基于棒状介孔SiO_2剪切增稠流体的流变行为

以三嵌段共聚物聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO,P123)为模板剂,采用溶胶-凝胶法合成了介孔SiO_2-P123复合物,经煅烧除去P123得到不同长径比的棒状介孔SiO_2粒子,将其分散于聚乙二醇(PEG)中制成剪切增稠流体(STF),利用旋转流变仪对STF的流变性能进行了表征。结果表明:在稳态条件下,STF的剪切增稠效应随介孔SiO_2质量分数的增加而增强,随介孔SiO_2粒子长径比的增加而减弱;在动态条件下,STF的剪切增稠效应随介孔SiO_2质量分数的增加而减弱,随介孔SiO_2粒子长径比的增加而增强。     

侧链含8-羟基喹啉铝配合物的聚苯乙烯的合成与发光性能研究

通过高分子反应法研究制备了高分子化的8-羟基喹啉铝发光材料.首先使用自制的氯甲基化试剂1,4-二氯甲氧基丁烷(BCMB),制备了5-氯甲基-8-羟基喹啉(CHQ);通过聚苯乙烯(PS)与CHQ之间的Friedel-Crafts烷基化反应,制得侧链键合有8-羟基喹啉(HQ)的改性聚苯乙烯HQ-PS;再使HQ-PS与二配体...     

三维有序大孔Fe_2SiO_4/SiO_2@C锂离子电池负极纳米玻璃陶瓷-碳复合材料制备及电化学性能

以聚苯乙烯(PS)胶晶作为铸模,采用纳米铸造工艺及后续煅烧的方法合成了三维有序大孔Fe_2SiO_4/SiO_2@C纳米玻璃陶瓷锂离子电池负极材料。溶胶-凝胶工艺产生的凝胶在650℃氩气氛炉中煅烧后,Fe_2SiO_4纳米晶体从含铁元素的SiO_2基玻璃中结晶析出,形成由Fe_2SiO_4纳米晶体、铁离子(Fe3+)修饰的玻璃态SiO_2和非晶碳组成的三维有序大孔纳米玻璃陶瓷。在50 m A·g~(-1)电流密度下进行充放电时,其放电容量可达450 m Ah·g~(-1)以上,电流密度增加到250 m A·g~(-1)时可逆放电容量仍旧稳定地保持在260 m Ah·g~(-1),而具有同样有序大孔结构和含碳量的非晶态SiO_2@C材料的放电比容量在50 m A·g~(-1)电流密度时仅为15 m Ah·g~(-1)。这些结果表明,Fe_2SiO_4纳米晶体及Fe~(3+)有助于SiO_2基玻璃陶瓷实现可逆储锂过程。     

氯仿萃取8-羟基喹啉荧光法测定天然水中的总单核铝和酸溶态铝

采用氯仿萃取８－羟基喹啉荧光光度法（８－ＨＱ－ＣＬ－ＭＦ）测定了天然水样中的总单核铝和酸溶态铝含量,与Ｄｒｉｓｃｏｌｌ的甲基异丁基酮萃取８－羟基喹啉－石墨炉原子吸收法（８－ＨＱ－ＭＩＢＫ－ＧＦ／ＡＡＳ）法进行了比较,结果一致。本法具有取样量小,检测快捷,灵敏度高,重现性好等突出优点,合适于天然水中的总单核铝和酸溶态铝的分析。研究了滤膜过渡,酸消化以及紫外酸消化对天然水中铝形态测定的影响。     

羟基铝溶液及铝交联蒙脱土的研究

本文用(27)~Al NMR法和8-羟基喹啉萃取法分别研究了羟基铝溶液中十三聚铝含量的变化规律,还用X-射线衍射法研究了铝交联蒙脱土d_(001)的变化。研究结果表明,铝离子的聚合情况主要由羟铝比决定,而浓度影响不大。随着羟铝比的增加,溶液中单核铝离子含量减少,十三聚铝离子相对含量增加,所得铝交联蒙脱土的d_(001)也随之增大。参照这些变化规律、控制羟基铝溶液的组成,可以制备各种层柱状铝交联蒙脱土复合物。     

手性有序无机介孔硅用作气相色谱固定相

手性介孔材料在手性分离、不对称催化、手性传感等领域具有广泛的应用价值。手性有序无机介孔硅是一类介孔结构高度有序、不含有机成分的手性材料。该文采用D-苯丙氨酸为手性源合成手性有序无机介孔硅(COIMS),将其用聚硅氧烷(OV-1701)稀释后用作固定相制备毛细管气相色谱手性柱,并对该手性柱的分离性能进行了考察,8种手性化合物在该手性柱上得到了拆分。COIMS柱对直链烷烃、醇的分离也表现出良好的选择性。该柱还具有分析时间短、在较高温度下测定稳定等优点,其具有开发成高温手性固定相的潜力。     

