Sol-Gel Derived Macroporous Titania Films Prepared from the System Containing Poly(ethylene glycol) Together with Long-Chain Alcohols

The effect of alcohol-type on macroscopic morphology has been examined for the macroporous titania (TIO₂) films prepared by a sol-gel dip-coating method from the system containing poly(ethylene glycol) (PEG) and alcohols having larger alkyl groups than ethanol. The phase separation is enhanced by decreasing the compatibility between the solvent mixture and PEG as long as the polycondensation rate does not increase greatly. In the 1-butanol system, macroporous morphology appears clearly even at higher relative humidity as 70% RH due to the slower polycondensation. In contrast, the macroscopic domain formation is completely suppressed by the rapid polycondensation in the 2-propanol system.     

Macroporous Morphology of the Titania Films Prepared by a Sol-Gel Dip-Coating Method from the System Containing Poly(Ethylene Glycol). I. Effect of Humidity

The influence of humidity upon the macroporous morphology of the titania films has been studied for a sol-gel dip-coating system containing poly(ethylene glycol) (PEG). The water adsorption from the ambient atmosphere modifies the polycondensation rate of TiO2 oligomer and the phase separation rate between the TiO2-PEG complex and solvent mixture, and greatly varies the macroscopic morphology of the resultant TiO2 film.     

Macroporous Morphology of the Titania Films Prepared by a Sol-Gel Dip-Coating Method from the System Containing Poly(Ethylene Glycol). III. Effect of Chemical Additives

The variation of macroporous morphology has been studied for the titania (TIO₂) films prepared by a sol-gel dip-coating method from the system containing poly(ethylene glycol) (PEG) under the addition of various types of organic solvents. The influence of externally-added solvent is interpreted by considering the compatibility between PEG and the solvent mixture, the volatility of the solvent mixture, and the polycondensation rate of titania oligomers. The macroscopic domain formation is remarkable when the compatibility between the solvent mixture and PEG is relatively poor and the boiling point of external solvent is relatively low.     

Macroporous Morphology of the Titania Films Prepared by a Sol-Gel Dip-Coating Method from the System Containing Poly(Ethylene Glycol). II. Effect of Solution Composition

The influences of water and alkoxide concentrations, as well as the relative humidity upon the macroporous morphology of the titania (TiO2) films have been studied for a sol-gel dip-coating system containing poly(ethylene glycol) (PEG). The distribution of resultant morphology against the withdrawal speed and relative humidity is varied significantly by mainly modifying the polycondensation and phase separation processes during the dipping operation, even by the small change in starting composition of the dipping solution.     

Phase Separation in Methylsiloxane Sol-Gel Systems in a Small Confined Space

The organo-siloxane gel with co-continuous structure derived from methyltrimethoxysilane (MTMS) was synthesized in a confined space between parallel plates by inducing spinodal decomposition during sol-gel transition. The resultant gel morphology was 3-dimensionally observed by laser scanning confocal microscopy (LSCM). The sliced LSCM photographs revealed that the confined gels have inhomogeneity perpendicular to the plate, exhibiting a layered structure. The layered structure can be divided into three regions according to their morphology; interface, near-surface layer, bulk phase. The organo-siloxane depletion layer had formed in the vicinity of both hydrophobic and hydrophilic plates, and the bulk phase had formed slight away from the plates exhibited co-continuous structure. In addition, the confined gels exhibited no shrinkage during drying process that resulted in the larger domain size compared to the monolithic gel. The attractive interaction between the plates and the resultant organo-siloxane phase accounts for the inhibition of shrinkage of confined gels.     

Macroporous Morphology of the Titania Films Prepared by a Sol-Gel Dip-Coating Method from the System Containing Poly(ethylene glycol): Effects of Molecular Weight and Dipping Temperature

Macroporous morphology has been examined for the titania (TiO₂) films prepared by a sol-gel dip-coating method from the system containing poly(ethylene glycol) (PEG) under the variations of molecular weight of PEG and dipping temperature. The macroporous morphology is observed only within the limited range of molecular weight because the compatibility between PEG and the solvent mixture is quite sensitive to the molecular weight. The macroscopic domain formation is enhanced at higher withdrawal speed when the dipping temperature is raised, suggesting that the fluidity reduction and the phase separation are more accelerated than the polycondensation due to the enhanced solvent evaporation.     

