高分子模板法合成特殊形态的氧化锌纳米结构材料

利用超分子模板法的形态花样复制制备具有复杂形态的无机超细材料已引起越来越多人的兴趣[1,2].模板与无机物之间的协同作用可制得有内部通道的新型中空分子筛[3,4],但无机材料合成在纳米尺度及亚微米尺度上的形态花样仍落后于生物矿化.生物矿化的独特之处在于可以通过自组合的有机集体或超分子模板通过材料复制而转变为有序的无机结构(如骨,壳,齿),这一合成原理也引导了我们利用高分子模板合成具有复杂形态的无机材料. 作者利用不同分子量的非离子型聚合物PEG作为大分子表面活性剂,在特定的胶束浓度范围和介质体系中形成超分子模板,以之作为"微反应器”并利用PEG与无机物之间的协同作用,控制模板水核中的水解反应;在特定的试剂浓度与比例、温度等条件下,除制备了具有球形、针/棒状纳米氧化锌粒子外,还制得了均匀分散的六角形、片状、螺旋棒状的氧化锌纳米、亚微米材料.     

硫化锌与硫化锌/氧化锌异质结纳米线的化学气相沉积法制备与表征

介绍一种利用石墨还原快速制备大量硫化锌纳米线的方法,并分别合成了超晶格型、双轴型、核/壳型的硫化锌/氧化锌异质结纳米线。所合成的硫化锌纳米线存在六方纤锌矿和立方闪锌矿两种晶型,纳米线长度达几十微米,直径在20-50 nm,直径均匀且产量很高。在具有双轴型的硫化锌/氧化锌异质结中,首次发现具有超结构特征的氧化锌。HRTEM分析表明,硫化锌/氧化锌超晶格异质结界面为ZB-ZnS(111)∥ZnO(0001),而核/壳型异质结界面为W-ZnS(0001)∥ZnO(0001),这三个晶面分别为各自晶体的极性面,即所合成的硫化锌/氧化锌异质结中极性面相互平行。对ZnS 和ZnS/ZnO 异质结的生长机制进行了探讨,并对硫化锌纳米线与硫化锌/氧化锌异质结的光学性质进行了分析。     

软外延生长法构筑纳米粒子超晶格材料

由纳米粒子自下而上自组装而成、高度有序的纳米粒子超晶格材料是近年来兴起的一类新型材料.本文主要概述了软外延生长法构筑纳米粒子超晶格材料的概念及组装策略,结合近几年本课题组的相关研究工作,主要介绍了几种不同的基底材料,以及通过调控基底与纳米粒子之间的相互作用来构建纳米粒子超晶格材料.具体包括以纳米粒子超晶格、有机分子笼晶体以及超分子组装体等作为基底诱导纳米粒子软外延生长.通过软外延生长法可实现对纳米粒子超晶格维度(包括一维、二维以及三维)的有效调控.同时,阐明了纳米粒子与基底材料的弱键相互作用机制,该机制也成为构筑无机纳米粒子/有机分子有序组装体重要的物理化学基础.     

DNA步行器调控的纳米粒子超晶格

作为一种精巧的DNA纳米机器, DNA步行器因其优异的可设计性及可编程性在众多研究领域中展示出强大的应用价值. 本工作通过将基于催化发夹组装的双足DNA步行器与DNA功能化的金纳米粒子(即球形核酸)组装相结合, 开发了一种具有时间依赖性的DNA步行器驱动球形核酸恒温有序组装的策略. 以单组分球形核酸组装体系为例, DNA步行器通过发夹催化组装反应驱动在球形核酸表面上随机行走并逐渐产生带有活性粘性末端的DNA杂交结构, 促使球形核酸表面粘性末端间的“键合”速率与其组装速率在时间尺度上保持同步, 从而得到面心立方(FCC)晶型的超晶格结构. 基于类似原理, 作者还构建了一种DNA步行器驱动的双组分球形核酸组装体系并以此得到氯化铯(CsCl)晶型的超晶格结构.     

