Uniform and ordered periodic mesoporous organosilica thin films by a facile solution growth approach

We demonstrate a novel solution growth method for synthesis of uniform and ordered periodic mesoporous organosilica (PMO) thin films on substrate. The approach is simple and facile, in which a substrate is immersed into a solution containing 1,2-bis(triethoxysilyl)ethane (BTSE) precursor, cetyltrimethylammonium bromide (CTAB) surfactant template, ammonia catalyst, ethanol, and decane. The precursors are hydrolyzed, cross-linked by ammonia catalyst, and assembled with the surfactant on the substrate to form highly ordered hexagonal mesostructures. The obtained mesoporous silica films possess substrate-size-dependent dimension, uniform and tunable thickness (30–100 nm), and ethane group incorporated frameworks. The obtained PMO films have been characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and grazing incidence small-angle X-ray scattering (GISAXS). The film thickness can be easily controlled by adjusting the reaction temperature. A formation mechanism of the ethane-bridged PMO films via CTAB directed sol–gel process is further proposed.     

脉冲激光法制备修饰纳米(ZnO-Eu_2O_3)/聚苯胺杂化薄膜材料

采用聚焦脉冲激光法(PLA-IT/SFL)制备修饰纳米(ZnO-Eu2O3)/聚苯胺有机溶胶及其杂化薄膜材料。TEM显示金属氧化物粒子粒径约为15nm且其在聚苯胺中有较高的稳定性。荧光光谱表明该杂化薄膜材料在紫外光照射下发出强烈的黄光。热分析表明该杂化薄膜比导电性聚苯胺(PAN-HCSA)薄膜具有更好的热稳定性。该杂化薄膜材料可望用于电致发光领域。     

Quantifying Water at the Organic Film/Hydroxylated Substrate Interface

A method, based on Fourier transform infrared-multiple internal reflection (FTIR-MIR) spectroscopy, for determining the amount and thickness of water at an organic film/hydroxylated substrate interface has been developed. The analysis uses a two-layered model, which takes into account: 1) water at the organic film/hydroxylated substrate interface, 2) water taken up by the organic film within the penetration depth of the evanescent wave and 3) change of the penetration depth as water displaces the organic film from the substrate. Experimentally, the method requires the application of an organic film, transparent or opaque, of sufficient thickness on a hydroxylated internal reflection element, which is used as the substrate. A water chamber is attached to the organic-coated specimen. After adding water to the chamber, FTIR-MIR spectra are taken automatically at specified time intervals without disturbing the specimen or the instrument. Water uptake in the organic films and FTIR-MIR spectra of water on the substrates are also obtained and used for the analysis. Results of examples of three organic films: a clear epoxy, an unmodified asphalt, and a pigmented ester, on a hydroxylated SiO₂-Si substrate were presented to demonstrate the method. The water layer at the interface for the ester and asphalt specimens was found to be much thicker than that for the epoxy, and this was attributed to the presence of a water-sensitive layer accumulated at the interface for the formers. The method should be equally applicable to studies of organic and inorganic compounds at the organic film/hydroxylated substrate interface and their transport rates through films adhered to a substrate.     

金属离子掺杂二氧化钛及水体光催化脱氮研究

采用溶胶-凝胶法制备了掺杂Ce^3＋、La^3＋、Ag^＋、Fe^3＋的TiO2光催化剂，以考察其薄膜和粉体形式对水中无机氮的光催化去除效果和活性．用所制备的催化剂对含氨氮-亚硝酸氮的混合液进行了光催化脱氮研究．本文利用UV—Vis吸收光谱、XRD和TEM对催化剂进行了表征．同时，对影响TiO2光催化效率的因素：如掺杂金属离子的种类、浓度、涂膜层数、反应液中有无Fe^2＋、不锈钢和玻璃载体、反应器的构型等进行了探讨，并对今后的研究进行展望．经过2h紫外光照射反应，实验最佳脱氮效果：金属离子掺杂TiO2薄膜型催化剂总氮去除率在30％左右，金属离子掺杂粉末型催化剂光催化最高总氮去除率可达41．7％．     

Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZθ stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 μm line width were obtained successfully.     

