Encapsulation of Water-Soluble Dye in Spherical Sol-Gel Silica Matrices

The water-soluble, Lithol rubine B, dye was encapsulated into silica microspheres matrices. Encapsulation has been carried out by sol-gel process of W/O microemulsions formed from sodium silicate and dye aqueous solution in cyclohexane medium. The average particle size could be tailored from 1–10 m, depending on the processing parameter such as homogenizing speed in the formation of W/O emulsion, the weight ratio of water to oil, and concentration of sodium silicate solution, etc. The pore size of dye-doped silica microspheres was measured by nitrogen adsorption-desorption isotherms. The leaching behavior of dye entrapped in silica matrices was investigated by UV/VIS and UV diffuse reflectance spectroscopy for the extract and solid powders after immersion for 24 h in water. The doping of GPTS (3-glycidoxypropyltrimethoxysilane) in sodium silicate and dye mixture solution greatly enhanced the stability against leaching of the dye. It was ascribed that GPTS serves simultaneously as an intermediate for the chemical bonding between the dye and silica, and as an agent for the formation of hybrid sol responsible for the shrinkage of pore size.     

Improvement in the Leaching Behavior of Dye-Doped Modified Silica Layers Coated onto Paper or Textiles

Leaching stability is important when refining paper or textile surfaces with sol-gel silica layers that contain incorporated dyes or other components. First studies show a simultaneous increase in dye and Si concentration in the wash-out solution, indicating that the gradual dissolution of the complete composite layer plays an important role in the leaching process. The leaching stability of silica layers containing incorporated model dyes Aniline Yellow and Acid Orange 10 on different flexible substrates (cellulose paper, polyamide and polyester fabrics) could be improved in a number of different ways: (i) pretreating the substrate with coupling agents such as epoxyalkyl-silanes, (ii) fixing the dye within the silica layer by mixing it with alumina or alkylammonium compounds, and (iii) chemically fixing the dye by bonding it covalently to the silica matrix.     

超细二氧化硅粉体的制备

超细二氧化硅粉体的制备李中军＊刘长让王雪清ａ赵秦生（郑州大学化学化工学院，物理系ａ郑州４５００５２）（中南工业大学长沙）关键词溶胶－凝胶法，ＳｉＯ２超细粉，粉体制备１９９７－０９－２３收稿，１９９８－０３－０２修回溶胶－凝胶工艺是液相法制备超细ＳｉＯ...     

A New ESIPT Fluorescent Dye-Doped Silica Aerogel

Summary: A silyl-functionalized benzazole dye, fluorescent by excited state intramolecular proton transfer (ESIPT) mechanism, was synthesized by reacting 2-(2′-hydroxyphenyl)benzoxazole with 3-(triethoxysilyl)propyl isocyanate. The fluorescent silica gel was prepared by the addition of a solution of 2-propanol and the fluorescent dye after the gelation time. The monolithic aerogel was obtained via supercritical CO₂ drying of the fluorescent gel. The resulting aerogel is transparent in the visible light and fluorescent in the blue-green region under UV radiation.     

Experimental Study on Viscosity of Colloidal Silica in Aqueous Electrolytic Solutions

The relative viscosity of colloidal silica dispersion in aqueous electrolytic solutions as the function of volume fraction of dry particles in the solutions has been experimentally determined in this work, in order to study the effects of pH and electrolytes (Na₂SO₄ and AlCl₃) on the hydration of the silica surfaces in the solutions. The results have shown that the maximum relative viscosity of the silica dispersion and the strongest hydration of the silica in aqueous solutions appeared at neutral pH, while the stronger the acidity and the alkalinity of the aqueous solution, the weaker the hydration. In the presence of the electrolytes (Na₂SO₄ and AlCl₃), the relative viscosity of the silica dispersion reduced and the hydration of the silica in aqueous solutions became weak. The higher the concentration of the electrolytes, the weaker the hydration, indicating that the destabilization of the colloidal silica dispersion in aqueous solutions might be realized through adding the high-valence electrolytes to weaken the hydration of the particle surfaces (hydration forces between the particles). Also, it has been shown that the negative zeta potentials of the colloidal silica in aqueous solutions greatly reduced in the presence of the electrolytes. Therefore, the high-valence electrolytes (Na₂SO₄ and AlCl₃) as the coagulant of colloidal silica in aqueous solutions might be originated from that the presence of the electrolytes simultaneously reduces the electrical double layer repulsive force and the hydration repulsive forces between the particles in aqueous solutions.     

