由纳米晶前驱体组装有序介孔silicalite-1分子筛

采用两步法将不同尺寸的silicalite-1分子筛纳米晶种通过自组装合成了一系列有序介孔silicalite-1分子筛。首先将强碱性的silicalite-1前驱体分别加热不同时间得到纳米晶种,然后在类似合成SBA-15的强酸性条件下组装成有序的介孔材料。合成条件的剧烈变化阻止了分子筛晶种的继续长大,并在三嵌段共聚物模板的诱导下组装成有序介孔材料。这种“自下而上”的方法制备有序介孔分子筛同时包含微孔和介孔。氮气吸脱附结果表明所制备的介孔分子筛材料均表现了很大的比表面积(730 m2/g以上)。     

以手性两亲小分子为模板剂制备介孔二氧化硅纳米空心球

以L-亮氨酸为手性源合成了手性阳离子两亲性小分子化合物L-18Leu6NEtBr,用其自组装体作为模板,氢氧化钠为催化剂,经溶胶-凝胶过程制备出介孔二氧化硅纳米空心球;分析了介孔二氧化硅纳米空心球的尺寸和孔径.结果表明,所制备的二氧化硅空心球直径约100nm;其介孔孔道平行于壳表面,孔径为3.1nm.     

由纳米晶前驱体组装有序介孔silicalite-1分子筛（英文）

采用两步法将不同尺寸的silicalite-1分子筛纳米晶种通过自组装合成了一系列有序介孔silicalite-1分子筛.首先将强碱性的silicalite-1前驱体分别加热不同时间得到纳米晶种,然后在类似合成SBA-15的强酸性条件下组装成有序的介孔材料.合成条件的剧烈变化阻止了分子筛晶种的继续长大,并在三嵌段共聚物模板的诱导下组装成有序介孔材料.这种"自下而上"的方法制备有序介孔分子筛同时包含微孔和介孔.氮气吸脱附结果表明所制备的介孔分子筛材料均表现了很大的比表面积(730 m2/g以上).     

两亲性嵌段共聚物导向合成有序介孔金属氧化物半导体材料

有序介孔材料作为一种结构稳定、高比表面积、孔径可调、孔壁易于修饰的新型纳米结构材料在基础研究与应用开发方面都引起了人们的关注.有关有序介孔材料的文献中,无定型介孔材料(如二氧化硅、碳材料等)报道占据了大约70%,主要是由于传统软模板剂(如小分子表面活性剂或者聚环氧乙烷-b-聚环氧丙烷基嵌段共聚物)能够胜任无定型介孔材料的合成.相比而言,常规软模板剂在合成具有独特物化性能(光、电、磁以及催化、气敏等特性)的晶态半导体金属氧化物介孔材料方面面临很大的挑战.近年来,随着学科交叉发展以及高分子界研究人员加入无机多孔材料领域,一系列新型嵌段共聚物模板剂(例如具有高残碳率、高玻璃化转变温度和络合能力的嵌段共聚物)相继被合成并用于合成新型多孔材料,特别是这些模板剂在诱导组装合成有序介孔金属氧化物材料方面的研究取得了突出进展.本文从聚合物模板剂的制备与组装出发,围绕金属氧化物前驱体与模板剂之间的相互作用,系统综述了两者组装的作用机理和组装行为.深入探讨并总结了常见的三大组装方式:金属无机盐-聚合物模板、金属簇化合物-聚合物模板、金属纳米晶-聚合物模板组装,详细阐述了聚合物模板在合成有序介孔金属氧化物中的组装机理以及微观结构调控规律,并分析了聚合物模板诱导合成有序介孔金属氧化物未来宏量制备面临的机遇与挑战.鉴于其丰富的物化特性和新颖的介孔结构,有序介孔金属氧化物将逐步成为纳米光电器件、纳米催化载体以及化学传感的核心材料.     

由沸石纳米粒子自组装制备具有高催化活性中心和水热稳定的新型介孔分子筛材料

 人们合成了一系列介孔分子筛材料，并发现它们在催化、吸附与分离以及化学组装制备先进材料和分子器件等方面具有很大的潜在应用价值．但是，介孔分子筛材料相对于微孔沸石分子筛存在着两个致命弱点：较低的水热稳定性和较不活泼的催化活性中心．这两个弱点大大地影响了介孔分子筛在催化反应中的广泛应用．本文系统地综述了最近几年利用沸石纳米粒子自组装制备具有高催化活性中心和水热稳定的介孔分子筛材料的研究进展．这包括利用硅铝沸石纳米粒子自组装制备具有强酸性和水热稳定的新型介孔硅铝分子筛材料，利用钛硅沸石纳米粒子自组装制备具有高催化氧化活性中心和水热稳定的新型钛硅介孔分子筛材料，以及利用含有不同杂原子的沸石纳米粒子自组装制备一系列水热稳定的新型介孔分子筛催化材料．     

