白炭黑/聚氧化丙烯悬浮液的分子弛豫与流变行为

气相二氧化硅/聚醚低聚物悬浮液体系广泛应用于涂料、胶黏剂、锂离子电池、液体防弹衣等诸多领域.然而,聚醚与白炭黑界面相互作用复杂,所形成的界面吸附层显著影响悬浮液的流变行为,界面层结构与流变行为调控是长期困扰学术界和工业界的难题.本文工作详细研究了白炭黑/线形丙二醇低聚物(PPG)界面层结构与流变行为,考察了PPG分子量(0.4～4 kg/mol)的影响机制.研究发现,PPG分子量影响其在白炭黑附近的受限状态和悬浮液流变行为.分子量为0.4 kg/mol时,PPG通过端羟基与白炭黑表面硅羟基间氢键作用而形成较厚((1.0±0.2) nm)的玻璃化层,玻璃化层几何逾渗导致悬浮液在10 rad/s下呈现溶胶-凝胶转变;分子量为1～2 kg/mol的PPG在白炭黑粒子表面形成较薄((0.8±0.1) nm)的玻璃化层,分子量为3～4 kg/mol的PPG则在白炭黑粒子表面形成受限层,悬浮液在10 rad/s下呈溶胶行为.玻璃化层几何逾渗和悬浮液溶胶-凝胶转变之间的关系说明,界面层分子受限程度和流变行为均受PPG羟基密度及其与白炭黑界面相互作用的影响.     

锌-钬共掺杂无机抗菌材料的制备及性能研究

采用溶胶-凝胶法制备了一种新型无机抗菌材料--锌-钬抗菌白炭黑。通过单因素实验和响应曲面法优化,得到了最优制备条件为:锌浓度0.711 mol·L^-1,钬浓度0.5 mmol·L^-1及反应时间65 min。获得了分散性好、粒度较小、抗菌性能良好的复合抗菌材料。通过SEM,EDS,FTIR,粒径检测和抗菌检测等手段对锌-钬抗菌白炭黑进行了表征。结果表明:锌-钬抗菌白炭黑结构蓬松,平均粒径为28.948μm,且锌离子和钬离子的添加对载体白炭黑的结构基本没有影响,其抗菌率可达83.41%。     

氧氯化锆前驱体离子交换法制备氧化锆溶胶

以氧氯化锆为原料,采用离子交换法制备氧化锆溶胶.考察了制备过程中pH值对溶胶稳定性的影响,探讨了溶胶形成机理.应用TEM对所制溶胶胶粒形貌、粒径进行了分析,采用TG、DTA、XRD、FTIR等测试手段分析了干凝胶的热稳定性和结构变化.结果表明,离子交换法是制备氧化锆溶胶的简单、有效方法,所制的溶胶无色透明,稳定性好.氧化锆干凝胶在400□～600□为四方相,从700□开始有少量单斜相出现.     

改进溶胶-凝胶法固定酶结构剖析及在苯酚光化学传感器中的应用

通过光学显微镜比较了用密闭老化法和浸涂法制备的溶胶凝胶膜的表面状态,从实验上证实了用密闭老化法制备的溶胶凝胶膜不会破裂;并用透射电子显微镜观察了包埋辣根过氧化物酶的溶胶凝胶膜的内部结构.结果表明,酶固定于溶胶凝胶中后,与在溶液中一样,呈均匀分布且不易流失.此敏感膜可用于制备基于化学发光强度减弱的苯酚光化学传感器;用竞争反应的原理讨论了响应机理.     

无机物的光学和电化学传感器

本文讨论将溶胶凝胶作为一种基质来发展独特的传感策略．溶胶凝胶为传感基质的制备和发展提供了无限空间,这种空间得益于基质物理性质的多样性,可以通过改变一些传感器已知的制备条件和合成技术来实现．我们在对传感需求的认真考虑和研究的基础上,开发出了用于一些分析物的新的检测方法,同时发展了它们的应用．溶胶凝胶被用来监测浓强酸（[H^＋]=1～11M）,浓强碱（[OH^-]：1～10M）及采用双传感方法来测定混合溶剂／溶质系统．本文还讨论了使用配体嫁接的块状溶胶凝胶对金属离子进行光学测定．最后介绍了用电化学法和溶胶凝胶修饰的电极来测定六价铬的方法．     

