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1.
建立一种无模板的恒电位电聚合方法,可在室温下制备对甲基苯磺酸(p-TSA)掺杂的多级树状纳米结构聚苯胺(PANI).根据电聚合曲线分析了PANI的聚合机理.扫描电镜(SEM)、透射电镜(TEM)观察表明制备的PANI具有均匀的多级树状纳米结构.紫外可见吸收光谱(UV-Vis)和红外光谱(FTIR)则显示所制备的PANI为掺杂态.该电沉积方法具有简便、易操作的特点,还可应用于其他纳米结构导电聚合物的可控制备.  相似文献   

2.
Porous hollow spherical and rod-like silica nanoparticles were obtained via a surfactant templating method adopting hydroxyapatite (HAp) nanoparticles as an etchable core material.  相似文献   

3.
Electrochemical study of polyaniline deposited on a titanium surface   总被引:3,自引:0,他引:3  
The electrochemical synthesis of polyaniline on a titanium surface in aqueous sulfuric acid solutions with various concentrations of added aniline has been investigated by cyclic voltammetry. By utilizing a more cathodic potential range (up to −0.6 V) for the cyclization than is usual (up to −0.2 V) on Pt and Au electrodes, the new voltammetric waves have been deconvoluted from the already well-known ones for polyaniline. By simultaneous electrochemical and in situ Raman spectroscopic measurements, the Raman bands of polyaniline electrodeposited on a Ti electrode, were assigned for potentials of −0.15 V and −0.6 V. It was found that the new monitored waves were closely related to the so-called “middle” peaks and appear only when the polyaniline reaches an overoxidized state. Received: 7 August 1997 / Accepted: 4 November 1997  相似文献   

4.
In this work, the role of nanoparticle surface charge in surface-enhanced Raman scattering (SERS) is examined for the common case of measurements made in colloidal solutions of Ag and Au. Average SERS intensities obtained for several analytes (salicylic acid, pyridine, and 2-naphthalenethiol) on Ag and Au colloids are correlated with the pH and zeta potential (zeta) values of the nanoparticle solutions from which they were recorded. The consequence of the electrostatic interaction between the analyte and the metallic nanoparticle is stressed. The zeta potentials of three commonly used colloidal solutions are reported as a function of pH, and a discussion is given on how these influence SERS intensity. Also examined is the importance of nanoparticle aggregation (and colloidal solution collapse) in determining SERS intensities, and how this varies with the pH of the solution. The results show that SERS enhancement is highest at zeta potential values where the colloidal nanoparticle solutions are most stable and where the electrostatic repulsion between the particles and the analyte molecules is minimized. These results suggest some important criteria for consideration in all SERS measurements and also provide important insights into the problem of predicting SERS activities for different molecular systems.  相似文献   

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A simple and versatile method for the synthesis of a wide range of polyaniline (PANI)-based 1D and 2D gold nanostructures of uniform size distribution with high colloidal stability is demonstrated. All the nanostructures were synthesized from oligoaniline-coated gold nanoparticle precursors. The nanostructures include nanowires of various sizes, nanoplates, and flower-like nanoparticles. These nanowires showed a pH-dependent shape transformation. Needle-like aggregates of Au/PANI were formed as the pH of the nanowire solution changed to 2.5. At higher pH (10.2), nanowires converted into spherical nanoparticles. Core-shell particles of Au/PANI composites have been achieved by the reversal of the pH of the nanowire from 10.2 to 2.9. The morphology of the nanostructures was studied by TEM and SEM. FTIR, UV-vis, XRD, and LDI MS were utilized for the characterization of the chemical composition of the nanostructures. A mechanism for the nanowire growth is proposed.  相似文献   