以阴离子表面活性剂/阳离子聚铵复合胶束为模板合成有序介孔二氧化硅

基于静电作用, 阴离子表面活性剂可与阳离子聚铵组装形成复合胶束. 借助阳离子聚铵,复合胶束可以作为模板与硅源协同组装, 形成高度有序的介孔二氧化硅. 本文通过调变不同种类阴离子表面活性剂、合成体系pH值、合成温度及阳离子聚铵和硅源用量等因素, 合成了具有不同介观结构和形貌的介孔二氧化硅. 实验证实阴离子表面活性剂/阳离子聚铵复合胶束模板法是合成介孔二氧化硅的一种通用方法.     

树枝状介孔二氧化硅的研究进展

介绍了树枝状介孔二氧化硅的三种合成方法,分别是微乳液合成、两相界面合成及球形胶束自组装合成法,为精确调节树枝状介孔二氧化硅的结构,探讨了不同方法可能的形成机理。由于球形胶束自组装合成法的绿色经济,重点讨论了球形胶束自组装合成法的发展及形成机理。介绍了树枝状介孔二氧化硅纳米材料在催化和生物医学方面的应用效果,并对树枝状介孔二氧化硅的合成方法和在催化、生物医学和能源领域的应用前景进行了展望。     

中空纳米二氧化硅微球的制备及表征

本文介绍了一种制备中空纳米二氧化硅微球的新方法。利用模板首先合成介孔纳米二氧化硅微球,再用水热反应法,成功制备了非功能化和巯基、氨基功能化中空纳米二氧化硅微球。利用透射电子显微镜,热重分析等手段对其形貌进行了表征。另外,对中空介孔纳米二氧化硅微球的形成机制进行了探讨。     

三维有序大孔-介孔二氧化硅的可控制备及表征

以聚甲基丙烯酸甲酯(PMMA)胶晶为大孔模板、嵌段共聚物P123为介孔模板,利用双模板剂法进行了三维有序大孔-介孔二氧化硅材料的制备研究。采用SEM、TEM、低角XRD以及N₂吸脱附技术对样品进行了表征。结果表明,通过简单的调控PMMA胶晶模板的组装过程,就可以调变合成材料中的大孔结构,从而轻松地实现可控的制备出具有网状或者层状结构的三维有序大孔-介孔二氧化硅材料,并提出了其可能的形成机理。此外,所制备的三维有序大孔-介孔二氧化硅样品均具有较大的BET比表面积(>550m₂·g^-1),大孔孔径200nm左右,介孔孔径分布集中于3.5nm左右。     

模板技术制备有序大孔含硅聚酰亚胺薄膜

以二氧化硅胶体晶体为模板，将由含硅的芳香二酐单体与芳香二胺单体在N，N-二甲基乙酰胺溶液中进行共聚得到的聚酰胺酸填入模板的空隙，经热环化，得到了二氧化硅／含硅聚酰亚胺复合物，再用氢氟酸除去二氧化硅模板，制备出了有序大孔含硅聚酰亚胺薄膜，通过扫描电子显微镜和紫外-可见光分光光度计对样品进行了表征．研究表明，所制备的含硅聚酰亚胺多孔薄膜，孔大小均匀、无收缩，在空间排布高度有序，其有序结构与模板中二氧化硅微球自组装方式完全相同，并且大孔之间由小孔互相连通．由于大孔的周期性排列，制备的薄膜表现出较好的光学特性．含硅聚酰亚胺兼具聚酰亚胺和有机硅树脂的优良性能，使制备的有序大孔薄膜在光电器件、催化、吸附、生物材料等方面具有十分重要的应用价值．     

Ordered micro/mesoporous composite prepared as thin films

A new synthesis method for preparation of thin films and powders consisting of zeolite beta nanocrystals embedded in ordered mesoporous silica matrix is described. The final structures possessing bimodal porosity, i.e., high degree of mesophase order and spatially defined microporous zeolite nanocrystals are obtained via simultaneous solvent evaporation of preformed silica/surfactant/ethanol/nanosized zeolite beta assemblies. The films were characterized with grazing-incident diffraction (GID), nitrogen sorption based on gravimetric measurements with quartz crystal microbalance (QCM) devices, and transmission electron microscopy (TEM). It is shown that the incorporation of beta nanocrystals in the mesoporous silica matrix and the mesophase order itself can be controlled through the variation of the fractional amounts of the zeolite nanoparticles and silica/surfactant solutions. The HR-TEM measurements showed that the nanosized Beta microporous crystals are separated and at the same time connected through an ordered mesostructured matrix.     

