溶胶—凝胶技术在分析化学中的应用进展

溶胶－凝胶技术是一种很有发展前途的材料制备方法，已在材料科学及有关的许多领域得到广泛重视。本文简要综述近年来溶胶－凝胶技术在色谱分析，光分析和电分析等分析化学领域中的应用。     

溶胶-凝胶法制备二氧化钛溶胶

以钛酸丁脂为前驱体,乙醇为溶剂,采用溶胶-凝胶法制备了二氧化钛(TiO2)溶胶.最佳制备条件为:钛酸丁脂29 mmol,n(水):n(钛酸丁脂)=5:1,n(乙醇):n(钛酸丁脂)=15:1,pH 3～4,聚乙烯醇2 mL,于室温剧烈搅拌下缓慢加料制得透明度较好,可长时间放置,粘度适于涂膜的TiO2溶胶.     

溶胶凝胶技术在化学及生物传感器领域中的应用

本文介绍了一种新的用于化学或生物传感器固定敏感试剂的溶胶凝胶技术,用此技术制成的传感器基质具有优异的光学特性和热力学,机械稳定性,且它形成的化学条件温和,尤其适用于包埋生物大分子。     

烷氧基硅烷溶胶-凝胶反应机理

利用烷氧基硅烷作为前驱体之一,进行溶胶-凝胶(sol-gel)反应制备无机氧化物和有机－无机杂化材料,近几十年来一直是一个研究热点。对烷氧基硅烷的sol-gel反应过程,特别是起始的水解和初步缩合过程已有较多的研究。本文综述了烷氧基硅烷的sol-gel反应机理研究的进展,并对未来发展提出了看法。     

溶胶-凝胶技术在电化学和生物传感器制备中的应用近况

对溶胶-凝胶技术在制备电化学和生物传感器中的应用近况(涉及年份主要在1992-2006年间)作了评述,内容主要集中在应用此技术包埋某些电化学活性物质或生物化学活性分子于其中而制备相关传感器的方法及其原理,在制备传感器过程中的影响因素以及此类传感器的分析应用。此外,对其发展趋势也作了简单的讨论(引用参考文献51篇)。     

溶胶-凝胶法制备氧化铝光学薄膜

氧化铝薄膜性能优异,具有较高的介电常数、高热导率、抗辐照能力强、抗碱离子渗透能力强以及在很宽的波长范围内透明等性能。因此,氧化铝薄膜广泛地应用于微电子器件、电致发光器件、光波导器件以及抗腐蚀涂层等众多领域[1]。特别是氧化铝光学薄膜具有高的抗激光损伤阈值[2],用     

溶胶-凝胶技术制备毛细管硅胶整体柱及其应用

采用溶胶-凝胶技术合成硅胶整体柱，研究了不同反应物配比对制备毛细管硅胶整体柱的影响，合成了具有高机械强度和化学稳定性的毛细管硅胶整体柱。通过十八烷基修饰得到反相固定相。考察了电渗流行为和电色谱性能。3种芳香胺和4种苯同系物可达到基线分离，柱效高达159000N／m。     

基于溶胶-凝胶固定技术的生物组织传感器

报道了一个制备生物组织传感器的新技术。将溶胶 凝胶与植物液汁按一定比例结合 ,使天然植物中的多酚氧化酶被固定于溶胶 凝胶中 ,将其滴涂于预先涂有一层Nafion膜的铂盘电极表面 ,构成带有Nafion 溶胶凝胶 植物液汁的复合修饰膜的生物传感器 ,用于测定神经递质多巴胺。采用循环伏安法和线性扫描伏安法考察了传感器的电化学特性 ,比较了不同植物品种及其不同部位组织的生物催化活性 ;研究了乙醇用量、水酯比、植物液汁用量等因素的影响 ;考察了Nafion膜的防干扰性能。采用差示脉冲伏安法对多巴胺进行定量分析 ,线性范围为 2× 10 -6～ 1× 10 -4mol/L ;检出限为 8.0× 10 -7mol/L。与传统的组织电极相比 ,本传感器具有一系列特点。     

掺杂荧光素的溶胶-凝胶膜的性质

溶胶-凝胶技术是制备材料的湿化学方法,由于设备简单,成本低,易于实现分子程度的性能复合且以溶胶-凝胶法制得的二氧化硅凝胶基质具有以下优点:(1)从紫外到可见波段内透明,且无光降解现象,适合于作光学(如光度、发光或荧光)检测器的基质;     

金属离子水化学-溶胶凝胶法制备固体催化材料的化学基础

简要介绍了作为溶胶凝胶法制备固体催化材料的化学基础的金属离子水化学进展.     