冷气溶胶灭火剂用NaHCO3/白炭黑复合粒子的制备

气溶胶;碳酸氢钠;干粉灭火剂;冷气溶胶灭火剂用NaHCO3/白炭黑复合粒子的制备     

改进溶胶—凝胶法固定酶结构剖析及在苯酚光化学传感器？…

通过光学显微镜比较了用密闭老化法和浸涂法制备的溶胶－凝胶膜的表面状态,从实验上证实了用密闭老化法制备的溶胶－凝胶膜不会破裂,并用透射电子显微镜了包埋根过氧化物酶的溶胶－凝胶膜的内部结构。     

Al2O3-PLOT毛细管色谱柱的溶胶-凝胶法制备

首次将溶胶-凝胶法用于制备Al2O3-PLOT毛细管色谱柱.采用正硅酸乙酯、稀盐酸以及氧化铝的乙醇悬浮液组成的溶胶体系,高压动态法涂敷石英毛细管,然后通过高温凝胶反应固定Al2O3涂层,再用无机盐溶液淋洗灭活得到成品.考察制备过程的重复性,表明溶胶-凝胶法制备Al2O3-PLOT色谱柱简单易行,重复性好;对色谱柱性能进行评价,18组分C1 ～C5烃类标准气完全基线分离,环丙烷和丙烯的分离度为1.55 ～1.65,甲烷和正丁烷保留时间变化范围分别小于0.5%和1%,色谱柱的耐温性和稳定性显著提高.     

γ-Al_2O_3复合膜的制备及顶膜完整性检验

用工业产品PURSAL SB粉代替醇盐制备γ-AlOOH溶胶,准弹性光散射实验表明,溶胶粒径分布集中在35nm左右,由该溶胶而得到的γ-Al_2O_3非担载膜的孔径分布很窄,平均孔径为4.8nm,比表面积为320m~2/g.用该方法制备的γ-AlOOH溶胶经两次浸涂、干燥、焙烧循环,能在多孔α-Al_2O_3底膜上形成完整的γ-Al_2O_3顶膜,用SEM电子显微镜没有观察到有裂缝或针孔的形成,气体渗透实验结果也证实了γ-Al_2O_3的顶膜是完整的。     

GdAlO_3:Er~(3+),Yb~(3+)荧光粉的制备与上转换发光性能

采用共沉淀、溶胶-凝胶和固相反应法制备了GdAlO3:Er3+,Yb3+荧光粉.借助X射线衍射、扫描电子显微镜、傅里叶变换红外光谱、N2-吸附、吸收光谱和荧光光谱等手段研究了不同方法制备的GdAlO3:Er3+,Yb3+荧光粉结构、形貌、表面基团和光吸收及上转换发光性能.结果表明:用共沉淀法比固相反应法和溶胶-凝胶法可以在更温和的条件下制得纯相GdAlO3:Er3+,Yb3+荧光粉,用共沉淀法和溶胶-凝胶法制备的GdAlO3:Er3+,Yb3+荧光粉颗粒都在纳米尺寸,溶胶-凝胶法制得的样品存在相对严重的颗粒团聚现象,而用固相反应法制备的荧光粉为微米级颗粒.GdAlO3:Er3+,Yb3+荧光粉在980 nm激发的上转换发射光谱包含波长为524和546 nm的绿光与659 nm的红光,且三种方法制备的样品绿光发射强度都显著高于红光.不同方法制备的荧光粉上转换发光强度和红光/绿光强度比相差较大,共沉淀法制备的样品上转换发光强度要显著高于固相法以及溶胶-凝胶法制备的样品,而溶胶-凝胶法制备的样品发光中红光/绿光相对强度比最高.红外光谱显示,不同方法制备的GdAlO3:Er3+,Yb3+荧光粉表面OH-、CO32-及CO2官能团含量不同,溶胶-凝胶法制备的样品要明显高些.基于红外光谱、不同Er3+和Yb3+离子掺杂浓度及不同激光功率上转换发光的结果,对Er3+和Yb3+之间的能量传递过程及不同方法制备荧光粉的上转换发光性能进行了讨论.     

