1、纳米材料的湿法合成DOC论文中英文摘要作者姓名：孙旭平 论文题目：纳米材料的湿化学合成及新颖结构的自组装构建作者简介：孙旭平，男，1972年08月出生，2000年09月师从于中国科学院长春应用化学研究所汪尔康研究员，于2006年03月获博士学位。中 文 摘 要围绕论文题目“纳米材料的湿化学合成及新颖结构的自组装构建”，我们开展了一系列研究工作。通过湿化学途径，在贵金属纳米粒子及其二维纳米结构和导电聚合物纳米带的合成方面进行了深入研究。同时，利用界面自组装及溶液自组装技术，构建了一些新颖结构。本论文研究工作的主要内容和创新点表现在以下几个方面：(1) 首次提出了一步加热法制备多胺化合物保护的贵金
2、属纳米粒子。我们利用多胺化合物(包括聚电解质和树枝状化合物)作为还原剂和保护剂，直接加热贵金属盐和多胺化合物的混合水溶液，在不加入其它保护剂和还原剂的情况下，一步制备得到了稳定的贵金属金和银的纳米粒子。我们在实验中发现，树枝状化合物聚丙烯亚胺能对反应生成的金纳米粒子的大小及成核和生长动力学进行有效控制。我们还发现，室温下直接混合浓的阳离子聚电解质分支型聚乙烯亚胺和浓的HAuCl4水溶液可得到高浓度的、稳定的胶体金。这种一步合成法操作简单且方便易行，是一种制备多胺化合物保护的贵金属纳米粒子的通用方法；同时，本方法合成的纳米粒子表面带正电荷，可用作加工纳米粒子功能化薄膜的构建单元。(2) 首次提出
3、了一种无表面活性剂的、无模板的、大规模制备导电聚合物聚邻苯二胺纳米带的新方法。我们通过在室温下直接混合邻苯二胺和HAuCl4水溶液，在没有表面活性剂或“硬模板”存在的条件下，获得了长度为数百微米、宽度为数百纳米、厚度为数十纳米的聚邻苯二胺。纳米带的自发形成可归因于反应中生成的金纳米粒子催化的邻苯二胺的一维定向聚合。本方法方便快速，无需加入表面活性剂或使用“硬模板”，且可用于大规模制备。此外，我们通过在室温下直接混合AgNO3和邻苯二胺水溶液，也获得了大量的一维纳米结构，并发现其形貌可通过调节实验参数而改变。我们还发现，当溶液pH降低时，这些一维结构将分解成水溶性的低聚体，而如果再次升高pH，这
4、些低聚体又将自组装形成一维纳米结构。各种数据表明，这种一维纳米结构是由邻苯二胺被AgNO3氧化后所生成的低聚体在溶液中自组装而形成的。(3) 发展了一系列可大量制备沿(111)晶面优先生长的单晶金二维结构(包括纳米片及微米盘)的湿化学合成方法。在室温下直接混合HAuCl4和邻苯二胺水溶液，我们得到了大量的、呈六角形的、纳米厚度的单晶金片，其尺寸达1.5m，邻苯二胺和HAuCl4间的摩尔比是纳米片形成的关键，这种纳米片不仅能应用于光学领域，还可用于加工具有独特机械性能的新型结构材料。我们通过直接加热浓的HAuCl4和线型聚乙烯亚胺混合水溶液，也获得了大量的金纳米单晶片，其尺寸可达40m，反应物浓
5、度是获得纳米片的关键因素，这种具有大的(111)晶面的单晶金片有望用做扫描隧道显微镜(STM)的基底。此外，通过加热草酸-HAuCl4混合水溶液，我们还得到了大量的、尺寸达4m的、呈六角形的金二维结构，但其厚度大于100 nm，为微米盘，其大小和厚度可通过草酸的用量得到控制。(4) 发展了一种基于溶液中的配位组装的、室温下方便合成有机-无机配位聚合物杂化材料的单分散亚微米胶体球的新方法。在室温下直接混合H2PtCl6和对苯二胺水溶液，通过对苯二胺和PtCl62-在溶液中的配位自组装，我们得到了亚微米尺寸的、单分散的、配位聚合物球形胶体球。实验表明，粒子大小和多分散度可由反应物间的摩尔比和浓度进
6、行控制，获得单分散胶体球的最佳实验条件是1:1摩尔比和适中的浓度。本研究结果具有比较重要的意义：(1) 它提供了一个温和的、室温条件下获得单分散胶体粒子的合成方法，从而避免了获得单分散的无机材料胶体粒子所必须的高温反应条件；(2) 这种胶体粒子是一种新的杂化材料，它结合了两种组分的优点而具有多种属性，因而可用在许多领域；(3) 这种胶体粒子在强还原剂如NaBH4 存在的情况下，由于其中的Pt阳离子组分被还原而发生分解，因此可用做易分解的胶体粒子模板加工中空球。此外，我们通过室温下直接混合邻苯二胺的N-甲基吡咯烷酮溶液和AgNO3水溶液，得到了亚微米的球形银胶体粒子(平均粒径达850 nm)。实
7、验结果还表明，升高温度有利于更大尺寸的银粒子的生成，溶剂对纯的银粒子沉淀物的获得起着比较关键的作用。这些亚微米粒子的形成经历了两个阶段：(1) 超饱和溶液中纳米主粒子的成核；(2) 形成的主粒子聚集成更大的均匀的粒子。(5) 我们发展了一种在表面巯基功能化的电极表面有效固定Ru(bpy)32+的新方法。本方法同时运用了溶液自组装和固体表面自组装两种技术，即：先将Ru(bpy)32+和柠檬酸根阴离子保护的金纳米粒子的水溶液按照一定比例混合，得到了Ru(bpy)32+-金纳米粒子聚集体，然后把少量聚集体的悬浮液直接滴在表面巯基功能化的电极表面，从而实现Ru(bpy)32+在电极表面的有效固定。该方
8、法简单易行，制备的电极具有很好的稳定性和电化学发光性能，因而在固态电化学发光检测方面具有很好的应用前景；此外，该方法还可用于在固体表面构建Au纳米粒子多层膜。(6) 发展了一种通过加热3-噻吩丙二酸(3-thiophenemalonic acid, TA)和H2PtCl6混合水溶液直接制备小的Pt纳米粒子的新方法，并通过对该胶体溶液用Ru(bpy)32+处理，得到了Ru(bpy)32+-Pt纳米粒子聚集体。通过对在裸电极表面的聚集体进行循环电势扫描，使得聚集体中的TA分子发生电化学聚合而在电极表面形成了稳定的聚合物膜；由于该膜有效地避免了聚集体从电极表面脱落，从而我们得到了非常稳定的、具有极好
9、电化学发光性能的膜。本工作不但提供一种方便制备Pt纳米粒子的新途径，而且还发展了一种在任何表面直接加工电化学发光检测器的新方法，在固态电化学发光检测方面具有重要应用价值。(7) 通过在室温下直接混合H2PtCl6和Ru(bpy)3Cl2水溶液，我们获得了具有新颖形貌的、含有Ru(bpy)32+的微结构。实验结果表明，金属价态、金属种类及反应物摩尔比和浓度对微结构的形貌有重要影响，形成的微结构都具有很好的电化学发光性能。这些微结构给我们提供了一种新的功能材料，将在毛细管电泳或毛细管电泳微芯片的固态电化学发光检测方面有着很好的应用前景。关键词： 纳米材料，湿化学，自组装，电化学发光Wet-Chem
10、ical Routes to the Preparation of Namomaterials and Self-Assembly-Based Fabrication of Novel StructuresSun XupingABSTRACTBoth the wet-chemical preparation of nanomaterials and self-assembly-based fabrication of novel structures have been paid considerable attention. We carried out several studies on
11、 the preparation of noble metal nanoparticles and its two-dimensional nanostructures and conducting polymers nanobelts via wet-chemical routes. On the other hand, we fabricated some novel structures through self-assembly on planar solid substrates or in solutions. Especially, the application of some
