Densely packed organic nanocrystals ultrathin film using a liquid–liquid interface

We report a fabrication of densely packed polydiacetylene nanocrystal film using a liquid–liquid interface. Polydiacetylene (pDCHD) nanocrystals was dispersed into water solution by reprecipitation method from a good solvent. Then, hexane was added to the water dispersion to create the liquid–liquid interface. pDCHD nanocrystals were assembled at the interface, when ethanol was added to the pDCHD water dispersion–hexane solution. The assembled film was transferred onto a solid substrate and the film morphology was observed by scanning electron microscope (SEM). With addition of 10 vol% of ethanol to 2.5 mM of pDCHD water dispersion–hexane solution, a densely packed pDCHD film is fabricated. Optical and electrical properties of the pDCHD film are discussed by UV–vis spectroscopy and current–voltage measurement.     

Synthesis,characterization and spectroscopic studies of CdS/polyaniline core/shell nanocomposite

In this work, CdS/polyaniline (PANI) nanocomposite was synthesized by a novel method. Transmission electron microscope (TEM) images showed that the CdS/PANI nanocomposite had a core/shell structure. The crystal structure was studied using X-ray diffraction (XRD) and the obtained results showed that CdS had cubic structure. Fourier transform infrared (FTIR) spectroscopic measurements confirmed the formation of PANI at the surface of CdS nanoparticle. The prepared samples were further characterized using UV–visible (UV–vis) and fluorescence spectroscopy.     

Synthesis and optical properties of yttria-doped ZrO2 nanopowders

Yttria-doped zirconia (YDZ) nanopowders were synthesized via a solvothermal route using ethanol as solvent. Evolution of crystal phases for different amount of yttria-doped samples were studied by X-ray diffraction (XRD). Morphology and component of the as-synthesized cubic YDZ were characterized by scanning electron microscopy (SEM) and energy dispersion spectrum (EDS). Defects of the sample were detected using ultraviolet–vis (UV–vis) absorption spectrum and photoluminescence (PL) spectrum. The results indicated that cubic structured nanocrystals can be obtained through doping 4 mol% Y₂O₃ into ZrO₂ lattice. The particles had sphere morphology with an average crystal size of 10 nm and agglomerated into bigger spheres with a diameter of about 120 nm. Mechanism of the agglomeration was also discussed. UV spectra showed two absorption peaks, red shift for both of the adsorption edges was observed. PL spectra with excitation wavelength of 260 and 420 nm revealed six fluorescence peaks which were regarded as various energy levels in the band gap and as the evidence of existence of oxygen vacancies in the as-synthesized sample.     

Preparation and characterization of fly ashes and polyaniline core/shell microspheres

To modify the surface of fly ashes (FAs), conductive polyaniline (PANI) layer were chemically grafted on the surface of the self-assembled monolayer (SAM) coated FA particles, resulting in SAM-FAs/PANI composites. The surface functionalization of FAs with amino groups was found to play an important role in the formation of the well-defined core/shell structure. The composites possess good conductivity, average specific capacitance and good magnetic properties at room temperature. Moreover, the conductivity stability and thermal stability of SAM-FAs/PANI composites were clearly improved. The resulting composites were characterized by using wide-angle X-ray diffraction analysis, Fourier transform IR spectroscopy, UV–vis spectroscopy, thermogravimetric analysis, and scanning electron microscopy.     

First preparation of optical quality films of nano/micro hollow spheres of polymers of aniline

In the present study, an experimental procedure used to prepare high-quality, transparent, uniform thin film of a new nano/micro material, a new type of polymer of aniline, is described. The method was used to prepare, for the first time, a solid-state thin film of nano/micro material for various types of studies, such as ultraviolet and visible spectroscopy (UV–vis), scanning electron microscopy (SEM) and electrochemistry. The UV–vis spectra showed that the as-prepared solid thin film of the nano/micro material was apparently not protonated when it was formed in an acidic solution of pH 3.0 since no change in the UV–vis spectrum was observed when it was treated with a deprotonating solution of 1.0 mol dm⁻³ of ammonium hydroxide. To our surprise, it was found that the UV–vis spectrum of a nano/micro material deposited on a glass slide was completely different from its solution UV–vis spectrum when the film was dissolved in NMP (N-methyl-2-pyrrolidinone). The SEM studies showed that the thin film consists of rod-like nanostructures as well as nano/micro spheres. The electrochemical studies showed that the thin film of the nano/micro material deposited on ITO surface presented only one redox process in the potential interval of −0.20 and +0.80 V (versus SCE) in the presence of 1.0 mol dm⁻³ hydrochloric acid.     