弱酸介质中类球形谷氨酸/镁铝层状双氢氧化物的制备

在弱酸性介质中,采用阴离子交换法合成了类球形的谷氨酸(Glu)/镁铝层状双氢氧化物(MgAl-LDH)复合物,研究了介质pH值对所得Glu/LDH纳米复合物性质和形貌的影响。结果表明,与碱性介质中阴离子交换法得到的不规则六角形粒子相比,该法制备的纳米粒子呈类球形,且粒径较小,最佳pH值为5.0,探讨了可能的反应机理。     

ZnO/Ag复合纳米粒子的制备与表征

以乙酸锌为前驱物,乙醇为溶剂,油酸钠为表面修饰剂,采用溶液化学法,在乙醇体系中制得纳米Zn O。然后缓慢加入一定量的硝酸银乙醇溶液,在乙醇的还原作用下将Ag+还原为Ag纳米粒子,制得Zn O/Ag复合纳米粒子。通过紫外-可见吸收光谱(UV-Vis)、荧光光谱(FL)、透射电子显微镜(TEM)和X射线衍射(XRD)等方法对所制备的氧化锌-银复合纳米粒子样品进行表征。结果表明,所合成的Zn O/Ag复合纳米粒子为球形,尺寸为20-30nm且粒径分布较窄。Ag纳米粒子附着于Zn O纳米粒子表面,并起到良好的表面修饰作用。对制备Zn O/Ag复合纳米粒子的机理进行了初步探究。     

聚乙烯亚胺修饰BaGdF_5纳米粒子的制备及CT/MR双模成像性能

通过微波辅助的溶剂热法制备了聚乙烯亚胺修饰BaGdF_5纳米粒子,并对其进行了表征、毒性评估、计算机X射线断层扫描(CT)成像及磁共振(MR)成像分析.透射电子显微镜(TEM)观测结果表明,该纳米粒子呈球形,表面光滑,分布均匀,粒径约30 nm.MTT结果表明,该纳米粒子具有较低的细胞毒性;小鼠各器官的组织病理学结果表明,该纳米粒子具有较低的体内毒性;体外成像结果表明,该纳米粒子具有较好的CT成像及T1加权的MR成像能力;小鼠体内成像结果表明,该纳米粒子具有应用于肝脏双模态成像的潜力.     

两亲性三嵌段共聚物PHB-PEG-PHB的合成及其纳米粒子的制备与表征

基于聚(β-丁内酯)(PHB)和聚乙二醇(PEG)的两亲性三嵌段共聚物聚(β-丁内酯)-聚乙二醇-聚(β-丁内酯)(PHB-PEG-PHB)可在聚乙二醇钾盐大分子引发剂的作用下、以四氢呋喃为溶剂,通过β-丁内酯(BL)的阴离子开环聚合进行制备,调节BL与聚乙二醇钾盐的配比,可制备分子量不同的共聚物.产物可通过1H-NMR、13C-NMR、FTIR、DSC、GPC等测试进行表征,DSC结果表明无定形的PHB阻碍了PEG的结晶,且随着PHB链段长度的增加,阻碍作用更加明显.PHB-PEG-PHB可在水中通过沉淀/溶剂蒸发技术进行自组装形成具有核壳结构的纳米粒子,并通过SEM、DLS手段对其表征,发现粒子尺寸在纳米级,形态为球形或方形.聚合物的初始浓度对纳米粒子的形态和尺寸有明显影响,随着聚合物初始浓度的降低,纳米粒子的尺寸降低.     

