可溶性含萘环结构聚醚酮酮醚酮酮的合成

以1-萘酚和1,4-二(4-氟苯羰基)苯为起始原料,经亲核取代反应,合成了一种新的含萘环结构芳醚单体1,4-[4-(1-萘氧基)苯羰基]苯(BNOBB)。以路易斯酸无水三氯化铝(AlCl 3)为催化剂,将该单体与对苯二甲酰氯(TPC)和间苯二甲酰氯(IPC)进行缩聚,合成了一种主链含萘环结构的无规共聚物聚醚酮酮醚酮酮(PEKKEKK)。采用傅里叶变换红外光谱仪、核磁共振、差示扫描量热仪、热重分析仪和广角X射线衍射等技术手段对PEKKEKK树脂的结构和性能进行测试。结果表明,该树脂为非晶态结构,具有较高的玻璃化转变温度(T g>181℃)和热分解温度(T 5%>502℃);易溶解于氯仿、1,2-二氯乙烷、N,N-二甲基乙酰胺等有机溶剂中,可涂膜获得透明薄膜;拉伸强度大于83 MPa,力学性能较好。     

Nanoporous TiO2 films prepared by thermal rapid treatment (TRT)

Nanoporous TiO₂ films were fabricated by thermal rapid treatment (TRT) of the TiO₂ film which was previously deposited on a substrate by liquid phase deposition. The TiO₂ films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-VIS diffuse reflectance spectroscopy (UV-VIS DRS). Photocatalytic activity of nanoporous TiO₂ coating was assessed by the photocatalytic degradation of methylene blue aqueous solution.     

Preparation of active layers in polymer solar cells by aerosol jet printing

Active layers of polymer solar cells were prepared by aerosol jet printing of organic inks. Various solvents and additives with high boiling points were screened for the preparation of high-quality polymer films. The effects on device performance of treating the films by thermal and solvent vapor annealing were also investigated. The components of the solvent were important for controlling the drying rate of the liquid films, reducing the number of particle-like protrusions on the film surface, and realizing high molecular ordering in the polymer phases. The optimized solar cell device with poly(3-hexylthiophene) and a C(60) derivative showed a high fill factor of 67% and power conversion efficiency of 2.53% without thermal annealing. The combination of poly[N-9-heptadecanyl-2,7-carbazole-alt-3,6-bis(thiophen-5-yl)-2,5-diethylhexyl-2,5-dihydropyrrolo-[3,4-]pyrrole-1,4-dione] and a C(70) derivative led to power conversion efficiency of 3.92 and 3.14% for device areas of 0.03 and 1 cm(2), respectively.     

N-type crystalline silicon films free of amorphous silicon deposited on glass by HCl addition using hot wire chemical vapour deposition

Since n-type crystalline silicon films have the electric property much better than those of hydrogenated amorphous and microcrystalline silicon films, they can enhance the performance of advanced electronic devices such as solar cells and thin film transistors (TFTs). Since the formation of amorphous silicon is unavoidable in the low temperature deposition of microcrystalline silicon on a glass substrate at temperatures less than 550 degrees C in the plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition (HWCVD), crystalline silicon films have not been deposited directly on a glass substrate but fabricated by the post treatment of amorphous silicon films. In this work, by adding the HCl gas, amorphous silicon-free n-type crystalline silicon films could be deposited directly on a glass substrate by HWCVD. The resistivity of the n-type crystalline silicon film for the flow rate ratio of [HCl]/[SiH4] = 7.5 and [PH3]/[SiH4] = 0.042 was 5.31 x 10(-4) ohms cm, which is comparable to the resistivity 1.23 x 10(-3) ohms cm of films prepared by thermal annealing of amorphous silicon films. The absence of amorphous silicon in the film could be confirmed by high resolution transmission electron microscopy.     

Microstructure Control of Nanoporous Silica Thin Film Prepared by Sol-gel Process

Nanoporous silica films were prepared by sol-gel process with base, acid and base/acid two-step catalysis.Transmission electron microscope （TEM） and particle size analyzer were used to characterize the microstructure and the particle size distribution of the sols. Scanning electron microscopy （SEM）, atomic force microscopy （AFM） and spectroscopic ellipsometer were used to characterize the surface microstructure and the optical properties of the silica films. Stability of the sols during long-term storage was investigated. Moreover,the dispersion relation of the optical constants of the silica films, and the control of the microstructure and properties of the films by changing the catalysis conditions during sol-gel process were also discussed.     