Soluble polydiacetylenes: molecular properties and solid state organization

The solution properties of a novel soluble polydiacetylene, poly[1,6-bis(3,6-dihexadecyl-N-carbazolyl)-2,4-hexadiyne] (polyDCHD-HS), have been investigated by use of spectroscopic (UV–VIS absorption, fluorescence and FT-Raman) and light scattering techniques in benzene and toluene. The unique spectroscopic and molecular properties of these solutions are reported and discussed in relation to the particular interactions of the polymer substituents with aromatic solvents. The introduction of the long alkyl-substituents on the carbazolyl side groups not only improves the processability relative to the parent unsubstituted polymer but also suppresses the chromic effects observed in other soluble polydiacetylenes. The side groups are also responsible for the peculiar supramolecular organization observed in the powder phase of the red form.     

Preparation of poly(N-vinylcarbazole) (PVK) nanoparticles by emulsion polymerization and PVK hollow particles

PVK nanoparticles were obtained by oil-in-water emulsion polymerization of N-vinylcarbazole (VCz). VCz is a white crystalline material with a melting point of 65 °C, which is an unsuitable monomer for conventional emulsion polymerization because of its crystallinity. However, we could successfully synthesize PVK nanoparticles by emulsion polymerization from VCz solution with organic solvent. And then, we found that the concentration of VCz influenced the particle size. PVK hollow particles were also obtained by etching of PMMA core from PMMA/PVK core–shell particles, and the size of a hollow particle was enlarged by two times compared with a core–shell particle due to the swelling process. PVK nanoparticles were probed by UV–vis absorption and fluorescence spectrometers, and hollow particles were characterized by FT-IR spectra. Both of them were confirmed by TEM, and the light-scattering instrument.     

Substituted oligoanilines: synthesis and characterization

Substituted trimeric oligoanilines were synthesized by palladium-catalyzed aromatic amination, followed by hydrogenolysis or transamination and thermolysis. The effects of substituent groups on the electronic and electrochemical properties were characterized by cyclic voltammetry and UV–vis spectroscopy. Electron-donating groups decreased the oxidation potential and had little effect on the UV–vis absorption, while electron-withdrawing groups increased the oxidation potential and the UV–vis absorption wavelengths. Electrical conductivities were in the range from 10⁻⁵ to 10⁻³ S/cm when the oligoanilines were doped with iodine.     

“One-pot” synthesis,characterization, and NH3 sensing of Pd/PEDOT:PSS nanocomposite

In this letter, we report a novel route to prepare stable Pd/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (Pd/PEDOT:PSS) colloid. With addition of PSS, the Pd/PEDOT:PSS aqueous dispersion was formed by simultaneous oxidation–reduction reaction between Pd(NO₃)₂ and ethylenedioxythiophene (EDOT) at room temperature. The morphologies of the Pd/PEDOT and Pd/PEDOT:PSS nanocomposites were characterized by transmission electron microscope. The Pd nanoparticles in the composites were identified with X-ray powder diffraction and UV/vis/NIR spectrum. The chemical structures of PEDOT were studied using FTIR spectra and UV/vis/NIR spectra. The results confirmed the formation of oxidized PEDOT polymer. The sensing property of the Pd/PEDOT:PSS thin film to the NH₃ vapor was investigated.     

Organic/inorganic hybrid solar cells based on SnS/SnO nanocrystals and MDMO-PPV

SnS/SnO heterojunction structured nanocrystals with zigzag rod-like connected morphology were prepared by using a simple two-step method. Bulk heterojunction solar cells were fabricated using the SnS/SnO nanocrystals blended with poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene) (MDMO-PPV) as the active layer. Compared with solar cells using SnS nanoparticles hybridized with MDMO-PPV as the active layer, the SnS/SnO devices showed better performance, with a power conversion efficiency higher by about one order in magnitude.     

