以树形分子为模板制备银纳米颗粒

以硝酸银为原料，硼氢化钠为还原剂，PAMAM树形分子为模板兼稳定剂，制备出粒径分布范围在4～7mm的银纳米颗粒．实验发现，其他条件相同时，银纳米颗粒的粒径随着Ag^ ／树形分子摩尔比的增加而增加，并且树形分子代数越高，所起的模板作用越显著．还研究了溶液pH值的影响，发现当溶液pH值在7左右时，可以制得粒径较小、分散性较好的银纳米颗粒．用紫外-可见光谱，透射电镜(TEM)以及原子力显微镜(AFM)等测试手段对所制得的银纳米颗粒进行了表征．     

紫外光辐照下以PAMAM树形分子为模板制备Ag纳米簇及光致发光性能研究

以G5.0-OH PAMAM树形分子为模板,用紫外光辐照法制备银纳米簇.用透射电子显微镜、紫外-可见吸收光谱和共振散射光谱等对所制备的银纳米簇进行了表征.结果表明:用紫外光辐照法可以制备尺寸分布均匀、稳定的银纳米簇;且辐照时间、PAMAM树形分子的浓度及Ag⁺/PAMAM树形分子的摩尔比都会对所制备的银纳米簇产生较大的影响.由于所制备的银纳米簇的粒径小于树形分子的流体力学半径,表明树形分子起到了“内模板”作用.同时研究了银纳米簇的尺寸对其光致发光性能的影响,发现通过调节银纳米簇的尺寸可实现其光致发光的可调性.     

混合纳米氢氧化镍的球镍电极材料的电化学活性研究

采用配位沉淀法制备出了Ni(OH)₂样品，经XRD测试为β-Ni(OH)₂，TEM测试结果表明其为平均粒径50nm左右的不规则的颗粒。将所制备的纳米Ni(OH)₂按8wt%的比例在球镍中混合后制成电极，可使正极的比容量提高11%左右。热分析表明，纳米Ni(OH)₂的电化学活性高于球镍的电化学活性。激光拉曼光谱的测试结果说明了8wt%混合后制成的纳米电极确实有较好的放电容量，同时也证实了用拉曼光谱可以表征电极材料的充放电     

AgBr纳米簇：PAMAM树形分子模板法制备及光催化性能研究

以酯端基聚酰胺-胺(PAMAM)树形分子为模板，原位制备了AgBr纳米簇。由于酯端基的半代PAMAM树形分子起到“内模板”作用，制得的AgBr纳米簇粒径小、尺寸分布窄、稳定性好，并通过改变Ag⁺∶PAMAM树形分子的物质的量的比可以精确控制纳米簇的尺寸。AgBr纳米簇/树形分子纳米复合材料在光催化降解甲基橙方面具有很好的催化能力，且随纳米簇的尺寸减小，其催化能力增强。     

硫酸钡粒径调控剂C-N-CDs的制备、应用及机理

通过柠檬酸与乙二胺水热反应制备羧基、氨基修饰碳点(C-N-CDs),其具有优异的硫酸钡粒径调控作用：可使沉淀法制备的BaSO₄颗粒平均粒径减小到45.3 nm,小于同等条件下传统配位剂乙二胺四乙酸(EDTA)调控制备的BaSO₄颗粒平均粒径(73.7nm)。将所制备的纳米BaSO₄样品添加进聚乙烯醇(PVA)薄膜中可增强薄膜的力学性能。研究发现C-N-CDs的化学性能、表面电性、空间位阻是影响BaSO₄粒径大小的重要因素。     

PAMAM树形分子与Cd2＋的配位作用研究及CdS/PAMAM纳米复合材料的制备与表征

CdS半导体纳米簇具有独特的光、电性能, 如何制备均匀分散的、能够稳定存在的CdS纳米簇是目前的研究热点之一. 以聚酰胺-胺(PAMAM)树形分子为模板, 原位合成了CdS纳米簇. 首先用UV-Vis分光光度法研究了与树形分子的配位机理, 得出G4.5和G5.0的平均饱和配位数分别为16和34, 并发现在G4.5PAMAM树形分子中Cd^2＋主要与最外层叔胺基配位, 在G5.0PAMAM树形分子中Cd^2＋主要与最外层伯胺基配位. 酯端基的G4.5的模板作用要明显优于胺端基的G5.0. 通过改变Cd^2＋与G4.5树形分子的摩尔比可以得到不同粒径的CdS纳米簇. 溶液的pH值对CdS纳米簇影响很大, pH在7.0左右制备的CdS纳米簇粒径小而均匀, 且溶液稳定性高. 用UV-Vis分光光度计和TEM对CdS纳米簇的大小和形貌进行了表征. 结果表明TEM观测CdS纳米簇的粒径要大于用Brus公式的估算值.     

