同质异构_SSiO_2/_MSiO_2核/壳复合磨粒的合成

以正硅酸乙酯为硅源、以氨水为催化剂、十六烷基三甲基溴化铵为结构导向模板剂,在单分散实心氧化硅(Solid-SiO2,SSiO2)内核表面包覆介孔氧化硅(Mesoporous-SiO2,MSiO2)外壳,合成了同质异构氧化硅(SSiO2/MSiO2)核/壳复合磨粒。用小角XRD、FESEM、HRTEM、FTIR、TGA和氮气吸附-脱附等手段对样品的结构进行了表征。结果表明,具有放射状介孔孔道的MSiO2均匀连续包覆在SSiO2内核(210-230nm)外表面,形成了厚度为70-80nm的外壳。壳层中的介孔孔道(孔径约2-3nm)基本垂直于内核表面,且复合磨粒样品具有较大的比表面积(558.2m2/g)。用AFM形貌分析和轮廓分析评价了所制备的复合磨粒对SiO2薄膜的抛光特性。与常规实心SiO2磨粒相比,SSiO2/MSiO2复合磨粒明显改善了抛光表面质量并提高了材料去除率。这可能归因于MSiO2壳层通过机械和/或化学方面的作用对磨粒与衬底之间真实界面接触环境的优化。     

工业TiOSO4液合成有序介孔TiO2分子筛的研究

以工业TiOSO4液为原料,在复合模板剂十二胺和十六烷基三甲基溴化铵(CTAB)的超分子自组装诱导作用下,合成出有序介孔TiO2.通过控制溶液pH值有效调控TiOSO4液的水解缩聚速率,使得水合二氧化钛均匀沉积于复合模板剂形成的胶束上,在脱除模板剂后得到介孔材料.产物采用XRD、粒度分布测试、SEM、TEM、电子衍射及等温N2吸附进行分析表征.研究表明:介孔TiO2具有精细纳米结构,孔道分布窄,平均孔径2.2nm,BET比表面积为135.9m2/g,孔隙率31%,孔容0.17cm3/g;介孔TiO2的孔壁部分晶化为锐钛型,晶粒尺寸为37nm,粒子介于30～80nm间,聚集的粉末颗粒为类球形.     

可溶性酚醛树脂为碳源合成有序介孔炭及其电催化性能

利用介孔硅SBA-15与苯酚、甲醛混合,原位合成可溶性酚醛树脂,高温炭化得有序介孔炭(C1);同时将预聚的酚醛树脂与SBA-15 共混后再聚合,高温炭化得有序介孔炭(C2).微波多元醇还原法合成Pt/C1、Pt/C2、Pt/CMK-5(糠醇为碳源)电催化剂.使用X射线衍射仪(XRD),N2物理吸附,透射电镜(TEM)和循环伏安技术(CV)对介孔炭的结构和催化剂的性能进行了表征.结果表明:CI主要由规则的六方介孔孔道构成,比表面积为947m2/g,孔径分布集巾在4.5nm,Pt微粒在C1上具有良好的分散性,平均粒径约为3nm.C2的孔道较为模糊,负载的Pt微粒有一定程度的团聚.CV曲线显示,Pt/C1催化剂的电化学活性面积(EAS)为54.2m2/g,其催化甲醇氧化的性能优于Pt/C2及Pt/CMK-5而略筹于商用催化剂Pt/C(E-TEK).     

氰基功能化介孔二氧化硅的制备与表征

以2-氰乙基三乙氧基硅烷(CTES)和正硅酸乙酯(TEOS)为硅源,聚氧乙烯聚氧丙烯聚氧乙烯三嵌段共聚物(P123)为模板剂,采用共缩聚法在酸性条件下合成了氰基功能化的介孔二氧化硅.通过XRD、SEM、氮气吸附脱附、FT-IR和元素分析等技术对样品的结构、形貌、孔性质和官能团等进行了表征.研究结果表明,硅源的混合方式对氰基的引入量和分布有一定影响,其中以直接混合方式所得样品中基团含量最高,其分布也最均匀.另外,随着氰基引入量的增加,样品的形貌与孔结构略有变化.当CTES加入量超过20mol%时,材料的介孔由圆柱形的直孔道向瓶颈型的孔道结构发生转变.同时随着材料中氰基含量增大,样品的孔容由0.70 cm3/g降到0.22 cm3/g、表面积从666 m2/g降到312 m2/g,孔径由4.2 nm减小到2.7 nm,表明氰基分子占据了部分孔道空间.     