Preparation and Characterizations of TiO2/Organically Modified Silane Composite Materials Produced by the Sol-Gel Method

TiO₂/organically modified silane (ORMOSIL) composite materials produced by the sol-gel method were studied for optical waveguide applications. High optical quality waveguiding films on different substrates, including silicon, gallium arsenide, silica/silicon substrates, and microscope glass slides, were prepared from high titanium content (0.2 molar) ÿ-glycidoxypropyltrimethoxysilane at low temperature. Scanning electron microscopy (SEM), atomic force microscopy (AFM), differential thermal analysis (DTA), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the optical and structural properties of the composite films. The TGA/DTA results showed that the organic compounds in the film would tend to decompose in the temperature range from 200°C to 500°C. SEM and AFM results showed that a dense and porous-free composite material film could be obtained at the heat treatment temperature of 100°C. It was also shown that ORMOSIL is integrated in the glass, providing low shrinkage and high cracking resistance. The propagation loss properties of the composite films were also investigated. About 1.1 dB/cm propagation loss of the planar waveguide film was obtained at the wavelength of 633 nm.     

A Spectroscopic Study of the Effects of Various Solvents and Sol-Gel Hosts on the Chemical and Photochemical Properties of Thionin and Nile Blue A

Tetraethyl orthosilicate (TEOS)-based gels were doped with two optically active organic indicators, thionin and nile blue A. Before trapping in a sol-gel host, thionin and nile blue A were both evaluated for solvent and protonation effects on their spectral properties. Only extreme pH values provided by HCl, NaOH, and NH₄OH produced new absorption and/or fluorescence bands. Introduction of nile blue A into alkaline environments (0.1N NaOH, NH₄OH) results in the appearance of a broad absorption band centered near 520 nm whereas highly acidic environments (1N HCl) show a reduction of the 635 nm absorption peak accompanied by an absorption band located near 460 nm. A marked decrease is observed in the optical density of thionin in 1N HCl solution which results in a reduction in the fluorescence intensity. The absorption and fluorescence spectra also reveal a decrease in a pH 11 solution of NH₄OH as compared to neutral conditions. Both dyes formed dimers when the sol-gel host, initially synthesized with TEOS, was organically modified with methyltrimethoxysilane (MTMS). However, thionin dimers were present in all silica-based sol-gel compositions, as evidenced by the absorption and fluorescence spectra. Substitution of MTMS for some of the TEOS in the gel matrix resulted in blue shifts in the absorption and fluorescence spectra of nile blue A. The absorption peak shifted 50 nm to 596 nm whereas the fluorescence shifted around 40 nm to 635 nm. These blue shifts resulted from the reduced polarity of the silica-based xerogel. Thionin also exhibited shifts in its absorption and fluorescence spectra with organic modification by MTMS. The absorption shifted approximately 3 nm to 595 nm while the fluorescence maximum decreased 7 nm to 630 nm. The blue shifts in the spectra of thionin with additions of MTMS were attributed to surface sites that altered the molecular structure of the adsorbed thionin molecules.     

亲水有机相-含盐水两相体系的形成机理与分相能力

亲水有机相-含盐水两相体系的形成机理与分相能力;亲水有机相;含盐水相;两相体系;分相机理;分相能力     

Cholesterol Alters the Phase Separation in Model Membranes Containing hBest1

Human retinal pigment epithelial (RPE) cells express the transmembrane Ca²⁺-dependent Cl⁻ channel bestrophin-1 (hBest1) of the plasma membrane. Mutations in the hBest1 protein are associated with the development of distinct pathological conditions known as bestrophinopathies. The interactions between hBest1 and plasma membrane lipids (cholesterol (Chol), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and sphingomyelin (SM)) determine its lateral organization and surface dynamics, i.e., their miscibility or phase separation. Using the surface pressure/mean molecular area (π/A) isotherms, hysteresis and compressibility moduli (C_s⁻¹) of hBest1/POPC/Chol and hBest1/SM/Chol composite Langmuir monolayers, we established that the films are in an LE (liquid-expanded) or LE-LC (liquid-condensed) state, the components are well-mixed and the Ca²⁺ ions have a condensing effect on the surface molecular organization. Cholesterol causes a decrease in the elasticity of both films and a decrease in the ΔG_mix^π values (reduction of phase separation) of hBest1/POPC/Chol films. For the hBest1/SM/Chol monolayers, the negative values of ΔG_mix^π are retained and equalized with the values of ΔG_mix^π in the hBest1/POPC/Chol films. Shifts in phase separation/miscibility by cholesterol can lead to changes in the structure and localization of hBest1 in the lipid rafts and its channel functions.     