PAMAM树形分子与Cd2＋的配位作用研究及CdS/PAMAM纳米复合材料的制备与表征

CdS半导体纳米簇具有独特的光、电性能, 如何制备均匀分散的、能够稳定存在的CdS纳米簇是目前的研究热点之一. 以聚酰胺-胺(PAMAM)树形分子为模板, 原位合成了CdS纳米簇. 首先用UV-Vis分光光度法研究了与树形分子的配位机理, 得出G4.5和G5.0的平均饱和配位数分别为16和34, 并发现在G4.5PAMAM树形分子中Cd^2＋主要与最外层叔胺基配位, 在G5.0PAMAM树形分子中Cd^2＋主要与最外层伯胺基配位. 酯端基的G4.5的模板作用要明显优于胺端基的G5.0. 通过改变Cd^2＋与G4.5树形分子的摩尔比可以得到不同粒径的CdS纳米簇. 溶液的pH值对CdS纳米簇影响很大, pH在7.0左右制备的CdS纳米簇粒径小而均匀, 且溶液稳定性高. 用UV-Vis分光光度计和TEM对CdS纳米簇的大小和形貌进行了表征. 结果表明TEM观测CdS纳米簇的粒径要大于用Brus公式的估算值.     

PAMAM树形分子对CaCO3结晶影响的研究

研究了不同端基的聚酰胺胺(PAMAM)树形分子对CaCO₃在水溶液中结晶的影响。分别利用傅立叶变换红外光谱(FTIR)、X-射线衍射(XRD)、扫描电镜(SEM)等测试手段对样品进行了分析。结果表明:没有树形分子存在时CaCO₃是粒径为10μm的菱形方解石晶体;端基为-COONa的树形分子存在时CaCO₃则是粒径为1～2μm的球形球霰石晶体;-COOCH₃端基PAMAM树形分子存在时得到的CaCO_{3相似文献}   

WS2纳米颗粒的合成及摩擦学性能研究

将自制的WO₃纳米颗粒前驱体与S粉混合,在自制的反应装置氢气氛中,于550～750 ℃下煅烧得到二硫化钨纳米颗粒,反应中用H₂代替H₂S以减少对周围环境的污染。该合成路线简单且产物纯度高。用XRD、SEM、TEM和HRTEM对二硫化钨纳米结构进行了表征和分析,并将WS₂纳米颗粒作为添加剂添加到N40基础油中,在MS-T3000摩擦磨损仪测试其摩擦学性能。结果显示:制备的二硫化钨颗粒平均粒径在50 nm以内,其形状为球形或类球形。WS₂纳米颗粒作为普通润滑油的纳米级固体添加剂表现出了较优异的摩擦学性能。     

纳米金的制备及其在重金属离子检测中的应用——一个分析化学综合性研究型实验

具有可控粒径、形貌纳米金的制备是近年来的一大研究热点。本实验以铯盐硼簇(Cs₂B₁₂H₁₂)为还原剂和包覆剂,成功在水相中将氯金酸还原制备了纳米级别的单分散纳米金颗粒。并将制备得到的纳米金胶体应用于重金属离子(Cr₃₊和Pb₂₊)的比色法检测中,进一步利用紫外可见光谱可以对重金属离子实现定量检测。通过该实验,可以让学生学习制备纳米金的方法,掌握利用紫外等多种分析手段对纳米粒子结构及性能进行表征的技能。     

PVP and G1.5 PAMAM dendrimer co-mediated synthesis of silver nanoparticles

PVP and G1.5 PAMAM dendrimer co-mediated silver nanoparticles of smaller than 5 nm in diameter were prepared using H₂ as reducing agent. With the TEM micrograph, it was found that the molar ratios of PVP and G1.5 PAMAM dendrimer have significant effect in the morphology and size distribution of silver nanoparticles. The reaction rate (fitting a first-order equation) was strongly influenced by the molar ratios of PVP and G1.5 PAMAM dendrimer and the reaction temperature. From the UV-Vis spectra of an aqueous solution of silver nanoparticles, they could be stored for at least 2 months without coagulation at room temperature.     