5-[2'-氟-4'-溴-苯甲亚胺]-8-羟基喹啉铝的量子化学研究

应用密度泛函PBE0方法优化5-[2'-氟-4'-溴-苯甲亚胺]-8-羟基喹啉铝(AlA3)及5-[2'-氟-4'-溴-苯甲亚胺]-8-羟基喹啉(HA)的几何构型, 用TDDFT法计算其电子光谱, 对电荷转移及金属原子与配体的结合能进行了讨论. 计算结果表明: (1) AlA3配合物较稳定, 但结合能略低于8-羟基喹啉铝(AlQ3). 与AlQ3相比, AlA3的轨道作用较强, 静电作用较弱, 两者之和相近, 但AlA3排斥能较大. (2) 计算AlA3的两个电子吸收峰与实验结果相符. AlA3中的电荷由羟基喹啉基团通过Al原子在不同配体间转移呈现出最大吸收峰, 属于AlQ3类衍生物的特征吸收峰. 因为体系的共轭程度增大使LUMO轨道能降低, 电子跃迁需要的能量减少, 故吸收峰比AlQ3红移; (3) 290 nm吸收峰是电荷由CN基团向羟基喹啉基团转移产生的. 在喹啉环接上5-[2'-氟-4'-溴-苯甲亚胺]基团可望制备出波长更长的发光材料, 且增加了一个较强的吸收峰.     

Photoluminescence and Electroluminescence of Organic Light Emitting Diodes Based on Tris‐(8‐quinolinolato) Aluminum Nanoparticles

利用共沉淀方法制备出平均粒径为20nm的有机物8-羟基喹啉铝纳米粒子,8-羟基喹啉铝纳米粒子呈球形且粒度不随老化时间的增加而改变。本文研究了8-羟基喹啉铝纳米粒子的光致发光及基于8-羟基喹啉铝纳米粒子制作的电致发光器件的电致发光特性。8-羟基喹啉铝形成纳米粒子后,其光致发光及电致发光发射光谱的谱峰均出现蓝移。随着驱动电压的增加,器件中8-羟基喹啉铝纳米粒子的发射峰逐渐红移。在驱动电压为16伏时,8-羟基喹啉铝纳米粒子器件的最大亮度达600cd/m²,电流密度为150mA/cm^-2时,器件的发光效率为0.19cd/A。基于8-羟基喹啉铝纳米粒子器件的发射光谱证实了AlQ₃纳米粒子具有量子尺寸效应的存在,这为有机纳米电致发光器件的研究开辟了一条新的研究路线,同时也为那些传统的有机材料如有机分子晶体的基础研究探索出新的研究方向。     

含8-羟基喹啉铝配合物的高分子聚合物的合成与表征

通过甲基丙烯酸甲酯(MMA)和含有8-羟基喹啉的单体共聚合成模板聚合物,再与二配体的8-羟基喹啉铝配合物(AlQ2)配位,实现了8-羟基喹啉铝配合物的高分子化,获得了一种高分子量金属配合物发光聚合物,并利用元素分析,FTIR,UV,PL光谱,GPC等方法对其结构和性能作了表征．     

聚N-[5-(8-羟基喹啉)甲基]苯胺/介孔五氧化二钒杂化材料的制备与表征

采用原位插层聚合法制备出层状有序的聚N-[5-(8-羟基喹啉)甲基]苯胺/介孔五氧化二钒(PNQA/Meso-V2O5)杂化材料.结果显示,PNQA插入后,Meso-V2O5的层间距由2.4nm增加到2.81nm,得到的杂化材料仍保持良好的层状结构.杂化材料的室温电导率比Meso-V2O5高出3个数量级.荧光分析表明,在乙醇介质中杂化材料的发射谱带与PNQA相比蓝移22nm,杂化材料的荧光量子产率(26%)明显高于PNQA(10%).     

On-line preconcentration and separation of Co, Ni and Cd via capillary microextraction on ordered mesoporous alumina coating and determination by inductively plasma mass spectrometry (ICP-MS)

In this paper, an ordered mesoporous alumina coating was prepared and applied to capillary microextraction (CME) of trace Co, Ni and Cd for the first time. The coated capillary was used for on-line coupling CME with inductively plasma mass spectrometry (ICP-MS) for the determination of trace metals of Co, Ni and Cd. The porous structure of Al₂O₃ coating was examined by SEM and TEM. The effects of the extraction parameters including pH, sample flow rate and volume, elution solution and interfering ions on the recovery of analytes have been investigated and optimized. Under the optimized conditions, the limits of detection were 0.33, 1.5 and 1.4 ng L⁻¹ for Co, Ni and Cd, respectively, with a preconcentration factor of 10 times. The precisions for all investigated elements were 2.7, 4.1 and 2.5% (c = 0.05 ng L⁻¹, n = 7), for Co, Ni and Cd, respectively, and the sample frequency was 8 h⁻¹.The proposed method was successfully applied for the analysis of trace metals in water, rice and urine samples with the recovery of 94-105%. In order to validate the proposed method, two certified reference materials of GBW 0913 human urine and NIES No.10-b rice flour were analyzed, and the determination values are in good agreement with the certified values. The ordered mesoporous Al₂O₃ coated capillary can be used more than 20 times without decreasing the extraction efficiency.     