Synthesis of micrometer-sized silica-stabilized polystyrene latex particles

Micrometer-sized silica-stabilized polystyrene latexes have been readily prepared by alcoholic dispersion polymerization using a 13 or 22 nm commercial alcoholic silica sol as the sole stabilizing agent. These resulting surfactant-free polystyrene particles have relatively narrow particle size distributions and contain surprisingly low levels of silica (相似文献   

Deposition of silica thin films formed by sol–gel method

Deposition of silica thin films on silicon wafer was investigated by in situ mass measurements with a microbalance configured for dip coating. Mass change was recorded with respect to deposition time when the substrate was fully immersed in the silica sol. Mass gain during deposition was higher than predicted from monolayer coverage of silica nano particles. This implied that deposition was facilitated by gelling of the nanoparticles on the substrate. The rate of deposition was enhanced by increasing the particle concentration in the sol and by decreasing the particle size from 12 to 5 nm. Increasing the salt concentration of the silica sol at constant pH enhanced the deposition of the silica particles. Reducing the pH of the sol from 10 to 6 decreased the deposition rate due to aggregation of the primary silica particles.     

Corrosion protection enhancement effect by mixed silica nanoparticles of different sizes incorporated in a sol–gel silica film

We demonstrate an enhancement of corrosion protection by sol–gel silica film including mixed silica nanoparticles of 10 and 50 nm. Low-temperature silica films were prepared by sol–gel dip-coating method, followed by a thermal annealing at 200 °C. Importantly, film with mixed particles exhibits lower corrosion current density and slower loss of film resistance during the immersion in electrolyte solution, showing an improved corrosion protection over the film with 50 nm particles. The improved corrosion protectability of the mixed particles comes from the suppressed diffusion of ionic species by a close packing of 10 nm particles.     

Sol–gel preparation of double-layer tri-wavelength antireflective coating

Double-layer tri-wavelength antireflective (AR) coating effective simultaneously at 351, 527 and 1,053?nm has been designed and prepared by the sol?Cgel process. The refractive index and film thickness of bottom layer and up layer are 1.27 and 113?nm, and 1.17 and 245?nm, respectively. The bottom layer with refractive index of 1.27 was prepared from a mixture of acid-catalyzed and base-catalyzed silica sols, and the up layer with refractive index of 1.17 was prepared from polypropylene oxide modified silica sol. It was found that the addition of polypropylene oxide into the sol significantly decreased the refractive index and increased the hydrophobicity of the AR coating. The obtained tri-wavelength AR coating gives very high transmittance of 99.7, 99.1 and 98.0?% at 351, 527 and 1,053?nm, simultaneously.     

Efficient synthesis of poly(2-vinylpyridine)-silica colloidal nanocomposite particles using a cationic azo initiator

Colloidal poly(2-vinylpyridine)-silica nanocomposite particles can be efficiently prepared by emulsion polymerization at 60 degrees C using a commercial 20 nm aqueous silica sol as the sole stabilizing agent. Unlike previously reported colloidal nanocomposite syntheses, transmission electron microscopy studies indicate very high silica aggregation efficiencies (88-99%). The key to success is simply the selection of a suitable cationic azo initiator. In contrast, the use of an anionic persulfate initiator leads to substantial contamination of the nanocomposite particles with excess silica sol. The cationic azo initiator is electrostatically adsorbed onto the anionic silica sol at submonolayer coverage, which suggests that surface polymerization may be important for successful nanocomposite formation. Moreover, the 2-vinylpyridine can be partially replaced with either styrene or methacrylic comonomers to produce a range of copolymer-silica nanocomposite particles. The poly(2-vinylpyridine)-silica nanocomposite particles have a well-defined core-shell morphology, with poly(2-vinylpyridine) cores and silica shells; mean diameters typically vary from 180 to 220 nm, and mean silica contents range from 27 to 35% by mass.     