Mullite Fibre Mats by a Sol-Gel Spinning Technique

Fine grained, microcrystalline mullite (Al_4+2x Si_2–2x O_10–x) fibre mats with a web-like structure were fabricated by a sol-gel spinning technique using a multi-orifice spinneret. Points of contact in gel fibre mats helped in the formation of a web-like fibrous body having reasonable strength and very little dust formation after calcination. Strong and resilient fibres with diameters in the range 3–12 m were obtained by a single-step sol-gel method from spinnable sols devoid of organics as the binder aid. Crystallization of -alumina and mullite at about 900°C and 1250°C, respectively was confirmed by differential thermal analysis (DTA) and X-ray diffraction (XRD). Thermogravimetry (TG) indicated the removal of most of the volatiles at about 500°C accompanied by a weight loss of about 48%. Scanning electron microscopy (SEM) shows the presence of small grains (80–150 nm in size) in the fibres calcined at 1250°C. Fourier transformed infrared spectroscopy (FTIR) indicated the sequence of transformations taking place during heat-treatment of gel fibres at different temperatures. The individual fibres in the mats calcined at 1250°C exhibited a tensile strength of 1300–1600 MPa.     

纳米SnO的溶胶-凝胶法制备与电化学性能

以氯化亚锡、草酸和无水乙醇为原料，采用溶胶-凝胶法制备了纳米SnO粉末，并用热重-差热分析、X-射线衍射分析、透射电镜和扫描电镜等多种电化学方法对其进行了表征。结果表明，采用溶胶-凝胶法可以制备出粒度分布较集中，平均粒径在20 nm左右的纳米SnO粉末。该纳米SnO的可逆容量达到607 mAh·g^-1，经80次循环后平均每次循环的容量损失只有0.056%，说明纳米SnO是一种优秀的高容量锂离子电池负极材料。     

组合分析浅释

组合分析是为研、发新化学品(特别是新药)服务的,研、发新化学品历来遵循两条路线①是设计路线,即从主观思维出发,在经受客观检验的过程中进行不断修改,以求得主、客观的统一;②是筛选路线,即从客观出发,进行“神农尝百草”的寻找。这两条路线的缺点是明显的,旷日持久,宛如大海捞针,很可能徒劳无功,研、发的风险很大。     

A Study of PbTiO3 Crystallization in Pure and Composite Nanopowders Prepared by the Sol-Gel Technique

Summary.  In this investigation the crystallization of PbTiO₃ upon annealing of pure nanopowders and PbTiO₃–SiO₂ (1:1 v/v) nanocomposite powders prepared by the sol-gel technique was studied. Using X-ray diffraction phase analysis, the start of PbTiO₃ crystallization in pure PbTiO₃ powders was detected at 400°C. Distinct crystallization of PbTiO₃ in PbTiO₃–SiO₂ nanocomposites starts at 700°C, whereas SiO₂ remains amorphous. There are indications that an interface interaction between the PbTiO₃ and the SiO₂ phase plays an important role in hindering the crystallization of PbTiO₃. The particle size (size of coherently scattering regions) was estimated from the broadening of the X-ray diffraction line profiles. The average size of PbTiO₃ nanocrystallites increases with temperature and time of annealing, the influence of temperature being more significant than that of the annealing time. Differential scanning calorimetry confirmed the results of the X-ray diffraction with respect to the start of the crystallization. Laser beam scattering and scanning electron microscopy provided the statistical distribution of the grain size and the morphology of the powder grains, showing that each grain of the powders contains several nanocrystallites (coherently scattering regions). Received October 4, 2001. Accepted (revised) December 14, 2001     

溶胶凝胶溴离子选择电极的研制与应用

报道了一种以溶胶凝胶为载体的溴离子选择电极。电极信号响应线性范围为1 .0× 1 0 - 1～ 1 .0× 1 0 - 5mol/L,斜率为 5 7m V/pc;检出限为 2 .5× 1 0 - 6 mol/L。该电极响应快 ,体积小 ,稳定性和重现性好。电极用作测定溴离子浓度 ,结果令人满意     

A Generic Technique for Coating Doped Sol-Gel Films onto the Inside of Tubes for Use as Colorimetric Sensors