Preparation of TiO2/PANI composites in the presence of surfactants and investigation of electrical properties

“In situ” polymerization was carried out in the presence of titanium dioxide (TiO₂) to synthesize TiO₂/polyaniline (TiO₂/PANI) composite in an aqueous medium containing anionic (sodium dodecylbenzenesulfonate), DBSNa, cationic (tetradecyltrimethylammonium bromide), TTAB, and nonionic surfactants (poly(ethylene oxide) (20) sorbitan monolaurate), Tween 20). The composites were characterized by FTIR, UV–vis spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Gouy balance measurements. The FTIR and UV–vis spectra reveal that the interaction between TiO₂/PANI composite and surfactants. The anionic and cationic surfactants incorporated with TiO₂/PANI composite structure. The stability of the composites in terms of direct-current electrical conductivity retention was studied in isothermal conditions. Electrical conductivity measurements indicate that the conductivity of TiO₂/PANI synthesized in the presence of the cationic surfactant has the highest conductivity value. All composites showed negative mass magnetic susceptibility values.     

Investigation of polyaniline processibility using GPC/UV–vis analysis

In this work, we characterized the molecular weight and UV–vis spectra of polyaniline (PANI) simultaneously using a gel permeation chromatography (GPC) system equipped with a photodiode array (PDA) detector. Therefore, we constructed correlations between weight average molecular weight (M_w) values and UV–vis spectral features such as the ratio of quinoid units/benzenoid units (Q/B ratio), and the B peak positions for the continuum of discrete chromatographic fractions of PANI emeraldine base (EB). The correlation is further verified by electrochemical techniques. Using this correlation, we analyzed newly synthesized PANIs and investigated how the synthesis and post-treatment conditions impact the quality, uniformity, and processibility of the PANIs. The study also reveals that the portions with low molecular weights of PANI are more sensitive to the process conditions than those with high molecular weights.     

表面修饰层厚度对Fe:ZnSe纳米晶光学性能的影响

利用硫代乙醇酸作为稳定剂在水相中合成了Fe:ZnSe/ZnS核/壳结构半导体纳米晶,研究了表面修饰层(壳层)厚度对产物光学性能的影响。XRD和UV-Vis吸收谱表明,合成的半导体纳米晶为核壳纳米晶,呈立方闪锌矿结构。TEM结果表明,产物分散性较好,尺寸均一,呈球形。PL结果表明,适当厚度的ZnS壳层能有效钝化Fe:ZnSe纳米晶表面的非辐射复合位点,当壳层过厚时,ZnS壳层产生的非辐射复合缺陷会导致PL强度下降。     

Facile and green route to highly luminescent ZnS-shelled CdSe nanocrystals

Highly luminescent CdSe/ZnS nanocrystals were obtained by adapting non-TOP-based synthesis and a subsequent two-phase ZnS shelling procedure:the core CdSe nanocrystals were synthesized in sole solvent paraffin liquid with cadmium oxide,elemental sele-nium,and oleic acid; the deposition of the ZnS shell was conducted by using zinc stearate in toluene and sodium sulfide in deionized water. The green and low-cost route was proved to be more efficient to constrain the size of core nanocrystals while tuning the ...     

EPR studies of blends of polyaniline with poly(methyl methacrylate-co-glycidyl methacrylate iminodiacetic acid)

A novel conductive blends of polyaniline (PANI) with poly(methyl methacrylate-co-glycidyl methacrylate iminodiacetic acid) (PANI–PMGI) was prepared by in situ dispersion polymerization. The PANI–PMGI blends were characterized by UV–vis, FTIR and electron paramagnetic resonance (EPR) spectra. The structure of the PANI–PMGI blends was similar to emeraldine salt proved by UV–vis and FTIR. The value of ΔH_pp, lineshape, g factor, N_s and A/B ratio of blends were investigated by EPR. The results of EPR indicated that the intermolecular interaction between PANI and PMGI was dependent on the content of PANI and temperature.     

Synthesis of a benzothiadiazole/thiophene-based oligomer for bulk heterojunction photovoltaic cells

An electron-donor–acceptor-type oligomer, oligo(B–EDOT₂–HT₃), composed of 2,1,3-benzothiadiazole (B), 3,4-ethylenedioxythiophene (EDOT) and 3-hexylthiophene (HT) units was synthesized via a multi-step procedure. The UV–vis absorption and photoluminescence emission peaks of the material in chloroform were observed at 510 and 660 nm, respectively. The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) levels of the material were estimated as ?3.47 and ?5.49 eV, respectively, corresponding to a band-gap of 1.97 eV. Bulk heterojunction photovoltaic cells were fabricated, using oligo(B–EDOT₂–HT₃) and PCBM, in the device configuration of ITO/PEDOT:PSS:6% glycerol/oligo(B–EDOT₂–HT₃):PCBM/LiF/Ag. The short-circuit current density, open-circuit voltage and fill factor of the device were estimated to be 1.44 mA/cm², 0.33 V and 0.36, respectively, with a 1:4 ratio of oligo(B–EDOT₂–HT₃) to PCBM, corresponding to an energy conversion efficiency of 0.17% under AM 1.5 illumination. One main reason for the low efficiency of the device was attributed to the low absorptivity of oligo(B–EDOT₂–HT₃) in the UV–vis spectral range.     