Ultrathin free-standing close-packed gold nanoparticle films: conductivity and Raman scattering enhancement

A simple filtration technique was developed to prepare large scale free-standing close-packed gold nanoparticle ultrathin films using metal hydroxide nanostrands as both barrier layer and sacrificial layer. As thin as 70 nm, centimeter scale robust free-standing gold nanoparticle thin film was obtained. The thickness of the films could be easily tuned by the filtration volumes. The electronic conductivities of these films varied with the size of the gold nanoparticles, post-treatment temperature, and thickness, respectively. The conductivity of the film prepared from 20 nm gold nanoparticles is higher than that of the film prepared from 40 nm gold nanoparticle by filtering the same filtration volume of their solution, respectively. Their conductivities are comparable to that of the 220 nm thick ITO film. Furthermore, these films demonstrated an average surface Raman scattering enhancement up to 6.59 × 10(5) for Rhodamine 6 G molecules on the film prepared from 40 nm gold nanoparticles. Due to a lot of nano interspaces generated from the close-packed structures, two abnormal enhancements and relative stronger intensities of the asymmetrical vibrations at 1534 and 1594 cm(-1) of R6G were observed, respectively. These robust free-standing gold nanoparticle films could be easily transferred onto various solid substrates and hold the potential application for electrodes and surface enhanced Raman detectors. This method is applicable for preparation of other nanoparticle free-standing thin films.     

Controlled Layer-by-Layer Formation of Ultrathin Oxide Films on Silver Island Films for Surface-Enhanced Raman Scattering Measurement

Methods for the controlled deposition of ultrathin metal oxide layers onto silver island films for surface-enhanced Raman scattering (SERS) measurements are reported. Two related deposition techniques are explored for thin film growth: a surface sol-gel method and atomic layer deposition. Both methods exhibit excellent control of the deposited film thickness to atomic level precision while conformally coating the complex structures found in silver island films. Coating of metal oxide films onto silver substrates provides a method for monitoring the distance dependence of SERS enhancements and offers a platform for exploring adsorption and interaction of analytes on dielectric surfaces. Analysis of the distance dependence of the Raman signal with increasing film thickness yields estimated silver particle sizes that are in agreement with microscopy, which is consistent with the layer-by-layer growth mechanism of uniform metal oxide films on the silver substrate. These methods can be easily extended to grow a variety of laminar or mixed metal oxide films for the exploration of interfacial phenomena.     

Preparation of monodispersed PNIPAm/silica composites and characterization of their thermal behaviors

Two types of thermosensitive poly(N-isopropylacrylamide) (PNIPAm)-silica organic/inorganic hybrid particles were successfully prepared in aqueous solution through a facile synthetic process. Silane coupler of vinyl organic groups connects the PNIPAm to silica. First, hybrid spheres were prepared by grafting PNIPAm polymers to VTMS (vinyl trimethoxysilane) silica spheres. The thickness of polymer shell on the silica surfaces could be easily controlled by varying the concentrations of NIPAm monomer. Second, another type of hybrid particle was fabricated by encapsulating PNIPAm polymer with silica materials. The PNIPAm polymers were completely encapsulated by silica shell. The morphologies and shell thickness were characterized through SEM and TEM. The variations of phase transition temperature of PNIPAm were measured using DSC.     

Humidity-Sensing Characteristics of Divalent-Metal-Doped Indium Oxide Thin Films

Metal-doped indium oxide thin films that have been prepared on glass substrates via a dip-coating method from an aqueous sol show a rapid decrease in electrical conductivity at room temperature (by approximately three orders of magnitude) when brought into contact with moist air. This observation is in contrast to the conductivities of nondoped indium oxide films that are independent of moisture. Thus, the doped films can be applied as a humidity sensor. The film thickness has no substantial effect on the sensing properties, probably because of the porous nature of the films that are prepared by a sol-gel process. To examine the effects of film morphology, a comparison between the humidity-sensing properties of the films that have been prepared from organic and aqueous sols also has been conducted. The roles of the doped metal ions are also discussed.     

Synthesis of nano polyaniline and poly-<Emphasis Type="Italic">o</Emphasis>-anisidine and applications in alkyd paint formulation to enhance the corrosion resistivity of mild steel

Protection of oxidizable metals against corrosion has now being intensively investigated, by applying or developing different methods such as coatings and conversion films; however, all reported methods involve environmentally hazardous materials. Conducting polymers have now been used as corrosion inhibitor coatings that are either chemically or electrochemically deposited on the metal substrate. The application of nanotechnology in the corrosion protection of metals has recently gained momentum. Environmental impact can also be improved by utilizing nanostructure particulates in coatings and eliminating the requirement of toxic solvents. We report here the synthesis of nanoparticles of polyaniline (PANI) and poly-o-anisidine (POA) using emulsion polymerization method in micellar solution of SDS and their anticorrosive property has been experimentally checked. The prepared nanoparticles have been characterized by FTIR and TEM. The nanoparticles of the synthesized polymers were dispersed in alkyd paint formulation for coatings on the metal surface (mild steel). The water absorption in the prepared coatings was also studied. The corrosion rate of polymeric film was determined by weight loss measurement and the surface morphology was examined by SEM. The nano PANI/Alkyd coatings showed considerable protection against corrosion than the POA/alkyd coatings.     

