Preparation of in-situ Pt nanoparticles into frameworks of mesoporous silica for improving thermal stability

The Pt/sulfur-containing mesoporous silica (SMS) was obtained through in-situ co-condensation of TESPTS and TEOS in the presence of a triblock copolymer template. Strong interaction between the Pt NPs and S moieties of TESPTS in the SMS frameworks played an important role in the stabilization of Pt NPs against the sintering or coalescence problems. The Pt/SMS significantly improved the thermal stability at high temperature.     

巯基功能化短孔道有序介孔材料HS-Zr-Ce-SBA-15的合成及吸附性能

以P123为模板剂,正硅酸乙酯（TEOS）为硅源,氧氯化锆和硝酸亚铈为无机前驱盐,3-巯基丙基-三甲氧基硅烷（MPTMS）为硅烷化试剂,通过一步共缩聚法合成了巯基功能化短孔道有序介孔材料HS-Zr-Ce-SBA-15（HS-ZCS）。采用红外光谱（FT-IR）、小角X射线衍射（LXRD）、透射电镜（TEM）、扫描电镜（SEM）、N2吸附/脱附、热重分析（TG）等手段对HS-ZCS进行了表征。结果表明MPTMS成功地引入到有序介孔材料上,HS-ZCS仍保持了类似于传统SBA-15高度有序的二维六方相介孔结构。对罗丹明6G的吸附实验表明,这种功能化短孔道介孔材料表现出比传统的长孔道SBA-15有更好的传输能力。     

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.     

有机-无机杂化复合材料的合成、表征和热学性质

丙烯酸乙酯(EA)、甲基丙烯酸甲酯(MMA)、苯乙烯(St)、及丙烯酸丁酯(BA)分别和含烷氧基硅烷单体甲基丙烯酰氧基三甲氧丙基硅烷以一定比例通过自由基共聚反应制得共聚物前驱体,将TEOS在HCl催化剂作用下水解、缩合形成SiO2,然后由共聚物和SiO2通过溶胶-凝胶法合成杂化复合材料,制得的复合材料膜有较好的光学透明性,其透光率在79%以上.利用傅立红外光谱分析了杂化材料的化学结构.溶胶抽取结果表明,在杂化材料中凝胶的含量较高,对它们的形貌特性和研究结果表明:在聚合物基体中SiO2具有较好的分散性,有机-无机相相互贯穿.     

Fabrication of hollow silica spheres and their application in polyacrylate film forming agent

Polystyrene (PS)/silica core/shell spheres were fabricated using mono-dispersed PS as templates by hydrolysis and condensation of two different silica precursors. The PS cores of PS/silica core/shell spheres were dissolved subsequently in the tetrahydrofuran medium to form mono-dispersed hollow silica spheres. The structures and morphologies of hollow silica spheres were characterized by scanning electron microscopy and transmission electron microscopy. Then, polyacrylate/hollow silica composite film forming agents were prepared via physical blending of polyacrylate and two different hollow silica spheres, and the water vapor permeability of their films were compared. The results showed that the structure of hollow silica spheres were very typical and obvious. The silica shell was continuous and uniform using tetraethylorthosilicate as precursor, which was accumulated by many silica seeds with size of 10–20 nm, and the thickness of silica shell was about 16.7 nm. However, the hollow silica spheres using tetraethylorthosilicate and vinyl triethoxysilane as precursors had mesoporous structure in the shell. The introduction of hollow silica spheres could significantly improve the water vapor permeability of polyacrylate film. At last, a possible mechanism for the formation of hollow silica spheres was proposed and the process of water vapor through polyacrylate/hollow silica composite films was modeled.     

聚乙二醇对纳米多孔二氧化硅薄膜性能的影响

以聚乙二醇(PEG)为添加剂,正硅酸乙酯(TEOS)为先驱体,采用溶胶-凝胶法、结合 旋转涂胶和超临界干燥等工艺在硅片上制备了纳米多孔SiO₂薄膜.利用FTIR、TG-DTA、 AFM和椭偏仪研究了该SiO₂薄膜的性能.与未加.PEG的SiO₂薄膜相比,加入PEG得到 的SiO₂薄膜表面粗糙度增大,但孔隙率较高,介电常数可降至2.0以下.PEG参与并修饰了 TEOS的溶胶-凝胶过程.加入PEG制备的SiO₂薄膜因含有Si-OH基团而呈亲水性,该薄 膜经三甲基氯硅烷(TMCS)修饰后为疏水性.     