有序介孔硅片粒子表面的修饰及其表征

采用溶胶-凝胶的方法制备了粒径在50~300nm,具有正六边形的介孔二氧化硅片,用1,6-己二异氰酸酯(hexamethylene diisocyanate,HDI)对有序介孔硅片粒子表面进行有机化修饰,使其表面接枝能够参与反应的N=C=O活性基团。用FTIR、热重分析、TEM等分析方法对修饰后的有序介孔硅片粒子进行了表征,以确定HDI接在了有序介孔硅片粒子的表面。     

Ordered Mesoporous Silica Incorporating Platinum Nanoparticles as Electrode Material for Paracetamol Detection

High ordered mesoporous materials (SBA-15) modified with Al and/or B and Pt nanoparticles (Pt NPs) were used for preparing modified graphite paste electrodes (Pt/M−SBA-15-GPE, where M=Al−, B− or Al−B−) and applied for paracetamol (PA) detection. The electrodes were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Square wave voltammetry (SWV) technique was used to obtain the analytical parameters for PA detection. The acquired values of electrochemical and analytical parameters recommend the mesoporous compound containing Pt NPs to be used as composite electrode material for PA detection in real samples.     

Parts per quadrillion level ultra-trace determination of polar and nonpolar compounds via solvent-free capillary microextraction on surface-bonded sol-gel polytetrahydrofuran coating and gas chromatography-flame ionization detection

Sol-gel polytetrahydrofuran (poly-THF) coating was developed for high-sensitivity sample preconcentration by capillary microextraction (CME). Parts per quadrillion (ppq) level detection limits were achieved for both polar and nonpolar analytes through sample preconcentration on sol-gel poly-THF coated microextraction capillaries followed by gas chromatography (GC) analysis of the extracted compounds using a flame ionization detector (FID). The sol-gel coating was in situ created on the inner walls of a fused silica capillary using a sol solution containing poly-THF as an organic component, methyltrimethoxysilane (MTMOS) as a sol-gel precursor, trifluoroacetic acid (TFA, 5% water) as a sol-gel catalyst, and hexamethyldisilazane (HMDS) as a deactivating reagent. The sol solution was introduced into a hydrothermally-treated fused silica capillary and the sol-gel reactions were allowed to take place inside the capillary for 60 min. A wall-bonded coating was formed due to the condensation of silanol groups residing on the capillary inner surface with those on the sol-gel network fragments evolving in close vicinity of the capillary walls. Poly-THF is a medium polarity polymer, and was found to be effective in carrying out simultaneous extraction of both polar and nonpolar analytes. Efficient extraction of a wide range of trace analytes from aqueous samples was accomplished using sol-gel poly-THF coated fused silica capillaries for further analysis by GC. The test analytes included polycyclic aromatic hydrocarbons (PAHs), aldehydes, ketones, chlorophenols, and alcohols. To our knowledge, this is the first report on the use of a poly-THF based sol-gel material in analytical microextraction. Sol-gel poly-THF coated CME capillaries showed excellent solvent and thermal stability (>320 degrees C).     

Preparation of ordered mesoporous SiC from preceramic polymer templated by nanoporous silica

Highly ordered mesoporous SiC materials were prepared by infiltrating viscous liquid preceramic polymer, allylhydridopolycarbosilane, into two types of surface modified nanoporous silica templates: mesoporous silica SBA-15 and mesocellular siliceous foam. The silica templates were subsequently etched off after pyrolysis at 1000 degrees C under nitrogen atmosphere with the resultant formation of ordered mesoporous structures. The mesoporous SiC materials, synthesized from both types of templates possessed high Brunauer-Emmett-Teller (BET) surface areas in the range of 250-260 m(2)/g with pore sizes of 3.4-3.6 nm. The ordered structures of mesoporous SiC were exact inverse replicas of their respective silica templates, as characterized by small angle X-ray diffraction (XRD), transmission electron microscope (TEM) images, and the adsorption-desorption isotherm of nitrogen.     