TiO_2/ZnO纳米多孔复合膜制备及光催化性能研究

分别采用水热处理和添加有机物的方法制备了TiO2/ZnO纳米多孔复合膜,利用XRD、SEM、TEM和EDS对薄膜进行了分析表征,通过甲基橙降解研究了多孔膜的光催化性能。结果表明:采用这两种方法都可获得具有孔洞特征的多孔复合膜,对添加有机物法制备的多孔膜进行的光催化降解实验表明该多孔膜光催化性能明显优于致密复合膜。     

Direct Electroplating of Lithium Cobalt Oxide Film on Platinum Substrate in 100°–200°C Aqueous Solution

Well crystallized, shape-formed, and electrochemically active lithium cobalt oxide (LiCoO₂) films are electroplated directly on an electron-conducting substrate in an aqueous solution using a soft solution processing that is economical, consumes less energy consuming, and is environmentally friendly. Although LiCoO₂ films are easily and economically prepared without any post-synthesis heat treatment, the estimated film properties show a possibility of using the deposited films as a cathode film for lithium rechargeable microbatteries. In addition, the soft solution processing reveals that an exact understanding of chemical reactions and the proper combination of the chemical reactions can create an advanced synthetic procedure.     

Surface roughness of AlN films deposited on negatively biased silicon and diamond substrates

Our previous studies on AlN microstructures have shown that smooth amorphous films (a-AlN) can be grown on negatively biased Si substrates by the versatile physical vapour deposition technique under reactive magnetron sputtering. These a-AlN films are produced by energetic Ar ion bombardment under negative bias whereas those grown without bias were columnar crystallized ones (c-AlN). Here, we show first that depositing an a-AlN layer on c-AlN/Si structures by switching a suitable bias to the Si substrate can efficiently reduce their surface roughness. We then extend this smoothening method to a c-AlN/Poly-crystallized diamond (PCD) structure to reduce its high surface roughness that hampers using such structures in SAW device design. In fact, the piezoelectric c-AlN surfaces grown on rough diamond surfaces are equally rough. Effectively, the a-AlN layer deposited on the c-AlN/PCD structure brings down the latter's RMS surface roughness to one tenth of its initial RMS roughness, as confirmed here by TEM and AFM observations. The insulating property of the diamond as biased substrate doesn't impede the growth of this a-AlN layer. This smoothening method is without process interruption, where simply a negative bias is switched on to the diamond substrate once the desired piezoelectric c-AlN film thickness as monitored here by in-situ reflectometry, is attained. This as-grown smoothening method can be therefore easily and rapidly implemented and can thus replace time-consuming and costly PCD ionic and/or mechanical polishing. Hopefully, the method can be advantageously applied to c-AlN/nano-crystallized diamond structures (NCD) where the NCD films are not prepared under rigorous conditions meant to minimize their surface roughness.     

High performance coating films cured by novel penetrating method: Anionic resin paints

This study deals with a method of curing paint film at ambient temperature with a film-penetrative crosslinker. The method is based on the phenomenon that, after a wet coating film becomes thermoplastic, it is dipped in an aqueous solution of crosslinker. The crosslinker then penetrates into the film, and the film can be cured with the passage of dipping time. Herein an anionic copolymer containing diacetone acrylamide was employed as the main resin and carbohydrazide as the film-penetrative crosslinker. Cured films can be prepared with a short dipping time using this method. Excellent films were obtained when they were dipped in a suitable crosslinker solution containing the proper organic solvents (accelerator of penetration rate) and an appropriate acid (promoter of the reaction). In particular, the adhesion after the water resistance test was excellent compared with that of the coating film obtained by the two-component coating method.     