Electrospinning of porphyrin/polyvinyl alcohol (PVA) nanofibers and their acid vapor sensing capability

Fluorescing 5,10,15,20-terakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP)-embedded and -coated polyvinyl alcohol (PVA) nanofibers were fabricated by using the electrospinning technique. To improve nonpolar solvent solubility of TMPyP/PVA nanofibers, tetraethyl orthosilicate (TEOS) was used as a cross-linking agent. UV-vis spectroscopy showed a strong Q band and two relatively weak Soret bands from the TMPyP/PVA nanofibers, and revealed that the TMPyP molecules were homogeneously loaded to the fibers. Scanning electron microscopy revealed that the electrospun nanofibers had ultrafine structures with an average diameter of ca. 250 nm. X-ray photoelectron spectroscopy confirmed the compositional structure of TMPyP/PVA/TEOS nanofibers and revealed the relative coverage of TMPyP molecules on the surface of TMPyP-embedded and TMPyP-coated PVA/TEOS fibers. For the comparison of the acid vapor sensitivity, TMPyP-embedded PVA/TEOS films, and TMPyP-embedded PVA/TEOS fibers, TMPyP-coated PVA/TEOS fibers were exposed to 1N nitric-acid vapor for 20-60 seconds. Fluorescence microscopy revealed that TMPyP-coated PVA/TEOS nanofibers exhibited better acid-sensing capability than TMPyP-embedded PVA/TEOS nanofibers and films.     

Poly(L-lysine)-poly(ethylene glycol) layers with different structure and their influence on silica suspension stability

The effects of the structure of di- and triblock copolymers of poly(L-lysine) – LYS with poly(ethylene glycol) – PEG as well as the length of nonionic fragment in the LYS-PEG macromolecule on the copolymer chains conformation in the adsorption layer formed on the colloidal silica (SiO2) surface were examined. Spectrophotometry and turbidimetry were applied for the determination of copolymer adsorbed amounts and stability coefficients of silica aqueous suspensions. The electrokinetic parameters such as solid surface charge density and zeta potential were also estimated. The adsorption of LYS-PEG was proved to be the highest at pH 10 whereas the lowest adsorption on the solid surface was found for the triblock copolymer with long fragments of LYS at the same pH value.     

ISI/IMs共混型镶嵌荷电膜的研制

以嵌段共聚物ＩＳＩ和ＩＭｓ的共混物为原料，ＰＰ微孔膜为基膜制成了复合膜，再经过交联、季胺化和磺化而制成了一种新的共混型镶嵌荷电膜。进一步的研究显示，该膜具有典型的镶嵌荷电膜结构及性能特点，与ＭｓＩＳＩＭｓ五嵌段荷电膜具有相似的膜形态与膜结构；电性能也十分相近，膜面电阻分别为３５０、９７０Ω·ｃｍ＾２，电压渗系数分别为８×１０＾－９、６．１×１０＾－９Ｖ／Ｐａ。表明可以用ＩＳＩ／ＩＭｓ共混物代替五嵌     

AFM Tip Hammering Nanolithography

Nanolithography at low cost and high speed is made possible by using a vibrating AFM tip in tapping‐mode as a nanohammer to forge polystyrene‐block‐poly(ethylene/butylenes)‐block‐polystyrene triblock copolymer monolayer thin films after annealing to transform their microstructures from as‐cast poorly ordered cylinders into well‐ordered hexagonal spheres. Annealing is accomplished in cyclohexane vapor, a selective solvent for the majority poly(ethylene/butylenes) block. Experimental results demonstrate that such structure‐tailored thin films enable macroscopic AFM tip writing to be performed in their surface; imprinted and embossed patterns can be generated with a sub‐20‐nm line‐width resolution. In addition, it is found that the lithographic patterns generated can be erased within 5 min by thermal annealing at 70 °C, and if necessary the erasion process can be expedited by increasing the annealing temperature.     