Preparation and characteristics of spinnable sol and continuous mullite fibers with nano silica addition

The spinning precursor sols for the continuous mullite-based fibers were prepared by adding nano-silica to substitute part of silica sol. The effect of SiO₂ nanoparticles on the particle evolution models, polymerization degree and solid content of the sol,and the spinning length and sintering behavior of the fibers was investigated. The results were shown that the addition of nano silica enhanced the polymerization degree and extended the spinnable range of the sol. The appropriate polymerization degree (B value) for this sol system was 1.885–2.145. The grain diameter decreased from 39.6 to 25.9 nm with increasing the nano-silica content to 20 %, and then, it increased to 41.2 nm with increasing the nano-silica content to 100 %. The appropriate content of nano-silica powders would reduce the grain diameter. However, it had no influence on the linear growth model, homogeneity and solid content of the precursor sol.     

Effect of precursors of mesoporous silica on the adsorption properties of a ceramic material

Nitrogen low-temperature adsorption-desorption is employed to investigate the adsorption and textural properties of a ceramic material coated with silica, which is produced by the sol-gel method from oxide and alkoxide precursors. It is shown that a mesoporous silica coating with a thickness of ≈300–400 nm and a denser layer with a thickness of 13–34 nm are formed from deionized silica sol and hydrolyzed tetraethoxysilane, respectively.     

静电纺丝法制备硫酸化的二氧化锆/二氧化硅复合纤维

将电纺丝技术与溶胶-凝胶技术相结合, 制备了SZ粒子分布于SiO2纤维外壁的硫酸化的二氧化锆/二氧化硅复合纤维. 与常见的SZ复合催化剂相比, 采用SiO2纤维负载SZ不仅可以解决粉体材料带来的难以与反应体系分离等弊病, 同时功能粒子SZ分布与纤维外壁的结构也提高了功能粒子的利用率.     

Preparation and characterization of polypyrrole-silica colloidal nanocomposites in water-methanol mixtures

The effect of methanol cosolvent on the synthesis of polypyrrole-silica colloidal nanocomposites using ultrafine silica sols in combination with both FeCl3 and APS oxidants has been investigated. Two protocols were evaluated: the addition of methanol to an aqueous silica sol and the addition of water to a methanolic silica sol. The latter protocol proved to be more robust, since it allowed colloidally stable dispersions to be prepared at higher methanol content (up to 50 vol% using the APS oxidant). This allowed greater control over the particle size of the nanocomposite particles. In general, the spectroscopic data, the particle size range, silica contents and electrical conductivities of these nanocomposites were similar to those reported earlier for purely aqueous formulations. Polypyrrole contents ranged from 49 to 71% by mass and particle diameters varied from around 160 to 360 nm. In terms of colloid stability, the APS oxidant was preferred for nanocomposite syntheses in the presence of methanol. However, the FeCl3 oxidant generally gave higher conductivities and narrower size distributions under comparable conditions. HF etching experiments combined with transmission electron microscopy studies indicated that, to a first approximation, these nanocomposite particles had core-shell morphologies, with a hydrophobic polypyrrole core and a hydrophilic silica shell that compose approximately one monolayer of silica sol particles. Finally, aqueous electrophoresis measurements suggested that the polypyrrole-silica nanocomposites were silica-rich and that the methanolic silica sol was more hydrophobic (lower surface charge density) than the aqueous silica sol.     

Microstructure evolution in Stöber-type silica nanoparticles and their in vitro apatite deposition

Prepared via Stöber-type sol–gel routes were three types of silica particles of <1 μm in size: pure silica, Ca-involving silica, and chitosan/alginate-coated silica with a polymershell-silica core structure. Calcium ions were impregnated in the organic layers of the polymer-coated silica particle. The sol–gel procedure was applied to tetraethoxysilane dissolved in an ethanol/water mixture, while Ca–silica was derived from CaCl₂-containing ethanol/water solutions. Scanning and transmission electron micrograph analyses indicated that those silica particles consisted of ~10 nm primary particles, the Ca–silica particles (~500 nm) were larger than the Ca-free ones (~200 nm) and that their size increased with the Ca concentration in the precursor solutions. From ¹H- and ²⁹Si- magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra and ²⁹Si cross-polarization NMR spectra, the mechanism of primary particle agglomeration and degradation of the secondary particles in saline were discussed in terms of the content of H₂O molecules and >Si–OH as well as hydrogen bonding interactions among them. In addition, the Ca–silica and core-shell silica deposited apatite in Kokubo’s simulated body fluid. Thus, the present Ca–silica and polymer-coated silica particles were suggested to be applicable to injectable bone fillers for bone generation.