A mesoporous silica nanoparticles immobilized open-tubular capillary column with a coating of cellulose tris(3,5-dimethylphenyl-carbamate) for enantioseparation in CEC

An approach of immobilizing mobile crystalline material (MCM)-41 mesoporous silica nanoparticles on the inner wall of an open-tubular (OT) capillary as the support for coating chiral selector of cellulose tris(3,5-dimethylphenyl-carbamate) (CDMPC) was carried out. By taking advantage of the improved phase ratio of OT capillary with the immobilization of MCM-41 mesoporous material, the cellulose derivative of CDMPC as the chiral selector was simply coated on the MCM-41 nanoparticle layer via the hydrogen-bonding interaction, and the enantioseparation was successively carried out. Eight pairs of acidic, neutral and basic enantiomers were resolved in capillary electrochromatography or capillary liquid chromatography mode. The concentration of CDMPC for coating was systematically investigated to obtain the optimized chromatographic properties on enantioseparation by controlling the supposed film thickness of CDMPC on MCM-41 nanoparticle layer. Comparing with a bare fused silica capillary column coated with CDMPC under the same coating procedure as MCM-41-modified capillary did, the MCM-41-modified capillary column offered much higher enantioselectivity. This result indicated the significance of using the mesoporous nanoparticles as the electrochromatographic support to enhance the phase ratio of OT capillary column in capillary electrochromatography and capillary liquid chromatography. For investigating the effect of experimental conditions on the enantioseparation with this prepared OT capillary column, the content of organic modifier acetonitrile in the mobile phase was thus extensively evaluated to achieve a better chiral separation.     

Nonaqueous capillary electrophoresis using a titania-coated capillary

In this work, an ordered mesoporous titania film was introduced to coat a capillary by means of the sol-gel technique. Its electroosmotic flow (EOF) property was investigated in a variety of nonaqueous media (methanol, formamide and N,N'-dimethylformamide and mixtures of methanol and acetonitrile). The titania-coated capillary exhibited a distinctive EOF behavior, the direction and magnitude of which were strongly dependent on various parameters such as the solvent composition, apparent pH (pH*) and the electrolytes. The nonaqueous capillary electrophoresis separation of several alkaloids was investigated in the positively charged titania-coated capillary. Comparison of separation between coated and uncoated capillaries under optimal nonaqueous conditions was also carried out.     

Effects of amino groups and microstructure of organic mesoporous silica supported metallocene catalysts on ethylene polymerization

<正>Mesoporous silica(MS),3-aminopropyltriethoxysilane(APTES) modified mesoporous silica(AMS),bis(3- trimethoxysilylpropyl)amine modified mesoporous silica(BAMS) and APTES modified solid spherical silica(AS) were prepared and used to immobilize metallocene catalysts for ethylene polymerization.Gel permeation chromatography results showed that polyethylenes(PEs) catalyzed by AMS(or BAMS) supported metallocene catalysts at the molar ratios of Al/Zr =100,300 and 500 were of bimodal molecular weight distribution(BMWD);while PEs catalyzed by the above catalysts at the molar ratios of Al/Zr≥800 were of monomodal molecular weight distribution(MMWD).However,MS(or AS) supported metallocene catalysts could only produce PEs with MMWD in spite of the molar ratio of Al/Zr.It was because that AMS(or BAMS) supported catalysts possessed two active sites for ethylene polymerization at low molar ratios of Al/Zr due to the combination effects of mesopore geometrical constraint and amino groups of the supports,which was confirmed by X-ray photoelectron spectroscopy.This brings forward a novel and easy method for the synthesis of polyolefin with BMWD.     

Electrochemical study of o-toluidine blue impregnated in mesoporous silica channels

This paper reports an electrochemical study of ordered mesoporous silica impregnated with a cationic dye (o-toluidine blue), prepared with a non-ionic surfactant as the structure-directing agent. O-toluidine blue was chosen because of its utility as an electron transfer mediator (redox catalyst). O-toluidine blue impregnated mesoporous silica was characterized by nitrogen sorption porosimetry, small angle X-ray scattering, infrared spectroscopy, scanning electron microscopy and cyclic voltammetry using chemically modified carbon paste electrodes. Results indicate that the dye is located within the ordered mesopores of micron-sized silica spheres.     

Silica‐modified Electrodes for Electrochemical Detection of Malachite Green

New silica‐modified glassy carbon electrodes prepared with three different sorts of ordered mesoporous silica (OMS) were characterized and tested for the electrochemical detection of Malachite Green (MG). The electrodes were prepared by drop casting using silica suspensions and, for stability sake, a Nafion coating was deposited on the electrode top by the same technique. Square wave anodic stripping voltammetry was used to investigate the effect of various experimental parameters (deposition time, solution pH, silica type and concentration) on the performance of the modified electrodes. The best electrode (GC/MCM‐41‐NH₂/Nafion) with detection limit 0.36 μM, sensitivity 0.164±0.003 A/M; linear domain 1–6 μM was applied to detect MG in a commercial product commonly used as biocide in aquaria for ornamental fish.