Uniform hierarchical silica film with perpendicular macroporous channels and accessible ordered mesopores for biomolecule separation

Herein, we demonstrate that silica films with perpendicular macroporous channels and accessible ordered mesopores can be conveniently prepared. The hierarchical macroporous–mesoporous silica films are synthesized by using zinc oxide nanorod array as macroporous template and CTAB surfactant as mesoporous template. In basic surfactant-containing solution, ordered mesoporous silica shells homogeneously grow on the zinc oxide nanorod array. The growth of the mesostructures do not require any chemical modification for the zinc oxide nanorod, which opens a new way for preparing hierarchical silica films with perpendicular mesochannels. The prepared hierarchical macroporous–mesoporous silica films possess a uniform thickness of 2 mm, large perpendicular macropores with a length of 1.8 mm and a width of 80 nm, and accessible ordered mesopores. Separation experiment demonstrates that this macroporous–mesoporous film can effectively separate biomolecules with different sizes.     

Preparation of amino-functionalized mesoporous silica thin films with highly ordered large pore structures

Highly ordered amino-functionalized mesoporous silica thin films have been directly synthesized by co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) in the presence of triblock copolymer Pluronic P123 surfactant species under acidic conditions by sol-gel dip-coating. The effect of the sol aging on thin films organization is systematically studied, and the optimal sol aging time is obtained. The amino-functionalized mesoporous silica thin films exhibit a long-range ordering of 2D hexagonal (p6mm) mesostructure with a large pore size of 8.3 nm, a large Brunauer–Emmett–Teller (BET) specific surface area of 680 m² g⁻¹ and a large pore volume of 1.06 cm³ g⁻¹ following surfactant extraction as demonstrated by X-ray diffraction (XRD), Transmission electron microscope (TEM), and physical adsorption techniques. Based on BET surface area and weight loss, the surface coverage of amino-groups for the amino-functionalized mesoporous silica thin films is calculated to be 3.2 amino-groups per nm². Moreover, the functionalized thin films display improved properties for immobilization of cytochrome c in comparison with pure-silica mesoporous thin films.     

Manipulation of molecular transport into mesoporous silica thin films by the infiltration of polyelectrolytes

The design of hybrid mesoporous materials incorporating polymeric assemblies as versatile functional units has become a very fertile research area offering major opportunities for controlling molecular transport through interfaces. However, the creation of such functional materials depends critically on our ability to assemble polymeric units in a predictable manner within mesopores with dimensions comparable to the size of the macromolecular blocks themselves. In this work, we describe for the first time the manipulation of the molecular transport properties of mesoporous silica thin films by the direct infiltration of polyelectrolytes into the inner environment of the 3D porous framework. The hybrid architectures were built up through the infiltration-electrostatic assembly of polyallylamine (PAH) on the mesopore silica walls, and the resulting systems were studied by a combination of experimental techniques including ellipso-porosimetry, cyclic voltammetry and X-ray photoelectron spectroscopy, among others. Our results show that the infiltration-assembly of PAH alters the intrinsic cation-permselective properties of mesoporous silica films, rendering them ion-permeable mesochannels and enabling the unrestricted diffusion of cationic and anionic species through the hybrid interfacial architecture. Contrary to what happens during the electrostatic assembly of PAH on planar silica films (quantitative charge reversal), the surface charge of the mesoporous walls is completely neutralized upon assembling the cationic PAH layer (i.e., no charge reversal occurs). We consider this work to have profound implications not only on the molecular design of multifunctional mesoporous thin films but also on understanding the predominant role of nanoconfinement effects in dictating the functional properties of polymer-inorganic hybrid nanomaterials.     

Nanoporous silica films containing aluminum and titanium

By utilizing surfactant aggregates as supramolecular templates, mesoporous and mesostructured silicas with highly ordered structures became available. The resulting mesoporous silicas are promising candidates to host various photo- and electro-active species along with catalytically active species, due to their large and controllable pore sizes, highly ordered pore arrangements with low dimensional geometries, and reactive surfaces. We have developed the rapid solvent evaporation method, which is a modified sol-gel process, for synthesizing the mesostructured silica-surfactant films as well as the mesoporous silica films. Supported thin films, self-standing films and bubbles of mesoporous silicas have been synthesized by the rapid solvent evaporation method. The microstructures of the films have also been successfully controlled by changing the synthetic conditions. Taking advantage of the ease of synthetic operation and the transparency and homogeneity of the resulting materials, we have been interested in the introduction of functional units into the mesostructured materials. This paper reports the synthesis of transparent films of titanium- and aluminum-containing nanoporous silicas to modify the surface properties (such as adsorptive and catalytic) of nanoporous silicas. The incorporation of Al led to the formation of cation exchange or acidic sites on the mesopore surface, as revealed by the cationic dye adsorption experiments. The photocatalytic reactions of the Ti-containing nanoporous silica films were also examined.     