蒸发诱导自组装仿生合成高有序度三维六方介孔氧化硅薄膜

借鉴自然界生物矿化的形成机理,利用蒸发诱导自组装(EISA)的方法,以十六烷基三甲基溴化铵(CTAB)为结构导向剂,正硅酸乙酯(TEOS)为硅源,通过浸渍提拉在普通玻璃片上制备出高有序度、三维六方结构的介孔氧化硅薄膜,通过XRD、TEM、低温N2吸附/脱附等方法对薄膜进行了表征,并初步讨论了形成三维六方结构的机理.     

One-step synthesis of hydrophobic mesoporous silica ellipsoidal particles with a bimodal mesopore system

Highly CH₃-functionalized mesoporous silica ellipsoidal particles with bimodal mesopore structure were prepared via a one-step route using polymethylhydrosiloxane (PMHS) and tetraethoxysilane (TEOS) with triblock copolymer P123 as template under acidic conditions. N₂ adsorption–desorption, XRD, HRTEM, SEM and ²⁹Si MAS NMR were used to characterize the obtained material. The introduction of PMHS into the synthetic system led to the formation of a bimodal mesopore system consisting of framework mesopores of ∼7.2 nm and textural mesopores of ∼29.4 nm. The two scale pores were directly observed in HRTEM images and indirectly proved by the two-step increase in N₂ adsorption–desorption isotherm. Also, PMHS played an important role in morphology controlling and organic functionalization, ensuring monodisperse ellipsoidal particle morphology and high CH₃ functionalization degree of the mesoporous silica product. Subjected to removing highly diluted nonylphenol from aqueous solution, the hydrophobic bimodal mesoporous silica ellipsoidal particles showed high adsorption performance.     

非水体系快速挥发法直接合成有序介孔炭

采用非水溶剂快速挥发法,以表面活性剂和酚醛树脂为结构导向剂和碳前驱体制备介孔炭.通过透射电镜、氮吸附-脱附和扫描电镜对产品的结构进行了表征.结果表明:所制介孔炭具有高度有序的二维六方结构.表面活性剂与酚醛树脂的配比对介孔炭的有序性有较大的影响,当其质量比高于1:0.25时,可保持良好的有序度.随着比值的减小,有序度逐渐降低.与蔗糖液相浸渍法相比,非水体系快速挥发法所制介孔炭具有较少的外微及大孔.     

SBP嵌段共聚物的合成和鉴定EI

用正丁基锂为引发剂,四氢呋喃为添加剂,按阴离子顺序加料方法合成了聚苯乙烯-丁二烯-4-乙烯吡啶(SBP)嵌段共聚物,经FTIR、UV、DSC、DDV等测试方法表征,证实了所合成的聚合物为聚苯乙烯-丁二烯-4-乙烯基吡啶嵌段共聚物。研究表明4-乙烯吡啶在聚合体系中聚合反应极为迅速且由于吡啶环上N原子对碳阴离子较为敏感,故嵌段共聚物中含有部分分子量较高的支化高分子。透射电镜表明样品具有精细的微相结构。聚合物的微相结构随聚合物中聚丁二烯含量提高,可以从蜂窝状结构转变成层状结构。     

缓冲溶液中制备掺杂高度隔离铁物种的介孔氧化硅(英文)

使用P123作为模板剂,采用不同的硅源(正硅酸甲酯,正硅酸乙酯,硅酸钠)在弱酸性的条件下(pH=4.4,乙酸-乙酸钠缓冲溶液)合成掺杂铁的介孔氧化硅材料.正硅酸甲酯和硅酸钠形成有序的二维六方相的介孔结构,而正硅酸乙酯形成了囊泡结构.紫外可见漫反射光谱和紫外共振拉曼光谱表明,在环境友好的条件下,采用硝酸铁和硅酸钠可以合成出高度隔离的铁物种.缓冲溶液提供了一条便捷的途径,通过简单改变硅源来控制介孔结构.掺杂铁的介孔氧化硅材料在苯酚的羟化反应中表现出优异的催化性能,主要由于铁物种高度分散在氧化硅载体上,介孔结构使铁活性位更易于接近反应物分子.     