Dye-Doped Silica Nanoparticles for Enhanced ECL-Based Immunoassay Analytical Performance

The combination of highly sensitive techniques such as electrochemiluminescence (ECL) with nanotechnology sparked new analytical applications, in particular for immunoassay-based detection systems. In this context, nanomaterials, particularly dye-doped silica nanoparticles (DDSNPs) are of high interest, since they can offer several advantages in terms of sensitivity and performance. In this work we synthesized two sets of monodispersed and biotinylated [Ru(bpy)₃]²⁺-doped silica nanoparticles, named bio-Triton@RuNP and bio-Igepal@RuNP, obtained following the reverse microemulsion method using two different types of nonionic surfactants. Controlling the synthetic procedures, we were able to obtain nanoparticles (NPs) offering highly intense signal, using tri-n-propylamine (TPrA) as coreactant, with bio-Triton@RuNps being more efficient than bio-Igepal@RuNP.     

Production of Colourful Pigments Consisting of Amorphous Arrays of Silica Particles

It is desirable to produce colourful pigments that have anti‐fading properties and are environmentally friendly. In this Concept, we describe recently developed pigments that exhibit such characteristics. The pigments consist of amorphous arrays of submicron silica particles, and they exhibit saturated and angle‐independent structural colours. Variously coloured pigments can be produced by changing the size of the particles, and the saturation of the colour can be controlled by incorporating small amounts of black particles. We review a simple analysis that is useful for interpreting the angular independence of the structural colours and discuss the remaining tasks that must be accomplished for the realistic application of these pigments.     

UV-Induced Formation of [Fe(bpy)3]2+ Complex and its Confinement into Silica Fine Particles

Silica fine particles in a single or sub-micrometer regime, containing FeCl₃ and 2,2-bipyridine (bpy), were prepared by utilizing reverse micellar method. Formation of tris-bpy iron(II) ([Fe(bpy)₃]²⁺) complex was induced in the silica fine particles by UV irradiation at 365 nm. The starting micellar solution was obtained by an injection of 0.04 cm³ HCl aqueous solution into 5 cm³ tetraethyl orthosilicate (TEOS)/cyclohexane (2 cm³/3 cm³) mixed solution containing 4–14 vol% of nonionic surfactant, polyoxyethylene(5) nonylphenyl ether (NP-5). Size of the silica particles was regulated by the concentration of NP-5.     

气相SiO2在不同pH值介质中的分散特性

以激光动态光散射法考察了气相SiO2在不同pH值的H2SO4和NaOH介质中的分散平均水化粒径与表面Zeta电位及二者间的关系。 Zeta电位数据表明，气相SiO2在水中分散的表面硅羟基的等电点(IEP)和滴定终点(TE)的pH值分别为pH(IEP)=2.09和pH(TE)=7.47，利用滴定终点pH (TE)给出了一种简单的气相SiO2表面Si-OH浓度的测定方法。 分散相粒径数据显示，在等电点和滴定终点之间，气相SiO2在水中的分散粒子的粒径能够稳定在230 nm附近；在H2SO4介质中，当pH＜pH(IEP)时，随着H2SO4浓度的增大，体系中的分散粒子发生聚结而使表观粒径增大；在NaOH介质中，当pH＞pH(TE)时，随着NaOH浓度的增大，分散相的表观水化粒径降低，表明NaOH的加入有利于气相SiO2的分散。     

Synthesis of Nano Silica Particles for Polishing Prepared by Sol–Gel Method

In order to produce an excellent abrasive, a fabrication method for cocoon shaped silica particles has been studied. The particles are prepared from TMOS, water, ammonia and methanol by a sol–gel method. The method is to add the methanol solution of TMOS at a constant supply rate to a mixture of water, ammonia and methanol. Effects of various reaction conditions such as temperatures, supply rates of TMOS, and amounts of TMOS are studied on the diameter and shape of the particles. The diameter and shape are resulted in depending strongly on temperatures. High temperature makes particles with the high aspect ratio and the small diameter. And the mechanism of forming the cocoon shaped particle is also discussed. It is concluded that the primary particles are generated at the beginning stage of reaction and two of them become the cocoon shaped particle. For the polishing efficiency, particles have high polishing efficiency with the diameter between 40 nm and 210 nm. As a result, best diameter of particles for abrasive is 40–100 nm with respect to polishing efficiency and surface finish.     