Conductivity and nanoscale morphology of thin films prepared from indolo[2,3-a]carbazole and 11,12-dioctylindolo[2,3-a]carbazole

A systematic study on the thin film morphology of heteroacenic derivatives such as indolo[2,3-a]carbazole and 11,12-dioctylindolo[2,3-a]carbazole has been carried out using scanning force microscopy and optical microscopy techniques. The investigation has comprised the preparation of a series of thin films by combining different solvents (dimethylformamide and tetrahydrofurane), substrates (glass, gold, silicon and aluminium) and deposition techniques (spin coating and thermal evaporation) we found a wide variety of self-assembled structures. In addition, conductivity measurements have been performed, showing a very large spread in conductivity values. Some of the samples give quite high conductivity while others conduct very poorly, even in the case of samples prepared with essentially the same conditions. These results indicate that morphology is very critical for the final conductivity of the thin films. In addition we conclude that for some of the films prepared the homogeneous thin film approximation must be revised otherwise obtained conductivity measurements lead to significant error.     

含有氢键的聚酰亚胺薄膜的制备和性能表征

以对硝基苯甲酸为原料,通过酰氯化、酰化、还原反应成功合成了4,4’-二氨基苯酰替苯胺(DBN),DBN分别和3,3’,4,4’-联苯四酸二酐(BPDA)、均苯四甲酸二酐(PMDA)通过两步法缩聚制备出聚酰亚胺薄膜,用红外(FT-IR),差示扫描量热仪(DSC)和热重分析(TGA),拉伸测试表征其结构和性能,结果表明,成功合成了含有酰胺键的聚酰亚胺薄膜,并且酰胺键的N-H分别和酰亚胺环中的C-N和C=O形成了氢键。将其与4,4’-二氨基二苯醚(ODA)聚酰亚胺薄膜相比,对应二酐(BPDA和PMDA)分别和DBN制备的聚酰亚胺薄膜表现出了优异的热性能和耐溶剂性,尤其是拉伸强度有了显著的提高。     

Electrophoretic deposition of composite films from solutions of conjugated polymers and their supramolecular complexes with carbon nanotubes

Electrophoretic deposition (EPD) method has been developed for the fabrication of composite poly[3-(3-N,N-diethylaminopropoxy)thiophene] (PDAOT) and poly[9,9-bis(diethylaminopropyl)-2,7-fluorene-co-1,4-phenylene] (PDAFP) films. The kinetics of deposition was studied using quartz crystal microbalance method. The composite films were obtained as monolayers or laminates. Film composition and optical absorption properties can be controlled. Composite films composed of PDAOT, PDAFP, and single-walled carbon nanotubes (SWNTs) were obtained using the supramolecular polymer complexes with SWNTs. The films were studied by UV-vis absorption, electron microscopy and impedance spectroscopy methods. The composite films and the EPD method for their fabrication are promising for the development of photovoltaic devices.     

Titania-assisted dispersion of carboxylated single-walled carbon nanotubes in a ZnO sol for transparent conducting hybrid films

We report a facile chemical route for stabilizing a dispersion of carboxylated single-walled carbon nanotubes (SWCNTs) in a ZnO sol. The dispersion is stabilized via capping of the carboxyl groups on the SWCNT surface by a titania layer, which was confirmed by Fourier transform infrared spectroscopy and transmission electron microscopy. We also demonstrate that the conductivity of the films prepared from the SWCNT/TiO(x)/ZnO sol is dramatically enhanced by thermal treatment and that the thermal stability of the hybridized films with the ZnO sol is notably improved relative to that of a pristine SWCNT film. The structural and chemical changes of the fabricated films were characterized by Raman spectroscopy. As one application, it was presented that thermally treated SWCNT/TiO(x)/ZnO hybrid thin film sensors showed hydrogen sensing characteristics even at room temperature.     

Ionization constants of ginkgolide B in aqueous solution

The thermodynamic ionization constants (pK(a)(1), pK(a)(2), and pK(a)(3)) of ginkgolide B (9H-1,7a-(epoxymethano)-1H,6aH-cyclopenta[c]furo[2,3-b]furo-[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12-(4H)-trione, 3-tert-butylhexahydro-4,7b,11-trihydroxy-8-methyl-) in aqueous solution have been settled by pH-metric and NMR studies. The three macroscopic pK(a) values as well as the water solubility and the water/n-octanol partition coefficient have been extracted from pH-metric data by means of a nonlinear regression methodology. NMR spectroscopy provided confirmation of the values of the macroscopic constants, information about the effective ionization pathways, and an estimation of the proportions of the various forms under physiologically relevant conditions.     

Real-time microscopy of graphene growth on epitaxial metal films: role of template thickness and strain

Epitaxial transition metal films have recently been introduced as substrates for the scalable synthesis of transferable graphene. Here, real-time microscopy is used to study graphene growth on epitaxial Ru films on sapphire. At high temperatures, high-quality graphene grows in macroscopic (>100 μm) domains to full surface coverage. Graphene nucleation and growth characteristics on thin (100 nm) Ru films are consistent with a pure surface chemical vapor deposition process, without detectable contributions from C segregation. Experiments on thicker (1 μm) films show a systematic suppression of the C uptake into the metal to levels substantially below those expected from bulk C solubility data, consistent with a strain-induced reduction of the C solubility due to gas bubbles acting as stressors in the epitaxial Ru films. The results identify two powerful approaches--i) limiting the template thickness and ii) tuning the interstitial C solubility via strain--for controlling graphene growth on metals with high C solubility, such as Ru, Pt, Rh, Co, and Ni.     