双模板结构导向剂制备有序介孔炭

以间苯二酚/甲醛制备的酚醛树脂为碳前躯体,三嵌段共聚物F127和P123作为主辅结构导向剂,采用有机-有机自组装的方法制备有序介孔炭(Ordered mesoporous carbons,简称OMCs)。采用X射线衍射仪、透射电镜和N2吸/脱附手段对所制OMCs进行表征,研究了反应时间以及主辅模板剂的比例对介孔孔道结构的影响。结果表明,随着反应时间从24h延长至72 h,介孔炭有序性先增后减;当主辅模板剂F127/P123摩尔比为0.002 7∶0.002 7时,所得介孔炭有序性较好,为P6mm型孔道结构,介孔孔容和比表面积分别为0.59 cm3/g和640.34 m2/g,平均孔径为3.68 nm.     

以冰晶体为模板制备蒙脱石质介孔材料及表征

探索了以冰晶体为模板制备钠基蒙脱石质(Na-MMT)介孔材料的可行性. 当蒙脱石(MMT)微凝胶分散液的浓度控制在1.8%~2.1%范围, MMT微粒在0.15~0.60μm之间时, 冻干后的MMT微粒呈层状分布, 且具有宏观层状组装纹理. MMT多孔结构体系中存在着介孔结构, 介孔孔径主要分布在35~45nm, 介孔孔隙呈现出楔形特征. 其晶胞层间距d(001)由1.238nm 增至1.901nm, 比表面积由原始的16.5m²/g增至213.6m²/g.     

纳米浇注法制备有序介孔WC/C复合材料及电催化性能

以介孔SiO2为硬模板,通过纳米浇注法在模板孔道中引入不同质量配比的碳源和钨源前驱物,经过高温碳化还原反应,刻蚀除去模板后得到了介观结构有序的SBA-15和KIT-6介孔碳化钨/炭(WC/C)复合材料。采用XRD、TEM、EDX、TGA、CV和N2吸附-脱附等测试手段,对所得复合材料进行了物化性质分析和结构表征。结果表明,该介孔WC/C复合材料具有有序的介观结构(p6mm,Ia3d)、高的比表面积(约500m2/g)和较大的孔径(约4nm)。CV测试表明,三维贯通的有序TC/C-KIT-6为载体负载Pt催化剂,对甲醇的催化氧化具有更优异的作用。     

离子液中介孔TiO2的制备及其形成机理研究

首次以不同咪唑基离子液为结构导向剂，通过水热合成制备出介孔TiO2分子筛。考察了合成条件对产物结构的影响，结果表明，离子液用量、离子液类型、晶化温度、晶化时间等因素对TiO2介孔分子筛的形成和孔道结构均有影响，其中晶化温度及离子液类型的影响最为明显，在较低晶化温度时（100℃）产物孔径分布范围宽，但仍为介孔结构，当温度升高到180℃时，孔径变大并开始失去介孔特征，机理为晶化温度会影响离子液与无机物的相互作用速度，高温时TiO2结晶度也会迅速提高导致失去介孔结构，最佳晶化温度为120℃；咪唑基离子液其碳链长度不同，使用短链离子液时产物无介孔结构，当使用长链离子液时产物孔道结构良好，作为结构导向剂其碳链长度会决定产物孔道生长趋势和长度，最佳离子液类型为[C16MIM]Br．X射线衍射谱（XRD）表明产物为锐钛矿型介孔TiO2；透射电镜（TEM）观察表明产物具有规整的孔道结构（3～4nm），与低温氮吸附法分析结果一致；激光粒度分析表明产物粒度较小（20～40nm）并且分布范围窄。     

核/壳结构PS/_MSiO_2复合颗粒的制备和压缩弹性模量

以用聚乙烯吡咯烷酮(PVP)表面修饰的聚苯乙烯(PS,约260 nm)微球为内核并利用PVP与十六烷基三甲基溴化铵之间的液相协同自组装过程,制备出以介孔氧化硅(Mesoporous silica,MSiO_2)为包覆层的核/壳结构PS/MSiO_2复合颗粒。结果表明,在样品壳层中有大量的放射状介孔孔道,壳层的厚度约为60 nm;样品的比表面积为848 g/m2,平均孔径为2.54 nm。根据单个复合颗粒的力曲线,使用Hertz弹性接触模型拟合出样品的压缩弹性模量为(4.47±0.83)(泊松比取值0.33)和(4.89±0.89)GPa(泊松比取值0.2)。对比结果表明,壳层中丰富介孔孔道有利于提高有机/无机复合颗粒的弹性响应。     

两步晶化法制备MCM-48/ZSM-5复合分子筛

利用两步晶化法制备了高水热稳定性的MCM48/ZSM-5介微孔复合分子筛.通过SEM、TEM、XRD、IR和N₂吸附脱附进行表征,结果显示,该材料的结构不同于简单的机械混合,而是具有微孔孔壁和三维立方介孔孔道的复合材料,其孔道尺寸为2.6nm左右.该复合分子筛在沸水中处理6h后,介孔结构仍保留完好.通过考察晶化时间对复合分子筛的影响,证明了介孔和微孔的组装是一个竞争的过程,复合分子筛中介孔与微孔结构的比例随晶化时间的变化而变化,且具有介孔孔道和微孔孔壁的复合分子筛150℃的最优晶化时间为8h.     