复合SiO2粒子涂膜表面结构及超疏水性能

采用溶胶-凝胶法制备不同粒径SiO₂粒子，通过表面改性得到不同形状复合粒子，并利用氟硅氧烷的表面自组装功能制备了具有“荷叶效应”的超疏水涂膜。通过原子力显微镜、扫描电镜和水接触角的测试对膜结构及性能进行了表征，探讨了SiO₂粒子的粒径和形状与表面微观结构、表面粗糙度和表面疏水性能的关系。结果表明含单一粒径粒子涂膜表面水接触角符合Wenzel模型，而复合粒子构成了符合Cassie模型的非均相界面;单纯的粗糙度因子不能反映水接触角的变化，复合粒子在膜表面的无规则排列赋予涂膜表面不同等级的粗糙度，使得水滴与涂膜表面接触时能够形成高的空气捕捉率和较小的粗糙度因子;其与在涂膜表面能形成自组装分子膜的氟硅氧烷共同作用赋予了涂膜超疏水性能，而这种超疏水性能与复合粒子的粒径大小和形状基本无关。     

水溶性染料在LaCoO3体系中的光催化降解

采用柠檬酸络合法合成了粒径为20－30nm和LsCoO3复合氧化物，并以其为光催化剂在荧光汞灯及太阳光照射下进行不同结构水溶性染料的降解脱色实验，结果表明，LaCoO3在较强的光催化活性，LaCoO3有较强的光催化活性，经光声光谱，XPS等测试分析知其活性主要与Co^3 离子的d电子结构、Co-O结合能及表面氧空位等因素有关。     

气相二氧化硅/季铵Gemini表面活性剂稳定的泡沫体系

以zeta电位法研究了季铵Gemini表面活性剂亚甲基-α, ω-双(十二烷基二甲基溴化铵) (12-s-12, s=2, 6)在水溶液中修饰气相二氧化硅(F-SiO₂)粒子。这些粒子随表面活性剂浓度C增加经历了表面从原先的亲水到疏水再重新亲水的改变,其中疏水粒子可以自发吸附在气泡液膜中,从而很好地稳定泡沫。重新亲水的粒子脱附出液膜,仅留下表面活性剂稳定气泡。强的液膜弹性对应于稳定的泡沫。联接链长度影响了Gemini在F-SiO₂粒子表面的吸附,因而也影响了液膜的弹性和对泡沫的稳定。超短s=2联接链的12-2-12由于反离子解离不完全而带有较少的正电荷,在粒子表面的初始吸附弱于12-6-12,但因此减少了吸附分子头基间的静电排斥,可以形成更致密的吸附层。由于12-2-12本身比12-6-12具有更强的界面吸附能力,F-SiO₂粒子和12-2-12的协同作用可以更好地稳定泡沫体系。     

Synthesis of Nanoscale Shell-core Titania Coated Silica Particles in the Presence of Polyether Polyamine and the Phase Transition

IntroductionTitanium dioxide with the rutile or the anatasestructure as,in principle,a white pigmentis widelyused as paints and plastic additives because of itshigh refractive index,oil adsorption,chemical orthermal stability[1— 4 ] .The most common manu- fac-ture of this material is based on the digestion of theore ilmenite(Fe O· Ti O) with sulfuric acid,fol-lowed by hydrolyzing the solution of titanium ionsand the calcination of the hydrous titanium ox-ides[5] .Another industrial prepara…     

Preparation of Spherical Hydrous Silica Oxide Particles under Acidic Condition via Sol-Gel Processing

Preparation of spherical hydrous silica oxide particles via sol-gel processing was rarely reported. In this study, spherical silica particles were obtained in TEOS/AcOEt/AcOH 50% aq. system. The combination of AcOEt and AcOH 50% aq. widened the spherical particle-forming region. Their size ranged from some ten micrometers to some hundreds micrometers. Hydrophilic molecules or powders like Rhodamine 6G and phosphorescent powders were encapsulated in the spherical particles.     