Crystallization by excimer laser annealing for a-Si:H films with low hydrogen content prepared by Cat-CVD

Crystallization by excimer-laser annealing (ELA) for hydrogenated amorphous silicon (a-Si:H) films with low hydrogen content (C_H) prepared by catalytic chemical vapor deposition (Cat-CVD) was systematically studied. From optical microscopy images, no hydrogen bubbling was observed during ELA, even without a dehydrogenation process. As the laser energy density was increased to 300 mJ cm⁻², the full width at half-maximum of the Raman signal from the crystalline phase decreased to approximately 4 cm⁻¹. This value is almost equal to or even smaller than that reported for polycrystalline Si (poly-Si) films prepared from plasma-enhanced CVD (PECVD) a-Si:H films by ELA so far. The average grain size, estimated from scanning electron microscopy, was approximately 500 nm for C_H of 1.3 at.%. On the other hand, the grain size of poly-Si films prepared from PECVD a-Si:H films with a dehydrogenation process was only 200 nm. The technique using Cat-CVD films is expected to be used for fabrication of low-temperature high-mobility thin-film transistors.     

Growth and characterisation of SiC films deposited on a-SiO2/Si (100) substrates

Abstract

The growth of polycrystalline SiC films has been carried out by low pressure chemical vapour deposition in a horizontal quartz reaction chamber using tetramethylsilane and H2 as the precursor gas mixture. Silicon (100) wafers were used as substrates. A thin Si O₂ amorphous layer of ~6 nm was formed before SiC deposition to reduce the strain induced by the 8% difference in thermal expansion coefficients between SiC and Si. Samples were. analysed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and infrared reflectivity. The structure of films grown at temperatures between 950 and 1150°C varies from amorphous to polycrystalline SiC. Preferential [111] orientation and columnar growth of polycrystalline films develops with increasing temperature.

MST/3317     

Ultrathin ruthenium(II) complex-H4SiW12O40 multilayer film

A dipolar Ru(II) complex, [(bpy)2Ru(bpbh)Ru(bpy)2](ClO4)4 {where bpbh = 1,6-bis-[2-(2-pyridyl) benzimidazoyl]hexane, bpy = 2,2'-bipyridine}, was synthesized and characterized. A multilayer film of at least 18 layers was successfully prepared by alternating adsorption of H4SiW12O40 and [Ru2(bpy)4(bpbh)](ClO4)4 by electrostatic layer-by-layer self-assembly. The multilayer films were studied by ultraviolet-visible and X-ray photoelectron spectroscopy, atomic force microscopy, and cyclic voltammetry.     

Microstructure of Epitaxial La_(0.7)Ca_(0.3)MnO_3 Thin Films Deposited by Direct Current Magnetron Sputtering on LaAlO_3 Substrate

Transmission electron microscopy (TEM) and high resolution electron microscopy (HREM) have been used to study the microstructural properties of La0.7Ca0.3MnO3 films on (001) LaAlO3 substrates prepared by direct current magnetron sputtering technique.The as-grown thin films with different thickness are perfectly coherent with the substrates.The film suffers a tetragonal deformation in the area near the interface between the film and the substrate.With increasing thickness, the film is partially relaxed.It was found that La0.7Ca0.3MnO3 films consist of two types of oriented domains described as: (1) (110)f[001]f||(001)s[100]sand (110)f[001]f||(001)s[100]s and (2) (110)f[001]f||(001)s[010]s and (110)f[001]f//(001)s[010]s.Upon annealing, the film is relaxed by the formation of misfit dislocations.Other than misfit dislocations, two types of threading dislocations with Burgers vector of <100> and <110> were also identified.     

The influence of different cross-linking reactions and glycerol addition on thermal and mechanical properties of biodegradable gliadin-based film

In this study gliadin solutions previously cross-linked by 1-(3-dimethylaminopropyl)-3-1-ethylcarbodiimide hydrochloride/n-hydroxysuccinimide (EDC/NHS) and l-cysteine were prepared with different plasticizer concentrations. The obtained films were investigated through mechanical behavior (Young's modulus and elongation at break), thermal characteristics (differential scanning calorimetry and thermogravimetric analysis), swelling and water solubility, FTIR measurements and scanning electron microscopy. The relationships between the gliadin structure and the mechanical, thermal and morphological properties were affected by protein conformational changes during the cross-linking reaction. On the other hand, the reaction mechanism was strongly dependent on the glycerol content.     