梨形核壳结构氧化锌/银亚微米球的制备、表征及光学性能

利用亚锡离子还原银离子生成的金属银沉积在合成的梨形氧化锌表面作为晶种,进一步生长银纳米粒子,制备了梨形的、核壳结构的、单分散的氧化锌/银亚微米球。利用X射线衍射、透射电镜、能量色散X射线谱、紫外可见吸收谱及光致发光谱对所制备样品的形貌、微观结构、组成和光学性能进行了表征。结果表明:(1)样品是由梨形亚微米氧化锌核和银纳米颗粒壳组成;(2)在氧化锌表面的银纳米粒子作为光激发产生的电子捕获剂提高了光产生的载流子的分离效率,在能量没有改变的情况下减少了紫外发射光的强度,淬灭了可见发射光。     

Mn0.6 Zn0.4 Fe2 O4 磁性亚微球的可控合成及磁性能

采用溶剂热法制备了单分散Mn0.6Zn0.4Fe2O4磁性亚微米球, 研究了反应工艺参数对磁性亚微米球结构形貌、 直径和静磁性能的影响规律. 研究发现, 随着反应时间的延长, 体系中的金属离子首先水解沉淀, 形成羟基氧化铁及Mn, Zn氢氧化物, 然后脱水转化为Mn0.6Zn0.4Fe2O4球形纳米粒子, 这些纳米粒子发生团聚, 形成结构疏松、 大小不均匀的亚微米粒子, 最后通过Ostwald熟化过程, 形成致密的单分散亚微米球. 降低反应溶液的pH值、 增加乙二醇或聚乙二醇的用量, 均会使亚微球的直径增大, 并可在150~500 nm范围内调控微球的粒径; 但组成磁性亚微球的纳米粒子的粒径逐渐减小, 产物的饱和磁化强度增大, 矫顽力和剩磁减小.     

葡聚糖双亲性衍生物修饰PLA亚微粒子的制备及其表面多重生物因子功能化

以胆固醇半琥珀酸酰氯对NaIO4氧化的醛化葡聚糖进行疏水改性,制备了醛基化双亲性葡聚糖衍生物Chol-Dex-CHO;利用醛基与己二酰肼酰腙化反应,实现葡聚糖主链的氨基化;生物素经二环已基碳二亚胺活化后与双亲性葡聚糖衍生物主链上的氨基偶联,形成生物素化(3%)双亲性葡聚糖(Chol-Dex-Biotin).将聚乳酸(PLA)与Chol-Dex-Biotin溶液共透析可形成亚微粒子,双亲性多糖可通过疏水基团锚定于PLA亚微粒子表面,透射电子显微镜与原子力显微镜测试观察到清晰的球形核壳结构,激光粒度仪测定亚微粒子粒径与粒径分布表明调节Chol-Dex-Biotin与PLA的配比可以控制亚微粒子的粒径(150~200 nm),X-射线光电子能谱证明亚微粒表面存在Chol-Dex-Biotin.在此基础上,以FITC标记的转铁蛋白(Tf-FITC)和生物素化兔IgG为模型生物功能因子,分别通过共价偶联及生物素-亲合素物理结合两种机理对葡聚糖包覆的PLA纳米微粒表面进行多重生物因子功能化修饰,得到表面Tf和IgG双重修饰的PLA亚微粒子(Tf-PLA-IgG submicron particles).亚微粒子表面Tf和兔IgG的结合分别通过荧光显微镜观测和抗IgG-辣根过氧化氢酶(IgG-HRP)显色反应验证.     

Effect of aging time and Al substitution on the morphology of aluminous goethite

Highly ordered submicron spherical Fe-MCM-48 was successfully synthesized by a mixed surfactant method using cheap water glass as silica source. The gyroid like structure of MCM-48 was captured by a TEM image for the first time, and it was corresponded well to the previous simulated gyroid model. A tentative mechanism of homogenization cooperative process involving the Helmholtz double electrical layer was purposed. After the loading of metal Ag, the resulting Ag/Fe-MCM-48 catalyst showed good catalytic performance in the catalytic combustion of benzene.     