12、 structures in the field of solid-state electrochemiluminescence detection is also explored. We have developed a heat-treatment-based strategy for the one-step preparation of polyamine-protected noble metal nanoparticle. With the use of third-generation poly(propyleneimine) (PPI G3) dendrimer to sim
13、ultaneously act both as the reducing agent and protective agent, stable noble metal gold nanoparticles have spontaneously formed by heating a solution containing HAuCl4 and PPI G3. As a result, an additional step of introducing a reducing agent as well as a protective agent is no longer needed. It i
14、s found that the size, the nucleation and growth kinetics of the gold nanoparticles thus formed can be tuned by changing the initial molar ratio of PPI G3 to gold. Similarly, highly stable Ag nanoclusters with narrow size distribution have been prepared by heating a AgNO3/PPI G3 aqueous solution wit
15、hout the additional step of introducing other reducing agents and protect agents. It is found that as-obtained particle is in coexistence of Ag and Ag2O and increasing temperature results in both the decrease in number of small particles and the increase in size of large particles. In addition, such
16、 thermal process has been successfully used to prepare amine-functionalized polyelectrolyte-protected gold nanoparticles by directly heating an aqueous solution containing HAuCl4 and polyelectrolytes. Four polyelectrolytes including N-3-(trimethoxysilyl)propylpolyethylenimine (Si-PEI), branched poly
17、ethylenmine (BPEI), linear polyethylenimine (LPEI) and poly(allylamine hydrochloride) (PAH) were used in our study and well-stabilized gold nanoparticles with relatively narrow size distribution were obtained. Because gold nanoparticles thus formed can be combined with the properties of the polyelec
18、trolytes used, they hold promise for use in the biomedical and bioanalytical field and on the other hand, as building blocks for the creation of nanoparticles-containing thin films. This strategy will be general to other polyelectrolytes with the same chemical structure as these four polyelectrolyte
19、s used and to the preparation of other nanoparticles such as Ag nanoparticles. Furthermore, we have found that highly concentrated, well-stable gold colloids can be prepared by direct mix of concentrated HAuCl4 and BPEI aqueous solutions at room temperature.We have developed for the first time a nov
20、el but simple surfactantless, templateless method for preparing conducting polymer poly(o-phenylenediamine) nanobelts on a large scale. The mix of HAuCl4 and o-phenylenediamine aqueous solutions at room temperature results in the formation of a large quantity of precipitate. Lower magnification scan
21、ning electron microscopy (SEM) image indicates that the precipitate consists of a large quantity of uniform one-dimensional structures. Higher magnification SEM image further reveals these structures are transparent nanobelts with several hundred micrometers in length, several hundred nanometers in
22、width, and several ten nanometers in height. Also observed in these SEM images are a number of nanoparticles. The X-ray diffraction (XRD) analysis of the resulting precipitate reveals the formation of amorphous poly(o-phenylenediamine) polymers with larger crystalline size as well as crystalline gol