Synthesis of Bi2O3 and Bi4(SiO4)3 Thin Films by the Sol-Gel Method

Bi2O3 thin films were prepared by dipping silica slides in ethanolic solutions of tris(2,2-6,6-tetramethylheptane-3, 5-dionato)bismuth(III) [Bi(dpm)3] [1] and heating in air at temperatures 500°C. Bi4(SiO4)3 homogeneous thin films were obtained from the reaction of the bismuth oxide coating with the silica glass substrate at temperatures higher than 700°C. For heat treatments at temperatures between 600°C and 700°C, Bi2SiO5 coatings were obtained. The composition and microstructure evolution of the films were determined by Secondary Ion-Mass Spectrometry (SIMS), X-Ray Photoelectron Spectroscopy (XPS) and Glancing Angle X-Ray Diffraction (GA-XRD). The synthesis procedure was reproducible and allowed the control of the Bi2O3 phase composition. Moreover, the thin film annealing parameters were correlated with the formation of bismuth silicates, among which Bi4(SiO4)3 (BSO) is very appealing for the production of fast light-output scintillators [2].     

La0.7-xGdxSr0.3MnO3中的相分离和输运行为

研究了La0.7-xGdxSr0.3MnO3(x=0．00，0．10，0．15，0．20，0．30，0．40，0．50，0．60，0．70)体系的M-T曲线、M-H曲线、ESR曲线、ρ-T曲线和MR-T曲线。实验结果表明：随着Gd掺杂的增加，体系从长程铁磁有序向自旋团簇玻璃态和反铁磁状态转变，x=0.30和0.40时，样品在Tc以上温区发生相分离；高掺杂时的输运行为在其磁背景下发生异常，Gd掺杂引起的磁结构的变化将导致CMR效应。     

Characterization of the Sol-Gel Process Using Raman Spectroscopy Organically Modified Silica Gels Prepared Via the Formic Acid-Alkoxide Route

For precursor mixtures containing tetraethoxysilane (TEOS) and phenyltriethoxysilane (PhTREOS), time of gelation can be reduced by up to two orders of magnitude depending on reaction conditions employed when reacting the silicon alkoxide mixture with formic acid instead of water. Results indicate that time of gelation depends on the amount of PhTREOS in the precursor mixture. Within the range of concentrations investigated, an exponential law describes best the dependence of reduced time of gelation on the molar fraction of PhTREOS. Therefore, we conclude that the phenyl ring acts as a steric hindrance to network formation. Raman spectroscopy is used to characterize the reaction between the alkoxide mixture and formic acid. During the acidolysis reaction, ethanol is formed as an intermediate. A preliminary reaction scheme is proposed to account for the time dependence of species involved. Furthermore, Raman spectroscopy is successfully employed to monitor the effects of post-gelation thermal treatment of the gel samples. The effects observed are interpreted with a model of a phenyl ring trapped in a siloxane cage.     

Effect of Diluent Mixture on Porous Structure of Polyphenylene Sulfide via Thermally Induced Phase Separation

Polyphenylene sulfide (PPS) microporous membranes were prepared via the thermally induced phase separation process using diluent mixtures of diphenyl ether (DPE) and diphenyl ketone (DPK). The effects of DPE ratio to DPK in the diluent mixture on the microstructure were investigated. The results showed that the pore morphology of the membranes prepared from the diluent mixture was different from those of fabricated from pure diluents. Moreover, the pore structures of the membranes were changed along with the variation of the diluent composition.     

Aggregation Behavior of Alkoxide-Derived Silica in Sol-Gel Process in Presence of Poly(ethylene oxide)

Growth behavior of silica in an acid catalyzed sol-gel process from silicon alkoxide in the presence of poly(ethylene oxide), PEO, was investigated by in situ small angle X-ray scattering, SAXS, and ²⁹Si NMR measurements. The results of SAXS, that aggregation and gel formation behaviors of silica were affected by the presence of PEO, suggested a strong attractive interaction between silica oligomers and PEO. A possible reaction scheme of silica in the presence of PEO is as follows; (1) PEO and small silica oligomers coexist in the solution without specific interaction just after hydrolysis of the silicon alkoxide. (2) With the progress of condensation, a ramified aggregated complex between PEO and silica oligomers is formed, which is characterized by larger apparent value of radius of gyration and smaller fractal dimension than in the PEO-free system. (3) After gelation, the fractal dimension of scatterers remains to be smaller than that in the PEO-free system, because PEO associated with the silica network inhibits aggregation within the gel networks. Furthermore, PEO inhibits the condensation in the aging and in the drying process, leading to less strongly crosslinked dry gel. A temporal maximum in the time evolution of R_g was observed for the samples separated into two phases with their characteristic domain size being larger than several micrometers. This is considered to be a phenomenon related to increase and divergence of correlation length near and at the critical point.     