Direct synthesis of mesoporous titania particles having a crystalline wall

In this study, we demonstrate a novel method for preparing crystallized mesoporous titania by using a low-temperature synthesis technique in the presence of cationic surfactant. XRD patterns showed that the titania particles obtained had both hexagonal structure and a wall with anatase crystalline structure. Transmission electron microscopy (TEM) observation and corresponding electron diffraction pattern confirmed that the calcined particles are crystallized mesoporous titania.     

Solventless synthesis of copper sulfide nanorods by thermolysis of a single source thiolate-derived precursor

Organic monolayer protected Cu2S nanorods, 4 nm in diameter and 12 nm long, were synthesized using a novel solventless synthetic approach. Thermolytic degradation of a copper thiolate precursor at temperatures ranging from 140 to 200 degrees C produces Cu2S nanorods. Higher temperatures promote isotropic growth of spherical nanocrystals. X-ray diffraction and high-resolution TEM reveal that the nanorods exhibit a hexagonal Cu2S crystal structure, which in the bulk is ferroelectric. The appropriate reaction conditions produce nanorods that are size and shape monodisperse and organize into smectic superlattices. The extent of superlattice ordering and the appearance of extended strands of nanorods provide evidence for strong dipole-dipole coupling between Cu2S nanorods.     

丙烯酰胺辅助溶剂热技术调控硫化镍的物相及形貌

以硝酸镍和硫脲为原料、乙二醇为溶剂、丙烯酰胺作为表面活性剂,采用溶剂热技术制备了立方相NiS₂,六方相α-NiS,和菱形β-NiS空心球,并用XRD及TEM对产物进行了表征。结果显示：丙烯酰胺能够有效调控硫化镍的物相组成和形貌结构。最后利用异相晶化及卷曲机理(rolling-up mechanism)解释了β-NiS空心微球的形成过程。     

Preparation,Characterization, and Evaluation of the Anticorrosion Performance of Submicron/Nanocarbon from Jute Sticks

Jute stick, one of the most commonly and abundantly available agricultural waste product, was converted to a value-added submicron/nano jute carbon by using pyrolysis and high-energy ball milling techniques. The submicron/nano jute carbon was characterized using FE-SEM, TEM, EDS, XRD, XPS and Raman spectroscopy. The anticorrosive performance of the submicron/nano jute carbon was investigated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and salt spray techniques, on mild steel plates coated with a mixture of epoxy resin and the submicron/nano jute carbon. The electrochemical impedance of the steel coated with the composite coating was two orders of magnitudes higher than that of the specimen coated with neat epoxy. Consequently, the corrosion rate of specimens coated with composite coating was 13–20 times higher than that of steel coated with neat epoxy coating. The salt spray results also indicate an improvement in the corrosion resistance performance of the composite coating compared to the neat epoxy. The uniform distribution of the submicron/nano jute carbon particles in the epoxy resin improved the denseness of the composite coating by acting as a barrier against the diffusion of chloride, moisture, and oxygen, thus, improving the corrosion resistance of the developed coating.     

Electric field-induced self-assembly of micro- and nanoparticles of various shapes at two-fluid interfaces

Particle lithography which explores the capability of particles to self-assemble offers an attractive means to manufacture nanostructured materials. Although traditional techniques typically lead to the formation of dense crystals, adjustable non-close-packed crystals are crucial in a number of applications. We have recently proposed a novel method to assemble spherical micro- and nanoparticles into monolayers. The technique consists of trapping particles at a liquid-fluid interface and applying an electric field normal to the interface. Particles rearrange themselves under the influence of interfacial and electrostatic forces to form 2-D hexagonal arrays of long-range order and whose lattice constant depends on the electric field strength and frequency. Furthermore, the existence of an electric field-induced capillary force makes the technique applicable to submicron and nanosized particles. Although spherical particles are often used, non-spherical particles can be beneficial in practice. Here, we review the method, discuss its applicability to particles of various shapes, and present results for particles self-assembly on air-liquid and liquid-liquid interfaces. In the case of non-spherical particles, the self-assembly process, while still taking place, is more complex as particles experience a torque which causes them to rotate relative to one another. This leads to a final arrangement displaying either a dominant orientation or no well-defined orientation. We also discuss the possibility of dislodging the particles from the interface by applying a strong electric field such that the Weber number is of order 1 or larger, a phenomenon which can be utilized to clean particles from liquid-fluid surfaces.     