23、d. Elemental analysis of the resulting precipitate using secondary electrons by SEM indicates the belts are poly(o-phenylenediamine) polymers but the particles are gold particles. The possible formation of the nanobelts can be explained as follows: The reduction of HAuCl4 by o-phenylenediamine leads
24、 to the formation of gold nanoparticles with the occurrence of o-phenylenediamine oligomers first, then gold nanoparticles produced serve as active catalysts to catalyze the oriented oxidative polymerization of other o-phenylenediamine monomers by HAuCl4 along the oligomers produced, resulting in th
25、e formation of poly(o-phenylenediamine) nanobelts. Furthermore, we have found that mixing of AgNO3 and o-phenylenediamine in aqueous medium results in the formation of uniform one-dimensional structures. However, the formation of such 1D structure involves the following two stages: (1) The oxidation
26、 of o-phenylenediamine by AgNO3 leads to the formation of individual o-phenylenediamine oligomers. (2) The resulting individual oligomers self-assembly to form uniform larger 1D structures. Interestingly, decreasing medium pH can break these 1D structures apart to form individual oligomers, or vice
27、versa. It is also found that both the concentration and molar ratio of reactants have considerable influences on the morphologies of the structures thus formed.We have developed several wet-chemical approaches for the large-scale preparation of two-dimensional, single-crystalline gold structures inc
28、luding nanoplates and microdisks. The mix of an appropriate volume of an aqueous solution of freshly prepared o-phenylenediamine and HAuCl4 at room temperature with 1:1 molar ratio of o-phenylenediamine to gold gradually leads to a large quantity of precipitate, which is collected by centrifugation,
29、 washed several times with THF and water, and then suspended in water. The lower magnification SEM image indicates that the precipitate consists of a large amount of particles, while the higher magnification SEM image clearly reveals that the particles are micrometer-scale plates (about 1.5 m in siz
30、e), mainly hexagonal in shape. The distance between two planes of one plate standing against the glass substrate indicates that these plates are nanoplates. The corresponding energy-dispersive X-ray spectrum (EDS) shows these nanoplates are pure metallic gold. Two surface plasmon absorption bands at
31、 about 680 and 925 nm which arise from the longitudinal plasmon resonance of gold particles are observed for these gold nanoplates, providing another piece of evidence for the formation of anisotropic gold particles. It suggests that the quantity of o-phenylenediamine in the solution is crucial to y
32、ielding gold nanoplates and we may suggest that o-phenylenediamine molecules serve as a soft template and kinetically control the growth rates of various faces of gold particles by selectively adsorbing on to the crystallographic planes, thus resulting in the formation of large single-crystalline go
33、ld nanoplates. The importance of the platelet-like gold particles is not restricted to optics; exceptionally interesting materials with unique mechanical properties can be obtained with such colloids. A polyamine process has also been successfully used for the high-yield preparation of single-crystalline gold nanoplates with several 10m in siz