Influence of reaction parameters on size and shape of silica nanoparticles

It was investigated that the effect of various synthesis parameters such as, types of silicon alkoxides and alcohols, ammonia (catalyst) concentration, and reaction temperature on the particle size and shape of silica nanosphere by Sol-Gel method. When different silicon alkoxides were used, the silica particles except tetramethylorthosilicate (TMOS), all were spherical, and after reaching a maximum, the sizes were decreased with carbon chain length due to its steric effect. As the alcohol chain length increased from methanol (MeOH) to n-butanol (BuOH), the average particle size was increased from 30 nm to 800 nm. In general, all are having narrow particle size except BuOH sample were distributed bimodally (150 and 800 nm). When ammonia concentration increases, the particles also increased, however on increasing the reaction temperature, the particle sizes were reduced.     

Solution assisted laser ablation synthesis of discrete aluminum nanoparticles

Discrete aluminum nanoparticles with an average particle size of 21 nm have been prepared by laser ablation of a metallic aluminum target submerged in dry tetrahydrofuran in the presence of 0.001 M oleic acid as a stabilizing ligand. The particles display high solubility and minimal aggregation while the absence of oleic acid leads to highly aggregated particles and a broader particle size distribution. O/Al ratios obtained from EDS analysis suggest that the particles produced are primarily metallic aluminum with minimal oxide content.     

Particle formation in ambient MALDI plumes

The ablated particle count and size distribution of four solid matrix materials commonly used for matrix-assisted laser desorption ionization (MALDI) were measured with a scanning mobility particle sizer (SMPS) combined with a light scattering aerodynamic particle sizer (APS). The two particle sizing instruments allowed size measurements in the range from 10 nm to 20 μm. The four solid matrixes investigated were 2,5-dihydroxybenzoic acid (DHB), 4-nitroaniline (NA), α-cyano-4-hydroxycinnamic acid (CHCA), and sinapic acid (SA). A thin film of the matrix was deposited on a stainless steel target using the dried droplet method and was irradiated with a 337 nm nitrogen laser at atmospheric pressure. The target was rotated during the measurement. A large number of nanoparticles were produced, and average particle diameters ranged from 40 to 170 nm depending on the matrix and the laser fluence. These particles are attributed to agglomeration of smaller particles and clusters and/or hydrodynamic sputtering of melted matrix. A coarse particle component of the distribution was observed with diameters between 500 nm and 2 μm. The coarse particles were significantly lower in number but had a total mass that was comparable to that of the nanoparticles. The coarse particles are attributed to matrix melting and spallation. Two of the compounds, CHCA and SA, had a third particle size distribution component in the range of 10 to 30 nm, which is attributed to the direct ejection of clusters.     

单分散聚苯乙烯乳胶粒的制备及其二维胶体晶体的自组装

以自合成的平均粒径为95.7 nm、粒径分布指数为0.047的聚苯乙烯乳胶粒为种子,采用种子乳液聚合方法制备出单分散的聚苯乙烯乳胶粒,探讨了控制胶粒粒径大小及分布的方法及制备条件.结果表明,在种子乳液聚合中,通过控制单体加入量和乳化剂的补加速度,可以得到单分散聚苯乙烯乳胶粒;当没有新的胶束生成且乳胶粒子没有发生聚结时,乳胶粒尺寸和分布有自身变窄的倾向,得到了平均粒径为261.6 nm、粒径分布指数为0.021的单分散乳胶粒.采用毛细管作用力驱动的微粒自组装技术进行单分散胶粒的组装,获得了二维有序聚苯乙烯胶体晶体,并用场发射扫描电子显微镜表征了其二维有序结构.     

Effects of aerosol heating rate on the properties of aggregates of lead zirconate titanate nanoparticles produced by spray pyrolysis

The dependence of the shape and size distribution of aggregates of lead zirconate titanate nanoparticles prepared by spray pyrolysis of a sol–gel precursor solution is reported. Decreasing the average heating rate from 300 to 160 °C s⁻¹ in the sub-200 °C section of the reactor decreased the proportion of non-spherical particle aggregates and decreased the maximum size from ~10 to ~5 μm. Microtome sectioning revealed an internal structure composed of <100 nm primary particles. Both solid and hollow particle aggregates were present.     