Polymer particles with dendrimer@SiO2-Ag hierarchical shell and their application in catalytic column

Polymer particles with dendrimer@SiO₂–Ag hierarchical shell were prepared, and their application in the catalytic column for the reduction of 4-nitrophenol (4-NP) was also investigated. The PS microspheres with the carboxyl group were used as the supports for the immobilization of dendrimer@SiO₂–Ag shell. The polyamidoamine (PAMAM) dendrimer was grafted on the surface of PS microsphere through repetitive Michael addition reaction of methyl acrylate (MA) and amidation of the obtained esters with a large excess of ethylenediamine (EDA) successively. The silver nanoparticles formed inside the PAMAM shell. Then, the silver nanoparticles, which were used as center of nucleation, were coated with SiO₂ shell through improved Stöber method. Moreover, the more silver nanoparticles were dispersed on the surface of SiO₂ shell. The contents of silver element were measured using inductively coupled plasma (ICP-MS). The obtained PS@PAMAM@SiO₂–Ag nanoparticles were packed in stainless steel column, which has been used effectively for the catalytic reduction of 4-NP. Under column pressures, the rigid SiO₂ shell plays a better role in immobilization of silver nanoparticles than the soft PAMAM shell. This technique for packing catalytic nanoparticles in column improves the efficiency of application with metal catalysts as well as reduces the tedious separation processes in catalytic reaction.     

Morphological change of gold-dendrimer nanocomposites by laser irradiation

Gold-dendrimer nanocomposites are prepared in aqueous solutions in the presence of poly(amidoamine)dendrimers (PAMAM) (generation 3 and 5) or poly(propyleneimine)dendrimers (PPI) (generation 3 and 4) by wet chemical NaBH(4) method. Thus prepared gold-dendrimer nanocomposites are irradiated by laser at 532 nm. UV-vis absorption spectroscopy and transmission electron microscopy reveal that the gold nanoparticles grow with the laser irradiation time as well as the fluence of the laser; in particular, the gold nanoparticles prepared at lower concentrations of PAMAM dendrimer as well as lower generations of PAMAM grow significantly. On the other hand, in the case of PPI dendrimers, the gold nanoparticles hardly grow by irradiation. In addition, dynamic light-scattering measurements show that the laser irradiation markedly promotes the association of the gold-PAMAM G3 dendrimer nanocomposites compared to that of the gold-PAMAM G5 dendrimer nanocomposites, while the sizes of association for the gold-PPI G3, G4 dendrimer nanocomposites hardly change by laser irradiation.     

A layer-by-layer assembly label-free electrochemical immunosensor for the detection of microcystin-LR based on CHIT/PAMAM dendrimer/silver nanocubes

Utilising the affinity and high combination ability between silver nanocubes and amino group (–NH₂), a novel electrochemical immunosensor was constructed for the ultrasensitive detection of microcystin-LR (MC-LR) based on G4-polyamidoamine (PAMAM) dendrimer and Ag nanocubes as immobilised substrate of anti-MC-LR. G4-PAMAM dendrimers were covalently bound on the chitosan (CHIT) – modified electrode by glutaraldehyde (GA), providing abundant amino groups to absorb much more Ag nanocubes comparing without using PAMAM. Subsequently, antibodies of MC-LR were immobilised with highly dense through Ag-NH₂. K₃Fe(CN)₆/K₄Fe(CN)₆ was used as electroactive redox probe. Ag nanocubes/PAMAM can enhance the antibody loading amount, which would bind more MC-LR and hinder the electron transfer of K₃Fe(CN)₆/K₄Fe(CN)₆. Differential pulse voltammetry (DPV) was employed to evaluate the analytical performance of the fabricated signal-off immunosensor. The response current had negative correlation with the concentration of MC-LR. The linear range covered was from 0.05 ng/mL to 25 μg/mL with detection limit (DL) of 0.017 ng/mL at 3σ. The proposed approach showed high specificity for the detection of MC-LR, with acceptable reproducibility, stability and reliability. Compared with the enzyme-linked immunoassay (ELISA) method by analyzing real water samples from Dian Lake, this immunosensor revealed acceptable accuracy with a relative error of 12.7%, indicating a potential alternative method for MC-LR detection in water sample.     