疏水改性对SiO2气凝胶薄膜性能与结构的影响

以正硅酸乙酯(TEOS)为前驱体,采用溶胶-凝胶法制备SiO2气凝胶薄膜,并以不同体积分数的六甲基二硅胺烷(HMDZ)对SiO2气凝胶薄膜进行了疏水改性研究,采用椭偏仪、FITR、接触角测试仪、SEM和光谱仪等对薄膜的疏水性、微观结构及透光性进行了表征,研究了HMDZ疏水改性对SiO2气凝胶薄膜性能与结构的影响。结果表明,疏水改性后,SiO2胶粒表面的大部分亲水性-OH被疏水基团-CH3所取代,其与水的接触角达159°,疏水性好;SiO2气凝胶薄膜在可见光范围内透光率接近90%,透光性高;其孔隙率为78.8%,密度为0.464g/cm3,骨架颗粒尺寸小于40nm,具有纳米多孔网络结构特性。     

Aligned bioactive mesoporous silica coatings for implants

Ongoing research is reported aimed at preparing mesoporous silica coatings on various substrates for medical applications by a biomimetic approach (self-assembling of organic/inorganic sol-gel systems into ordered structures). Tetraethylorthosilicate (TEOS) was selected as the silica precursor, and amphiphilic triblock copolymers poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), and the cationic surfactant cetyltrimethyl ammonium chloride (CTAC), as structure-directing agents. The mesochannels diameter could be adjusted by changing the directing agent, and a preferred alignment of the mesostructure was observed independently of the used substrate (glass, silicon, Ti or Ti6Al4V). Three different treatments (thermocalcination, photocalcination, and solvent extraction) have been also studied to remove the organic templates, of which photocalcination showed to be the most versatile. When soaked in a simulated body fluid, mesoporous silica coatings induced apatite formation after seven days.     

Fabrication and characterization of novel meso-porous carbon/n-octadecane as form-stable phase change materials for enhancement of phase-change behavior

In this study, series of novel composite phase change materials (PCMs) were prepared through vacuum impregnation by using meso-porous carbon as a supporting matrix and n-octadcane as PCMs. The meso-porous carbon material was prepared through one-pot co-assembly method, using resorcinol and formaldehyde as carbon precursor, tetraethoxysilane as silica sources and triblock copolymer F127 as a template. And the phase behaviors of n-octadcane confined in the nano-porous structure of the meso-porous carbon were further investigated. Fourier transform-infrared spectroscopy spectra show that n-octadecane was effectively encapsulated in the porous structure of mesoporous carbon and the composite PCMs were successfully prepared. Differential scanning calorimetry results confirm that the composite PCMs possess a good phase change behavior, fast thermal-response rate and excellent thermal cycling stability. In addition, the composite PCMs possess expected heat storage and heat release properties. All these results demonstrate that the composite PCMs possess good comprehensive property so that they can be used widely in energy storage systems.     

Ordered mesoporous silicon through magnesium reduction of polymer templated silica thin films

This paper describes the process of making ordered mesoporous silicon (Si) thin films. The process begins with mesoporous silica (SiO 2) thin films that are produced via evaporation induced self-assembly (EISA) using sol-gel silica precursors with a diblock copolymer template. This results in a film with a cubic lattice of 15 nm diameter pores and 10 nm thick walls. The silicon is produced through reduction of the silica thin films in a magnesium (Mg) vapor at 675 degrees C. Magnesium reduction preserves the ordered pore-solid architecture but replaces the dense silica walls with 10-17 nm silicon crystallites. The resulting porous silicon films are characterized by a combination of low and high angle X-ray diffraction, combined with direct SEM imaging. The result is a straightforward route to the production of ordered nanoporous silicon.     

Ultra low-dielectric-constant methylated mesoporous silica films with high hydrophobicity and stability

Vapor phase treatment with tetraethyl orthosilicate (TEOS) is used to improve the performance of methylated mesoporous silica films spin-coated on silicon wafers. Subsequent calcination leads to formation of ultra low dielectric-constant (k) films with high hydrophobicity and structural stability. The k value of the films is about 1.75, and remains as low as 1.82 in an 80%-relative-humidity environment over seven days. Mechanical strength (elastic modulus and hardness) is high enough to withstand the stresses that occur during the chemical mechanical polishing and wire bonding process (E = 10.9 GPa). Effects of the methyl group and TEOS vapor treatment on the structural stability and hydrophobicity are systematically studied.