Immobilization and electrochemistry of cytochrome c on amino-functionalized mesoporous silica thin films

The immobilization and electrochemistry of cytochrome c (cyt c) on amino-functionalized mesoporous silica thin films are described. The functionalized silica films with an Im3m cubic phase structure were deposited on conducting ITO substrate by co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) in the presence of Pluronic F127 under acidic conditions. The high specific surface area, large pore size and functional inner surface of mesoporous silica thin films result in a high cyt c loading, and the cyt c immobilization on this silicate framework is stable. After adsorption of cyt c, the ordered cubic structure of mesoporous silica and the redox activity of immobilized cyt c are retained as demonstrated by X-ray diffraction (XRD), Transmission electron microscope (TEM) and cyclic voltammetry. The redox behavior of the cyt c/silica film-modified ITO electrode is a surface-controlled quasi-reversible process for the experimental conditions used in this work and the electron transfer rate constant is calculated is 1.33 s⁻¹. The ITO electrode modified by cyt c/silica film possesses a high stability; even cyt c retains its redox activity following immobilization for several months. Furthermore, the electrocatalytic activities of the modified ITO electrode to hydrogen peroxide and ascorbic acid have been studied. Since these behaviors are quite pronounced, the modified electrode can be used for detection of hydrogen peroxide and ascorbic acid.     

Preparation of nano-sized Pt metal particles by photo-assisted deposition (PAD) on transparent Ti-containing mesoporous silica thin film

We have investigated a novel technique for the preparation of nano-sized Pt metals on Ti-containing mesoporous silica (TMS) thin film by photo-assisted deposition (PAD). The transparent TMS thin film was prepared on a quartz plate through sol—gel/spin coating. XRD, UV-Vis and Ti K-edge XAFS measurements revealed the formation of isolated Ti oxide species with a tetrahedral-coordination geometry in the silica framework. Deposition of Pt metal precursor on TMS thin film under UV-light irradiation, followed by reduction with molecular hydrogen, afforded a transparent thin film (Pt/TMS). The formation of highly dispersed nano-sized Pt metals having narrow size distributions was determined by Pd L_III-edge XANES and TEM analysis. The TMS and Pt/TMS thin films have been demonstrated to exhibit a strong hydrophilic property, even before UV irradiation, compared to the common mesoporous silica and TiO₂ thin films. After UV-light irradiation, the contact angle of water droplet on the TMS and Pt/TMS thin films became extremely lower, indicating the appearance of the photo-induced super-hydrophilic property.     

Synthesis and characterization of highly ordered functional mesoporous silica thin films with positively chargeable -NH2 groups

Highly ordered mesoporous organic-inorganic hybrid silica thin films with covalently bonded, positively chargeable -NH2 terminal groups were synthesized by evaporation induced self-assembly of tetraethoxysilane, 3-aminopropyl-triethoxysilane, and a nonionic surfactant under acid conditions and characterized using TEM, GISAXS, FTIR, SAW-based N2 sorption, and TGA.     

A Single‐Step Synthesis of Electroactive Mesoporous ProDOT‐Silica Structures

The single‐step preparation of highly ordered mesoporous silica hybrid nanocomposites with conjugated polymers was explored using a novel cationic 3,4‐propylenedioxythiophene (ProDOT) surfactant (PrS). The method does not require high‐temperature calcination or a washing procedure. The combination of self‐assembly of the silica surfactant and in situ polymerization of the ProDOT tail is responsible for creation of the mesoporosity with ultralarge pores, large pore volume, and electroactivity. As this novel material exhibits excellent textural parameters together with electrical conductivity, we believe that this could find potential applications in various fields. This novel concept of creating mesoporosity without a calcination process is a significant breakthrough in the field of mesoporous materials and the method can be further generalized as a rational preparation of various mesoporous hybrid materials having different structures and pore diameters.     

Controlling nanostructures of mesoporous silica fibers by supramolecular assembly of genetically modifiable bacteriophages

A useful virus: The synthesis of a new family of mesoporous silica fibers is reported. Monodisperse filamentous bacteriophages self-assembled into highly ordered hexagonal lattices that were used as templates for the formation of silica nanostructures. Removal of the bacteriophage assembly through calcination led to the formation of mesoporous silica fibers with pore structures precisely defined by the bacteriophage assembly (see picture).