In vitro and transdermal penetration of PHBV micro/nanoparticles

The purpose of this study was to develop micro and nano sized drug carriers from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and study the cell and skin penetration of these particles. PHBV micro/nanospheres were prepared by o/w emulsion method and were stained with a fluorescent dye, Nile Red. The particles were fractionated by centrifugation to produce different sized populations. Topography was studied by SEM and average particle size and its distribution were determined with particle sizer. Cell viability assay (MTT) was carried out using L929 fibroblastic cell line, and particle penetration into the cells were studied. Transdermal permeation of PHBV micro/nanospheres and tissue reaction were studied using a BALB/c mouse model. Skin response was evaluated histologically and amount of PHBV in skin was determined by gas chromatography-mass spectrometry. The average diameters of the PHBV micro/nanosphere batches were found to be 1.9 μm, 426 and 166 nm. Polydispersity indices showed that the size distribution of micro sized particles was broader than the smaller ones. In vitro studies showed that the cells had a normal growth trend. MTT showed no signs of particle toxicity. The 426 and 166 nm sized PHBV spheres were seen to penetrate the cell membrane. The histological sections revealed no adverse effects. In view of this data nano and micro sized PHBV particles appeared to have potential to serve as topical and transdermal drug delivery carriers for use on aged or damaged skin or in cases of skin diseases such as psoriasis, and may even be used in gene transfer to cells.     

SYNTHESIS AND CHARACTERIZATION OF CONTROLLED SIZES: POLYSTYRENE LATEXES

Several parameters and their limitations to prepare monodisperse polystyrene particles were discussed. Polystyrene latexes B, C and D of diameter 129.8, 142.8 and 264.5 nm, respectively, were synthesized by emulsion polymerization method. The latex D is almost monodisperse with very low polydispersity of 0.005 while B and C are having polydispersity of 0.1837 and 0.1601. The particle size and particle size distribution of the latexes were determined by a TEM and Brookhaven particle size analyzer. It was observed that the particle size of the latexes decreased with increasing initiator (ammonium persulfate) or surfactant (SDS) concentrations. The surface area of the latexes were calculated by using BET equation on the basis of the amount of nitrogen gas adsorbed at the surface of the particles to form a monolayer. It was observed that the surface area of latex D is less than B and C because of the bigger size of the particles. The average molecular weights, zeta potentials and densities of the latexes were also presented.     

碳包覆NiO纳米颗粒的制备与性能

采用直流电弧放电等离子体技术成功制备了碳包覆NiO(NiO@C)纳米颗粒,并对样品的形貌、晶体结构、粒度、比表面积和孔结构采用高分辨透射电子显微镜、X射线衍射、X射线能量色散分析谱仪、拉曼散射光谱和N_2吸-脱附等测试手段进行了分析。实验结果表明:直流电弧等离子体技术制备的NiO@C纳米颗粒具有典型的核壳结构,内核为面心立方结构的NiO纳米颗粒,外壳为碳层。颗粒形貌主要为立方体结构,粒度均匀,分散性良好,粒径分布在30~70nm范围,平均粒径为50nm,外壳碳层的厚度为5nm。NiO@C纳米颗粒BET比表面积为28m~2/g,等效直径为46nm,与TEM和XRD测得的结果基本一致。Raman光谱说明样品中碳包覆层的石墨化程度较低,发生了红移现象。     

Preparation of surfactant templated nanoporous silica spherical particles by the Stöber method. Effect of solvent composition on the particle size

Monodispersed nanoporous silica spherical particles with the particle size ranges from 0.01 μm to 1.5 μm were successfully prepared by the Stöber method combined with supramolecular templating approach. The particles formed from homogeneous solutions containing tetraethoxysilane, cetyltrimethylammonium chloride, methanol, and aqueous ammonia solution at room temperature. In the present study, methanol/tetraethoxysilane ratio was the factor to control the particle size. With increasing the methanol/tetraethoxysilane ratios from 1,125 to 6,000, particle size decreased from 1.5 μm to 0.01 μm. The calcination of the particles resulted in the spherical porous silicas with the average pore sizes of around 2.0 nm irrespective of the particle size. The particle morphology retained after the calcination.     

含Cu取向硅钢中第二相粒子析出演变行为研究

使用场发射扫描电子显微镜(SEM)观察CGO硅钢制备过程中第二相粒子的析出行为及分布状态,统计粒子的平均尺寸、面密度及Zener因子。结果表明:试样中主要存在两种析出物,一种是(Cu,Mn)S复合析出物,尺寸为1μm左右,称为A类析出物,另一种是Cu_2S析出物,尺寸为10~30nm,称为B类析出物,Cu_2S起主要抑制作用。第二相粒子在热轧阶段大量弥散析出,平均粒子尺寸最小,面密度最高,高温退火前的加工阶段,粒子的平均尺寸不断增加,面密度逐渐降低;高温退火过程中,随着析出物体积分数的降低,其抑制能力呈下降趋势,960℃时析出物发生明显的聚集现象,当Zener因子A低于临界值0.19nm~(-1)时,二次再结晶发生,残留的粒子不会产生有效的抑制作用。