8.
A wide range of biomineralization and templating methods exist for organizing inorganic materials at a wide range of length-scales. Here, we show that crystallographic control of the inorganic nanostructures is possible using synthetic biomolecular templates comprised of anionic DNA and cationic membranes, which self-assemble into a multilamellar structure where a periodic one-dimensional (1D) lattice of parallel DNA chains is confined between stacked two-dimensional (2D) lipid sheets. We have organized Cd2+ ions within the interhelical pores between DNA strands and subsequently reacted them with H2S to form CdS nanorods of controllable widths and crystallographic orientation. The strong electrostatic interactions align the templated CdS (002) polar planes parallel to the negatively charged sugar-phosphate DNA backbone, which indicates that molecular details of the DNA molecule are imprinted onto the inorganic crystal structure. The resultant nanorods have (002) planes tilted by 60 degrees with respect to the rod axis, in contrast to all known II-VI semiconductor nanorods.  相似文献   

9.
We combine X-ray reflectivity and scanning electron microscopy measurements to investigate the mechanisms involved in the growth of vertical arrays of phthalocyanine nanowires directed by templates of Au nanoparticles. The study has been carried out for H(16)CuPc at different substrate temperatures. It is shown that three organic morphologies evolve during the growth: 1D nanostructures on top of the Au nanoparticles, a multilayer film on the substrate and a layer wetting the gold nanoparticles. For substrate temperatures below 100 °C there is a coexisting and competing growth of the three structures, whereas beyond this temperature the 1D growth on the nanoparticles is predominantly favored. The observance of two regimes with the temperature is characterized by two different activation energies. Both the length of the 1D structures and the thickness of the multilayer film can be precisely controlled by the substrate temperature which is of importance for application of vertical organic nanowires as donor/acceptor architecture in organic solar cells.  相似文献   

10.
The kinetics of the electrochemical degradation of polyaniline (PANI) films has been investigated in 0.5 M sulfuric acid solution at different electrode potentials ranging from 0.3 to 1.0 V vs. Ag/AgCl. Two kinds of PANI films were used, one doped with poly(styrene sulfonate) (PSS), and the other—with indigotetrasulfonate (ITS). Within a range of relatively low electrode potential (0.3-0.6 V), the degradation was found to proceed at a first-order rate constant of 4×10−5 to 5×10−5 s−1, corresponding to degradation half-period of 4-5 h. A sharp increase in the degradation rate proceed by extending the electrode potential to higher values, with a maximum rate constant of ≈2.5×10−3 s−1 for PANI-PSS, and ≈1.2×10−3 s−1 for PANI-ITS films, obtained at a higher potential of 0.9-1.0 V. The data obtained are interpreted by different degradation rate for two distinct redox forms of PANI—emeraldine (slow degradation), and pernigraniline (fast degradation).  相似文献   

11.
Amphiphilic block copolymers containing phosphine moieties in the main chain are employed as macromolecular ligands for gold(I). The sequential living anionic copolymerization of isoprene (I) and the phosphaalkene, MesP CPh2 (Mes = 2,4,6-trimethylphenyl) affords the block copolymer [PI]404-b-[MesP-CPh2]32 (1a). The incorporation of gold(I) moieties into this functional copolymer is accomplished by treating 1 with THT.AuCl (THT = tetrahydrothiophene) which affords [PI]404-b-[MesP(AuCl)-CPh2]32 (2a). Remarkably, dissolution of gold-functionalized 2 in n-heptane, a block-selective solvent for isoprene, affords spherical micelles with gold(I)-rich cores. Micelles were examined by transmission electron microscopy (TEM) and dynamic light scattering (DLS). We also prepared two additional copolymers with longer phosphine blocks and shorter PI segments: [PI]222-b-[MesP(AuCl)-CPh2]77 (2b) and [PI]164-b-[MesP(AuCl)-CPh2]85 (2c). When assembled in isoprene-selective solvents, 2b forms wormlike structures and 2c, with the longest phosphine block, forms fascinating micron sized intertwined wormlike structures. This represents a new method to control the shape and size of gold(I) nanostructures.  相似文献   

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The slow voltammetry was taken on the paste electrode consisting of polyaniline powder and Teflon binder which was applied to pyrographite disc electrode. The potential cycle range was +0.6V→ ? 0.2V→+0.8V→+0.6V vs. SCE. It was found that the voltammetry curves are similar for both polyanilines obtained chemically and electrochemically. The difference of the voltammetry curves in various acids might be attributed to some exchange of doping anions in polyaniline. The first redox couple peaks shifted to positive potential direction with increase of pH and it might be associated with the proton addition-elimination reaction. It was shown that polyaniline prepared from very dilute or concentrated acid solution was electrochemically inactive.  相似文献   