Properties of organic–inorganic composite materials prepared from acrylic resin emulsions and colloidal silicas

To design an organic–inorganic composite material with colloidal silica as the inorganic component, an acrylic resin emulsion and an organic silane hybridized acrylic resin emulsion were prepared by emulsion polymerization. The organic–inorganic composite films were prepared by blending the emulsion and the colloidal silica. The contact angles for water, gloss at 60°, and the transparencies of those films were measured. The dispersion state of colloidal silica in films was observed with a scanning electron microscope (SEM) and a transmission electron microscope (TEM). From these results, the contact angle for water of the organic–inorganic composite film obtained from the silane hybridized acrylic resin emulsion was lower than that of the organic–inorganic composite film obtained from an acrylic resin emulsion. The contact angles for water in organic–inorganic composite films with colloidal silicas were lower than those of the films without the colloidal silicas. The films prepared from silane hybridized acrylic resin emulsion composites with colloidal silicas of less than 100 nm were more hydrophilic. SEM and TEM observations demonstrated that some aggregations of the small colloidal particle silica were densely dispersed on the film surface. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2051–2056, 2006     

Synthesis of nickel-filled carbon nanotubes at 350 °C

The deposition of nickel/amorphous carbon (Ni/a-C) films by a hybrid plasma process combining magnetron sputtering of a Ni target and plasma enhanced chemical vapor deposition using methane gas has been investigated. The formation of nickel nanowires encapsulated by a-C matrix has been demonstrated by transmission electron microscopy (TEM). The obtained nanowires array can be easily dispersed or can be simply converted to a Ni-filled CNT array by annealing at 350 °C as confirmed by TEM analysis. The developed fabrication method of Ni-filled CNT array is a low temperature technique compatible with substrates of low melting point.     

Metal Propionate Synthesis of Magnetoresistive La1−x(Ca,Sr)xMnO3 Thin Films

A flexible chemical solution deposition (CSD) method for the preparation of magnetoresistive La_1−x (Ca,Sr)x MnO₃thin films based completely on metal propionates is pre-sented.A number of polycrystalline thin films with varying stoichiometries were deposited on different substrate ma-terials at temperatures between 550° and 850°C. The crys-tallization behavior on selected substrates was found to de-pend on the thin film stoichiometry. Magnetoresistivity and magnetization were measured as a function of temperature. For the selected samples, a magnetic Curie temperature TC, a metal–semiconductor transition, and magnetoresistive behavior were observed. These measurements demon-strated that La_1−x(Ca,Sr)x MnO₃ thin films with properties well known from films deposited by PLD or sputtering can be prepared by a simple, propionate-based CSD method.     

Fabrication of a model cellulose surface from straw with an aqueous sodium hydroxide/thiourea solution

Model cellulose surfaces were prepared with both microcrystalline cellulose and cellulose isolated from wheat straw with different molecular weights. A sodium hydroxide/thiourea aqueous solution, instead of any organic solvents, worked as the solvent for dissolving cellulose, and model cellulose films were prepared by a two‐step method: first, the cellulose solution was deposited onto the surface of the substrate with the spin‐coating method, and second, the as‐prepared film was washed with deionized water to remove the impurities and was formed with a flattened surface. Atomic force microscopy was used to measure the morphology, surface roughness, and thickness of the cellulose thin films. X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray spectrometry were used to characterize the surface chemical information of the films. The results revealed that model cellulose surfaces could form from both kinds of cellulose. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The effect of incorporating carbon nanotubes in titania films used for the photocathode protection of 304 stainless steel

Composite films of TiO₂ and multiwall carbon nanotubes (MWCNTs) were prepared on 304 stainless steel (304 SS) by the sol–gel method and heat treatment. Their crystal phase and surface structure were characterized by X-ray diffraction and electron microscopy. The photoelectrochemical performance of the composite films in 3.0% NaCl solution was evaluated by electrochemical measurements under UV irradiation and dark conditions. Since highly conductive MWCNTs in the TiO₂ films can transport the photo-generated electrons easily and quickly to the metal substrate, the MWCNT/TiO₂ composite films exhibited three times the photocurrent and the half the charge transfer resistance of pure TiO₂ films, and provide a much better photocathode protection for 304 SS.     

Sol–Gel Synthesis of Perovskite-Type Lanthanum Manganite Thin Films and Fine Powders Using Metal Acetylacetonate and Poly(vinyl alcohol)

A novel sol–gel process was developed for preparing thin films and fine powders of lanthanum manganite (LaMnO₃) with perovskite-type structure. Lanthanum and manganese acetylacetonate powders could be easily dissolved in a mixed solution of methyl alcohol and ethylene glycol (or methyl alcohol and propionic acid) to give a spinnable organic solution as a starting material. Pretreatment of a substrate by poly(vinyl alcohol) (PVA) aqueous solution, a gel former, made it possible to deposit a thin film as well as to lower the sintering temperature.