Preparation of nanoporous poly(methyl silsesquioxanes) films using PS-b-P4VP as template

Nanoporous poly(methyl silsesquioxane) (PMSSQ) film was prepared through the templating of an amphiphilic block copolymer, poly(styrene-4-vinyl pyridine) (PS-b-P4VP). The experimental and theoretical studies suggest that the intermolecular hydrogen bonding is existed between the PMSSQ precursor and PS-b-P4VP. The miscible hybrid and the narrow thermal decomposition of the PS-b-P4VP lead to nanopores in the prepared films from the results of TGA, AFM, and TEM. The effects of the loading ratio on the morphology and properties of the prepared nanoporous PMSSQ films were investigated. The TEM and AFM studies show that the uniform pore morphology with pore size 10-15 nm can be prepared from a modest porogen loading level for the optimum intermolecular hydrogen bonding. The refractive index and dielectric constant of the prepared nanoporous films decreases with an increase in PS-b-P4VP loading. On the other hand, the porosity increases with an increasing PS-b-P4VP loading. This study demonstrates a methodology to control pore morphology and properties of the nanoporous PMSSQ films through the templating of PS-b-P4VP.     

Rapid crystallization of a-Si:H films with various silicon-to-hydrogen bonding configurations using rapid energy transfer annealing

Hydrogenated amorphous silicon (a-Si:H) films were prepared by changing substrate temperature of plasma-enhanced chemical vapor deposition to induce different contents of monohydride and polyhydride bonds, which were then crystallized into polysilicon (poly-Si) films by rapid energy transfer annealing. Fourier transform infrared and transmission spectra show that the formation of numerous polyhydride bonds increases the hydrogen content and reduces the refractive index of a-Si:H films. The rise in the concentration of polyhydride bonds in as-deposited a-Si:H films can result in the increase of ultraviolet reflectance, small peak shift, and change in full width at half maximum of Raman scattering and X-ray diffraction peaks of the obtained poly-Si films after annealing. These results demonstrate that high-concentration polyhydride bonds can promote the rapid crystallization of a-Si:H and obtain high-crystallinity poly-Si films. Transmission electron microscopy identifies that the poly-Si films have the typical dendrite-like grain structure.     

Polyimide/sepiolite nanocomposite films: Preparation, morphology and properties

Polyimide/sepiolite nanocomposite films have been prepared via an in situ polymerization method. The process involves the dispersion of sepioite in N,N-dimethylacetamide, polycondensation of 2,2′-bis [4-(3,4-dicarboxyphenoxy) phenyl] propane dianhydride and 4,4′-oxydianiline in the presence of sepiolite suspension to form poly(amic acid), and the thermal imidization of poly(amic acid)/sepiolite nanocomposite. The morphology, thermal and mechanical performance, and water absorption of nanocomposite films were systematically studied with various sepiolite contents. The results indicated that sepiolite was dispersed homogeneously at a nanometer scale in polyimide matrix. Owing to such nanodispersion of sepiolite, the polyimide/sepiolite nanocomposite films exhibit dramatic improvements on the mechanical properties and the coefficient of thermal expansion while fine thermal stability and low water absorption capacity were also maintained. When the sepiolite content increased to 16% the polyimide/sepiolite nanocomposite film achieved as much as 41% and 94% increase on the tensile strength and modulus respectively, and 50% decreased in coefficient of thermal expansion.     

Structural and chemical investigation of CdSe crystals deposited in a nanoporous sol-gel: Effect of chemistry and defects on photovoltaic properties

Nanoporous cadmium selenide films were prepared by electro crystallization inside a nanoporous SiO₂ network, prepared by a sol-gel process on an electrically conducting indium tin oxide (ITO) substrate. Subsequent removal of the SiO₂ template should, according to literature reports, give a nanoporous network of CdSe in electronic contact with the substrate. The structure/morphology of the film was explored during the preparative steps by grazing incidence small/wide angle X-ray scattering, scanning electron microscopy and atomic force microscopy. The chemistry was studied by time of flight secondary ion mass spectrometry methodologies, such as imaging and depth profiling that maps the in-plane and in-depth distribution of chemistry, i.e. full 3-dimensional chemical imaging of the nanoporous CdSe layer. Finally, the nanoporous CdSe films were tested as electron conductors in hybrid organic/inorganic solar cells employing CdSe as the electron conductor and poly-3-hexylthiophene as the hole conductor. ITO and gold served as the electrodes. It was found that removal of the SiO₂ from the micellar SiO₂-CdSe nanostructure led to a collapse of the resulting CdSe structure with a poor structural conservation. Furthermore, a high pinhole density in the sol-gel resulted in a high degree of shunting paths that led to poor photovoltaic properties.