Preparation of crystalline gold nanoparticles at the surface of mixed phosphatidylcholine-ionic surfactant vesicles

The formation of gold nanoparticles and the crystal growth at the surface of mixed phosphatidylcholine (PC)-ionic surfactant vesicles was investigated. The PC-bilayer surface was negatively charged by incorporating sodium dodecyl sulfate (SDS) and positively charged by adding hexadecyltrimethylammonium chloride (CTAB). The mass ratio phosphatidylcholine:surfactant was fixed in both cases at 1:1. The gold nanoparticle formation was studied by using transmission electron microscopy (TEM) combined with dynamic light scattering (DLS) and UV-vis absorption spectroscopy. TEM micrographs confirm that the particle formation occurs on the vesicle surface. However, the reduction process depends on the ionic surfactant incorporated into the vesicles, the vesicle size distribution, as well as the temperature used for the reduction process. Thereby, it becomes possible to control the crystal growth of the individual spherical gold nanoparticles in a characteristic way. Red colored colloidal dispersions consisting of monodisperse spherical nanoparticles with an average particle size between 2 and 8 nm (determined by dynamic light scattering) can be obtained by using a monodisperse SDS-modified vesicle phase. When the temperature is increased to 45 degrees C, a crystallization in rod-like or triangular structures is observed. In the CTAB-based template phase in general larger gold particles of about 35 nm are formed. In similarity to the anionic vesicles a temperature increase leads to the crystallization in triangular structures.     

巯丙基功能化介孔纳米二氧化硅的合成

用三种不同的方法将巯基丙基三甲氧基硅烷(MPTMS)引入二氧化硅网络中, 合成了粒径为50-200 nm的巯丙基功能化的介孔纳米二氧化硅, 并利用透射电子显微镜, 热重分析等手段对其形貌与性能进行了表征. 在巯丙基官能团的作用下介孔纳米二氧化硅的形貌发生了重大改变, 由非常规则的六角形变为纳米棒. 控制反应时间可以调节介孔纳米二氧化硅的粒径大小, 用三乙醇胺代替氢氧化钠可以合成直径在100 nm以下的功能化介孔二氧化硅粒子. 为了保护巯基官能团, 选用了酸醇提取法去除模板. 另外, 对介孔二氧化硅粒子的形成机制也进行了探讨.     

Synthesis of hollow spherical silica with MCM-41 mesoporous structure

Hollow spherical mesoporous silica was synthesized by using sodium silicate as a precursor and a low concentration of cetyltrimethylammonium bromide (CTAB) (0.154 mol dm^–3). The resulting hollow spherical particles were characterized with scanning electron microcopy (SEM), small-angle X-ray diffraction (SXRD), transmission electron microscopy (TEM), and N₂ gas adsorption and desorption techniques. The results showed that regular spherical mesoporous silica could be obtained only if the molar ratio of propanol to CTAB was in the range of approximately 8:1–9:1. The spherical particles were hollow (inside), and the shell consisted of smaller particles with a pore structure of hexagonal symmetry. With an increase of the molar ratio of propanol to CTAB, the distance (a value) between centers of two adjacent pores increased, and the pore structure of mesoporous silica became less ordered. N₂ adsorption–desorption curves revealed type IV isotherms and H1 hysteresis loops; with an increase of the molar ratio of propanol to CTAB, the pore size with Barrett–Joyner–Halenda (BJH) diameter of the most probable distribution decreased, but the half peak width of the pore size distribution peak increased