阳离子型聚氨酯-脲-胺在二氧化硅水溶胶听吸咐行为

研究了水溶性阳离子聚氨酯-脲-胺乙酸盐在球形、单分散的纳米二氧化硅水分 散注保的吸附行为。PUUA分子链在烯溶液中呈较舒展的构象，分子尺寸小于纳米氧 化硅的粒径。PUUA通过van der Waals作用力和氢键吸附在氧化硅表面。在稳喧吸 附后，等温吸附线呈线性上升，且没有极限值。吸附量随纳米氧化硅粒径的增大、 胶粒表面电荷的减少和电解质乙酸钢加入量的变化均以相同的斜率线性下降。 PUUA分子量增加，吸附量增加，且分子量大的PUUA优先吸附于氧化硅胶粒表面，静 电吸引是PUUA吸附至氧化硅溶胶粒表面的主要作用力。PUUA在氧化硅胶粒上的吸咐 使体系表现粘度下降，敏化作用使体系呈假塑性，而保护作用使体系呈胀流型。     

Silica Coating on Colloidal Maghemite Particles

Maghemite colloidal particles are coated with a silica layer using a silicon alkoxide as silica precursor. The coating process is studied by electrophoresis, quasi-elastic light scattering, nitrogen adsorption, and infrared spectrometry analyses. The conditions of complete coverage of the iron oxide particles by silica and the nature of the maghemite–silica interface are discussed.     

Synthesis of Submicron-Sized Titania-Coated Silica Particles with a Sol-Gel Method and Their Application to Colloidal Photonic Crystals

A previously proposed method for preparing monodispersed titania particles was extended to preparation of titania-coated silica spherical particles. The core silica particles with an average size of 264 nm were prepared with Stöber method. The titania-coating was performed in ethanol/acetonitrile solvent in the presence of silica particles by a sol-gel method with the use of titanium tetraisopropoxide (TTIP) and methylamine (MA) catalyst. Average size of the silica-titania particles decreased from 457 to 292 nm with an increase in concentration of silica particles. Coefficient of variation for the particle size was less than 5%. Colloidal crystals could be fabricated with a dip-coating technique and a sedimentation process, respectively. Measurements of reflectance revealed peaks based on the Bragg diffraction. Those peaks red-shifted with an increase in titania shell thickness because of a high refractive index of titania. Annealing at high temperature transformed crystal structure of titania shell from amorphous to anatase (500°C) and rutile (1000°C), which led to red-shift of reflection peak because of an increase in refractive index of titania due to the crystallization.     

Encapsulation of Organic Pigment Particles with Silica via Sol-Gel Process

This paper presented a novel preparation method of silica coated organic pigment. In this approach, the surfaces of the organic pigment were first orderly modified by poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC), then coated by silica via sol-gel process of tetraethylorthosilicate (TEOS). The results showed that PVP, pH value, water and TEOS contents had significant influence on the morphology of the silica encapsulated organic pigment. Organic pigments coated silica by this approach could scatter UV ray with wavelength less than 270 nm, and this scattering property increased with more silica coated.     

由硅溶胶生长单分散颗粒的研究

针对现行单分散二氧化硅颗粒制备方法的粒径预见性差、步骤繁琐、收率低等问题，研究了一种用硅溶胶作为种子，在氨、水和乙醇的混合溶液中通过水解正硅酸乙酯（ＴＥＯＳ）生长出单分散颗粒的简便方法。该方法仅在初始的悬浮液中滴加ＴＥＯＳ即可使种子正常生长，无须补充氨水以修正体系浓度的变化。最终的分散相浓度可达１０％（质量分数）。可选择生长的粒径范围在１微米以内并可精确控制。所得颗粒粒径分布偏差于Ｓｔｏｂｅｒ方法