Sol-gel thin films have been doped with bromophenol blue and eriochrome cyanine RC for measuring pH and Cu⁺⁺ in solution respectively. The films were coated inside glass tubes by a novel method. Films doped with bromophenol blue responded to pH changes from pH 3 to 8. They were stable to variations in temperature from 20°C to 40°C. The sensing films have been subjected to leaching studies in different pH buffer solutions. Copper ions in solution have been measured to a minimum concentration of 0.6 ppm by eriochrome immobilised in sol-gel films. The interferences of other metal ions were also studied. Doped sol-gel films coated onto the inside of test tubes offer a simple, none-invasive, reusable and fast optical chemical sensing technique for the measurement of colour by spectroscopy or colorimetry.     

Room-Temperature Mirror Preparation Using Sol-Gel Chemistry and Laminar-Flow Coating Technique

The CEA/DAM megajoule-class pulsed Nd:glass laser devoted to Inertial Confinement Fusion (ICF) research will require 240 cavity-end mirrors. The approved laser design necessitates 42-cm × 46-cm × 9-cm highly-reflective (HR)-coated substrates representing more than 50 m² of coated area. Prototypes of these dielectric mirrors were prepared with interference quaterwave stacks of SiO₂ and ZrO₂-PVP (PolyVinylPyrrolidone) thin films starting from sol-gel colloidal suspensions (sols). Low refractive index material was based on nanosized silica particles and high refractive index coating solution was made of a composite system. The colloidal/polymeric ratio in the composite system has been optimized regarding refractive index value, laser damage threshold and chemical interactions have been studied using FT-IR spectroscopy. A deposition technique so-called Laminar Flow Coating (LFC) has been associated to sol-gel chemistry for HR laser damage-resistant sol-gel coating development. This novel coating method confirmed its main advantages compared to dipping or spinning processes: coating large flat square substrates at room temperature with small solution consumption, good thickness uniformity, weak edge-effects, induced stress-free coating, good optical properties and laser damage resistance fulfilling.     

Catalysis in Organic Solvents with Lipase Immobilized by Sol-Gel Technique

A series of immobilized lipases were obtained by sol-gel process, using silica prepolymers prepared from tetramethoxysilane, methyltrimethoxysilane, propyltrimethoxysilane and (3-aminopropyl)triethoxysilane. The activities of these biocatalysts were compared with the lipase adsorbed on poly(methylhydroxysiloxane) and encapsulated into a silicone rubber, lipase entrapped in nanoporous silica matrix and commercial sol-gel lipase. Model reactions were the esterification of stearic acid and Corey lactone bisalcohol (an intermediate of prostaglandin synthesis). The positive effect of hydrophobic-hydrophilic interface, created by the addition of organosilanes, on the activity of biocatalysts was partially reduced by decreasing specific surface of mesopores. Hydrophobic solvents increased the activity of the lipase entrapped in tetramethoxysilane–methyltrimethoxysilane prepolymer in the sequence acetone < toluene < benzene < decane < hexane. The activity of silicone rubber-encapsulated biocatalysts was proportional to polymer swelling in organic solvents (hexane > toluene > acetone).     

The Application of a Sol-Gel Technique to Preparation of a Heavy Metal Biosorbent from Yeast Cells

In this work we compared biosorbents obtained by encapsulation of polysaccharides, isolated from waste brewing biomass, in sol-gel derived silicates and an organic polymer. Biosorbents were prepared by mixing cross-linking-agents—organic or siliceous—with dried cells envelopes. Siliceous prepolymers were synthezised via transesterification and hydrolysis from tetraethoxysilane (TEOS) and methanol. Sorption of Cd2+, Cu2+ and Ag+ by biosorbent granules (0.25–0.6 mm) was examined in batch and in a packed column. The biosorbent prepared by interesterification of TEOS showed a 2–3 times higher intensity of sorption than the biosorbent cross-linked with epichlorohydrin (the most effective cross-linking organic agent) while the sorption capacity of both biosorbents was equal. The specific surface area of the silica matrix was 597 m2/g but only traces of metals were sequestered from solution with a concentration of Cd2+ of 50 mg/l. The biosorbent with a silica matrix is a heterogeneous material containing microporous matrix inclusions of thin cell walls. Its high sorption intensity and good mechanical strength will be useful in continuous metal uptake of low concentrations of metals.