Synthesis of P(MBA-co-MAA) microsphere-grafted PAMAM dendrimers and their application as supporters for gold nanoparticles

Poly(N,N′-methylenebisacrylamide-co-acrylic acid) microsphere-supported polyamidoamine (PAMAM) dendrimers up to third generation (G) were grown onto the surface as well as the gel-layer of P(MBA-co-MAA) microspheres by a divergent method. The P(MBA-co-MAA) supported PAMAM dendrimers were used as heterogeneous stabilizers for the gold nanoparticles by an in situ reduction of HAuCl₄ via the efficient coordination interaction between the amino groups of the supported PAMAM dendrimers and the gold atoms. The effects of the generations of the P(MBA-co-MAA) supported PAMAM dendrimer on the loadings and the catalytic activity of the heterogeneous Au nanoparticles were systematically investigated with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction.     

Self‐assembly of Functionalized Gold Nanoparticles with Rigid and Flexible Multifunctional Linkers

The interparticle spacing of carboxyl functionalized gold nanoparticles (Au‐COOH) were mediated by rigid crosslinkers, octa(3‐aminopropyl)octasilsesquioxane (POSS‐NH₃ ⁺) and poly(amidoamine) dendrimer terminated with hydroxyl groups (PAMAM‐OH), and a flexible polymeric linker, poly(hexanul viologen) (6‐VP). Regular interparticle spacing was achieved by utilizing POSS‐NH₃ ⁺ and PAMAM‐OH dendrimer as cross linkers, whereas size growth of Au‐COOH was observed featuring no interparticle spacing by utilizing 6‐VP as the crosslinker.     

Structural analysis of poly(amidoamine) dendrimer immobilized in crosslinked poly(ethylene glycol)

Polymeric membranes comprised of poly(amidoamine) (PAMAM) dendrimer immobilized in a poly(ethylene glycol) (PEG) network exhibit an excellent CO₂ separation selectivity over H₂. The CO₂ permeability increases with PAMAM dendrimer concentration in the polymeric membrane and becomes 500 times greater than H₂ permeability when the dendrimer content was 50 wt % at ambient conditions (5 kPa of CO₂ partial pressure). However, the detailed morphology of the membrane has not been discussed. The immiscibility of PAMAM dendrimer and PEG matrix results in phase separation, which takes place in a couple of microns scale. Especially, laser scanning confocal microscope captures a 3D morphology of the polymeric blend. The obtained 3D reconstructions demonstrate a bicontinuous structure of PAMAM dendrimer‐rich and PEG‐rich phases, which indicates the presence of PAMAM dendrimer channel penetrating the polymeric membrane, and CO₂ will preferentially pass through the dendrimer channel. In addition, Fourier transform of the 3D reconstructions indicates the presence of a periodic structure. An average size of the dendrimer domain calculated is 2–4 μm in proportion to PAMAM dendrimer concentration. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

磁性Fe_3O_4@PS@PAMAM-Ag复合催化粒子的制备及其可再生催化性能(英文)

采用聚苯乙烯(PS)包裹Fe3O4磁性纳米粒子,制得Fe3O4@PS复合微球,以此作为磁性载体,通过微球表面的羧基将聚酰胺-胺类树形大分子(PAMAM)连接到磁性载体上,然后使Ag纳米粒子镶嵌在树形分子层中,制得可再生的金属复合催化粒子Fe3O4@PS@PAMAM-Ag.并采用红外光谱、扫描电镜、电感耦合等离子体质谱(ICP-MS)和X射线光电子能谱等方法对复合催化粒子进行了表征,结果表明,树形分子可以较好地分散和稳定金属Ag纳米粒子,所制复合催化粒子表面Ag含量为1.64%,具有较高的催化还原对硝基苯酚的活性.同时,利用外加磁场可以方便快捷地从反应体系中分离出来,继续用于下一次反应中,复合催化粒子循环使用6次后,仍保持完全的催化性能.     

Dependence of Property of Silver Nanoparticles within Dendrimer-template on Molar Ratios of Ag+ to PAMAM Dendrimers

G5.0‐OH PAMAM dendrimers were used to prepare fluorescent silver clusters with weaker ultraviolet irradiation reduction method, in which the molar ratio of Ag⁺ to PAMAM dendrimers was the key factor to determine the geometry and properties of silver nanoparticles. The results showed that because of G5.0‐OH PAMAM dendrimers as strong encapsulatores, when the molar ratios of Ag⁺ to PAMAM dendrimers was smaller than 5, the obtained Ag_n clusters (n<5) had line structures and "molecular‐like" properties, which were highly fluorescent and quite stable in aqueous solution. Whereas when the molar ratios were between 5 and 8, the obtained Ag_n clusters were 2D structures and their fluorescence was weaker. When the molar ratio was larger than 8, the structure of silver nanoparticles was 3D and no fluorescence was observed from the obtained silver nanoparticles.