Colloidal and thermal stability of polyaniline-coated multi-core shell polystyrene latexes prepared using sulfonated N-hydroxyethyl aniline

Conductive polymer particles, poly(sulfonated N-hydroxyethyl aniline, SHEA)–polyaniline–poly(SHEA)–polystyrene (PSHEA–PANI–PSHEA–PSt) multi-core shell composite particles, were synthesized by chemical oxidation polymerization and an effect of poly(SHEA) on the colloidal and thermal stability enhancement was investigated. The PSHEA–PANI–PSHEA–PSt particles showed spherical shape and nearly monodisperse particle size distribution. Elemental analysis, UV–vis spectra, and Raman spectra revealed that polyaniline (PANI) was successfully coated onto the poly(SHEA) modified polystyrene particles. Conductivity of the PSHEA–PANI–PSHEA–PSt particle was higher than that of PANI–PSt particle after annealing at elevated temperature due to the non-volatile properties of poly(SHEA) as a co-dopant compared with inorganic dopants such as HCl. XPS analysis unveiled that the PANI in the PSHEA–PANI–PSHEA–PSt particle was co-doped by sulfonic acid in poly(SHEA), which increased conductive thermal stability of the particles.     

Synthesis and characterization of the core–shell Au covered LSMO manganite magnetic nanoparticles

In this work we report the synthesis and characterization of the nanomagnetic perovskite Sr manganites covered with Au shells having different thickness. La_2/3Sr_1/3MnO₃ (LSMO) manganite nanoparticles were first prepared by a sol–gel procedure. The LSMO manganite nanoparticles were chemically covered with gold to produce the core–shell samples. TEM, HRTEM and atomic emission spectroscopy techniques were used to determine the morphology and structure of the LSMO@Au nanoparticles. The bare LSMO nanoparticles have a mean diameter of around 4.4 nm while LSMO@Au nanoparticles have mean diameters between 7.15 and 4.8 nm depending on the gold quantity involved in the capping process. XRD studies show that both core and shell systems have the expected crystalline structure. The formation of the core–shell structure is sustained by the shift of the plasmon resonance wavelength maximum observed in the UV–vis absorbtion spectra of the LSMO@Au samples depending on the gold concentration. The magnetization versus applied magnetic field of the bare LSMO nanoparticles and LSMO@Au samples shows no hysteresis loop indicating the superparamagnetic behavior of these systems. The analysis of the temperature dependences of FC and ZFC magnetizations shows that for all the samples the axial anisotropy energy barriers are increased due to the magnetic dipolar interactions between neighbor nanoparticles.     

Polypyrrole nanoparticles and dye absorption properties

Polypyrrole (PPy) nanoparticles were prepared by using microemulsion polymerization processes at 3 °C. Particle characterization was performed by using FTIR, elementary analysis, UV–vis spectra and scanning electron microscope (SEM). The size of the nanoparticles varied from about 50 to 100 to 100 to 200 nm with the change in concentration of surfactant from 0.8 to 0.44 M. Polypyrrole nanoparticles were dedoped by a 10% NaOH solution, followed by a redoping process using a nuclear fast red kernechtrot dye, which has a sulfonate group. Dedoping changed the optical absorption properties of the nanoparticles.     

CeO_2:Eu~(3+)纳米晶的溶剂热合成及其发光性能

采用溶剂热技术成功合成晶粒小于100 nm的CeO_2-Eu~(3+)和CeO_2纳米晶,其中CeO_2-Eu~(3+)样品在紫外光激发下发出明亮的橙红色光.用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅立叶红外(FT-IR)、紫外漫反射(UV-vis)和光致发光(PL)等手段对产品的结构和性能进行分析和表征.结果表明:CeO_2-Eu~(3+)是纯立方萤石结构的单晶粉末;Eu~(3+)已成功掺入CeO_2晶格中,纳米级的CeO_2-Eu~(3+)和CeO_2的带隙能量分别是2.831和2.925 eV;CeO_2-Eu~(3+)纳米晶在593、612、632 nm处具有较强的发射峰(橙红光),而且较高的退火温度有利于提高样品的晶化度和荧光强度.