栀子苷在乙腈水体系中诱导相分离分配行为

研究了栀子乙腈水提取液中的栀子苷在诱导相分离后在两相中的分配行为,建立了乙腈/水分相体系分离纯化栀子苷的新方法。 重点考察了能使乙腈/水体系分相的诱导剂的种类,分析了诱导剂的组成比例以及用量、乙腈的体积分数、样品加入量和温度对栀子苷分配行为的影响。 当温度为25 ℃时,栀子的乙腈/水（体积比1∶1）提取液中加入KCl与MgSO4组成的混盐（质量比2∶1）分相诱导剂后,栀子苷的萃取率达到81.63%,含量由分相前的3.05%提高至13.54%。     

铀-2-(3,5-二溴-2-吡啶偶氮)-5-二乙氨基苯酚-Triton X-100析相体系的研究及应用

本文研究了铀-2-(3,5-二溴-2-吡啶偶氨)-5-二乙氨基苯酚(3,5-diBr-PADAP)-Triton X-100析相光度体系,建立了矿石中微量铀的测定方法,在pH 7.5三乙醇胺-盐酸介质中,将胶束溶液在 95±1℃加热 1h.络合物即被Triton X-100相完全富集.络合物最大吸收峰位于565nm.摩尔吸光系数为1.02×10～5L·mol～(-1)·cm～(-1),铀含量在0～12μg/5mL服从比耳定律.采用TBP萃淋树脂分离干扰离子,测定矿石中微量铀,结果满意.     

采用溶胶-凝胶技术涂层的新型固相微萃取方法及其应用

将溶胶-凝胶技术应用于SPME固相涂层的制备,涂制的端羟基-聚二甲基硅氧烷固相涂层热稳定性好,萃取时间和解吸时间短,对极性化合物及非极性化合物均有较强的萃取富集能力。扫描电镜图显示涂层表面为多孔结构。采用该涂层的SPME方法在对环境样品的分析中获得了令人满意的效果。     

Phase Separation and Transport Behavior in La0. 67-x Smx Sr0.33 MnO3 System

The magnetic behavior and the transport behavior of La0.67-x Smx Sr0.33 MnO3 （x = 0. 00, 0. 10, 0. 20, 0. 30, 0. 40, 0. 50 and 0. 60 ） systems were studied through measuring the M-T curves, electron spin resonance （ ESR ） curves and ρ-T curves. The samples exhibit a long-range ferromagnetic order when x = 0. 00, 0. 10, a cluster-spin glass state when x = 0. 20 and 0. 30, and an anti-ferromagnetic state at low temperatures when x = 0. 40, 0. 50 and 0. 60. The samples of x = 0. 30 and 0.40 show phase separation at temperatures above Te. The transport behavior of the sample of x = 0. 60 becomes abnormal when the doping is high, and an insulator-metal transition occurs near To and then a metal-insulator transition occurs, which rarely appears in an ABO3 structure. It is concluded that the magnetic and electric behavior changes of the systems depend on the extra magnetism and lattice distortion effect induced by Sm doping.     

Synthesis and In Vitro Behavior of Organically Modified Silicate Containing Ca Ions

Organically modified silicates containing calcium ion have a potential to bond to bone via an apatite layer deposited on their surfaces in the body environment. In this study, we examined the relationship between apatite deposition and the microstructure of the organically modified silicates synthesized from tetraethoxysilane (TEOS) and poly (dimethylsiloxane) (PDMS) with a different amount of calcium nitrate tetrahydrate (Ca(NO₃)₂·4H₂O) and hydrochloric acid (HCl). Apatite deposition was evaluated in vitro using a simulated body fluid (Kokubo solution). Copolymerization was confirmed between TEOS and PDMS even if PDMS free from —SiOH termination are used as one of the starting materials. The porosity and Ca content incorporated in the structure depended on the amount of HCl, whereas analysis of ²⁹Si MAS NMR spectra indicates that it caused few effects on the local structure around Si atoms. Apatite-forming ability is enhanced by optimal amounts of HCl and Ca (NO₃)₂·4H₂O. The difference in apatite-forming ability among the hybrid gels was attributed to both Ca(II) contents in the structure and aggregation states of the Si—OH groups. Better bioactivity of the hybrid gels is achieved by the release of Ca(II) ions trapped in structure at gelation and the formation of hydrated silica rich in Si—OH.