14.
The installation of large scale colloidal nanoparticle thin films is of great interest in sensor technology or data storage. Often, such devices are operated at elevated temperatures. In the present study, we investigate the effect of heat treatment on the structure of colloidal thin films of polystyrene (PS) nanoparticles in situ by using the combination of grazing incidence small-angle X-ray scattering (GISAXS) and optical ellipsometry. In addition, the samples are investigated with optical microscopy, atomic force microscopy (AFM), and field emission scanning electron microscopy (FESEM). To install large scale coatings on silicon wafers, spin-coating of colloidal pure PS nanoparticles and carboxylated PS nanoparticles is used. Our results indicate that thermal annealing in the vicinity of the glass transition temperature T(g) of pure PS leads to a rapid loss in the ordering of the nanoparticles in spin-coated films. For carboxylated particles, this loss of order is shifted to a higher temperature, which can be useful for applications at elevated temperatures. Our model assumes a softening of the boundaries between the individual colloidal spheres, leading to strong changes in the nanostructure morphology. While the nanostructure changes drastically, the macroscopic morphology remains unaffected by annealing near T(g).  相似文献   

15.
The solution-phase synthesis by chemical transformation from reactive templates has proved to be very effective in morphology-controlled synthesis of inorganic nanostructures. This review paper summarizes the recent progress in solution-phase synthesis of one-dimensional and hollow inorganic nanostructures via reactive templates, focusing on the approaches developed in our lab. The formation mechanisms based on reactive templates are discussed in depth to show the general concepts for the preparation proces...  相似文献   

16.
Polyaniline nanoparticles were prepared on a highly oriented pyrolytic graphite (HOPG) surface from dilute polyaniline acidic solution (1 mM aniline+1 M HClO4) using a pulsed potentiostatic method. Electrochemistry, Fourier transform infrared external reflection spectroscopy (FT-IR-ERS), X-ray photoelectron spectroscopy (XPS) and tapping-mode atomic force microscopy (TMAFM) were used to characterize the composition and structure of the polyaniline nanoparticles. FT-IR-ERS and XPS results revealed that the polyaniline was in its emeraldine form. TMAFM measurement showed that the electropolymerized polyaniline nanoparticles dispersed on the HOPG surface with a coverage of about 1010 cm−2. These nanoparticles were disk-shaped having a height of 10–30 Å and an apparent diameter varying from 200 to 600 Å. The particle dimensions increased with the electropolymerization charge (Q) over the interval from 5.7 to 19.3 μC cm−2.  相似文献   

17.
Protonation of polyaniline base with lightly sulfonated polystyrene in polar solvents such as dimethyl sulfoxide and N-methyl-2-pyrrolidone was investigated by UV-Vis absorption spectra. As the molar ratio of sulfonated polystyrene/polyaniline increases, the conversion from polyaniline base form to salt form is observed owing to increased protonation. The isosbestic point clearly shows that quinoid unit and semiquinoid unit are in equilibrium. They are functions of the sulfonic acid concentration and solvent media.  相似文献   

18.
In this study different membranes were produced, aiming to evaluate their use in electrodialysis. These membranes were produced using conventional polymer (high-impact polystyrene) and polyaniline. The membrane characterization was done by FTIR spectroscopy, scanning electron microscopy (SEM), and thermogravimetry (TGA). The studies of the zinc and proton extraction ionic transport through the membranes were evaluated using a three-compartment cell. The results obtained using the produced membranes were compared to the results obtained with the commercial membrane Nafion 450. It was found that a synthesized membrane can be used to recover zinc in acid media. In addition, a preliminary computational essay about the structures of PAni and CSA is presented.  相似文献   

19.
Using uncharged or negatively charged L-lysine-based organogelators as templates, the nanostructures of TiO2 are controllable.  相似文献   

20.
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