硅纳米线阵列的具体流程与工艺,并介绍了其在锂离子电池、太阳能电池、气体传感检测和仿生超疏水等方面的潜在应用,探讨了目前存在的问题及其今后的研究发展方向。     

银辅助刻蚀单晶硅

结合高中化学原电池、氧化还原反应以及银镜反应等知识,介绍两种沉积银粒子辅助刻蚀单晶硅技术的基本原理,供一线高中化学教师用于扩展高中生的化学知识,帮助学生了解化学前沿。     

利用XPS 氩离子刻蚀表征锂离子电池Si/C负极材料中含硅的活性物质

以石墨、沥青和纳米硅粉为原料制备了锂离子电池Si/C负极材料,使用SEM/ BSE 、Raman、XRD、XPS及XPS氩离子刻蚀等方法对其硅活性物质进行了具体分析。结果表明,XRD和Raman仅判断出负极材料中含有活性物质单质Si;常规XPS结果发现近一半的Si已被氧化为惰性物质SiO2;而使用XPS氩离子刻蚀方法发现负极材料中Si存在5种化学态,包括活性物质单质Si、Si2O、SiO、Si2O3,及惰性物质SiO2;定量结果表明,复合材料的硅活性物质高于96.56%,且主要结构是低价态硅氧化物,而非单质Si。XPS氩离子刻蚀的分析方法为锂离子电池负极材料中硅活性物质的研究提供了新思路。     

镍表面三维微图形的复制加工

运用约束刻蚀剂层技术(CELT)在金属镍(Ni)表面实现三维微图形加工,以规整的三维齿状微结构作模板,获得可有效CELT加工的化学刻蚀和捕捉体系,在Ni表面得到了与齿状结构互补的三维微结构并应用扫描电子显微镜(SEM)和原子力显微镜(AFM)表征刻蚀图案,证实CELT可用于金属表面Ni的三维微图形刻蚀加工．     

多肽在贵金属纳米粒子制备中的应用

由于具有与大块固体相迥异的性能,贵金属纳米粒子的制备与应用已经成为当前纳米、材料技术领域研究的热点。由于组成成分较多、包含各种活性基团、序列可调,并且很多多肽可生物降解、生物兼容、具有生物活性和特异性识别性能,多肽在贵金属纳米粒子制备中的应用也越来越受到人们的重视。本文从多肽作为还原剂还原贵金属盐; 多肽作为保护剂/调控剂制备不同尺寸/形貌的贵金属纳米粒子; 多肽作为引导剂规则排列贵金属纳米粒子; 多肽作为贵金属纳米粒子组装的模板以及多肽在贵金属表面的吸附、多肽的自组装和如何获取所需要的多肽序列等几个方面综述了近年来多肽在贵金属纳米粒子制备中的应用。最后简述了利用多肽制备的贵金属纳米粒子在纳米、材料技术领域中的应用,并提出了当前该领域中存在的一些不足及研究展望。     

基于宏观金属辅助化学刻蚀制备硅纳米线的研究

分别利用镀银的硅衬底和铂丝电极作为原电池反应中的阴极和阳极,基于金属辅助化学刻蚀采用宏观原电池的方法制备硅纳米线,深入研究了该法制备硅纳米线阵列的机理。通过改变电连接、镀银、刻蚀参数、硅衬底和光照等实验条件,系统地研究了所得硅纳米线形貌与其对应短路电流的关系,实验发现短路电流与硅纳米线长度有一定的对应关系。文章中所提出的模型旨在从根本上解决金属辅助化学刻蚀制备硅纳米线的机理。最后对这种方法所具有的潜在应用价值进行了展望和讨论。     

Pd/ZnO和Ag/ZnO复合纳米粒子的制备、表征及光催化活性

 用焙烧前驱物碱式碳酸锌的方法制备了ZnO纳米粒子，采用光还原沉积贵金属的方法制备了Pd／ZnO和Ag／ZnO复合纳米粒子，并利用ICP，XRD，TEM和XPS等测试技术对样品进行了表征，初步探讨了贵金属在ZnO纳米粒子表面形成原子簇的原因．以光催化氧化气相正庚烷为模型反应，考察了样品的光催化活性以及贵金属沉积量对催化剂活性的影响．结果表明：沉积适量的贵金属，ZnO纳米粒子光催化剂的活性大幅度提高．同时，深入探讨了表面沉积贵金属的ZnO纳米粒子光催化剂活性有所提高的内在原因．     

溶胶-凝胶法制备超亲水型低折射率膜层材料

以正硅酸乙酯(TEOS)为前驱体,乙醇为溶剂,氨水为催化剂,制备二氧化硅(Si O2)前驱体溶胶,并采用氢氟酸(HF)对溶胶中的球形Si O2粒子进行刻蚀改性,通过浸渍提拉法镀膜制备多孔Si O2膜层材料.研究结果表明,HF刻蚀后,多孔Si O2膜层材料的折射率明显降低,当HF的质量分数为3%时,膜层的折射率降低至1.101,膜层的静态接触角降低为3°,并且膜层的防雾性能得到显著提高.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.