Perfluoropolyether-Silica Hybrids: Preparation and Surface Characterization

,-Triethoxysilane terminated perfluoropolyether-polycaprolactone block copolymers, TXCL(x)Si, were synthesised, characterised and subsequently reacted with tetraethoxysilane to prepare transparent organic-inorganic hybrid materials by using the sol–gel process. Surface characterization was carried out through contact angle measurements. All the materials investigated (independently on both the reaction time of the sol–gel reaction before coating application and the bulk organic-inorganic ratio) showed a strong hydrophobic character when compared with non-fluorinated and fully inorganic control materials. The highest water contact angles were obtained when TXCL(x)Si oligomer used for the preparation of the hybrid contained short hydrogenated polycaprolactone segments. In all cases, the surface tension values indicated that the very surface at the air-coating interface showed almost completely perfluoropolyether segments.     

Synthesis of Highly Porous Organic/Inorganic Hybrids by Ambient Pressure Sol-Gel Processing

This paper reports the synthesis of highly porous organic/inorganic hybrids by a two-step acid-base catalyzed sol-gel process and ambient pressure drying. In the method organic and inorganic precursors are copolymerized so as to incorporate organic ligands into the solid network. The two-step acid-base catalyzed process was used to prevent phase segregation during the hydrolysis and co-condensation of organic and inorganic precursors. The organic ligands incorporated into the solid gel network modify the surface chemistry. Thus, the wetting angle is significantly increased so that the collapse of the gel network is greatly reduced upon the removal of pore fluid during drying. Organic/inorganic hybrids with BET surface areas above 1250 m2/g, porosities above 75% and pore sizes of 8 nm have been synthesized.     

Syntheses and Characterizations of Two New Organic-inorganic Hybrids Based on Heteropolymolybdates and Piperidine Molecules

1 INTRODUCTION The rational design and synthesis of organic-inor- ganic hybrid materials have recently attracted an increasing interest not only from a structural point of view, but also due to their potential applications in different areas such as catalysis, medicine, sorption, electrical conductivity, magnetism and photoche- mistry[1~8]. It should be noted that polyoxometalates (POMs)[9~11], known as their wide applications in many interdisciplinary fields, are an outstanding class o…     

Biomimetic Processing of Gel Glasses and Organic-Inorganic Hybrids

Biological hard tissues like bone and shell show combinations of strength and toughness that are hard to duplicate with synthetic materials. These properties are attained by a composite of organic and inorganic phases with very organized microstructures. The structures are hierarchical in that several different scales of organization contribute to the final properties.Biological systems form by chemical precipitation at room temperature in contrast to synthetic processing, which usually depends on thermal solidification. In principle, chemical solidification can give much more control over composition and structure but is limited by the time taken for diffusion processes in any solid component.A family of solid freeform fabrication methods have recently been developed which allow parts to be built under the direct control of a 3-dimensional CAD drawing without the need for a mold. These methods also offer a way of building composite structures, with full control of structure and composition at the scale of 100 m and up. Since this is a layerwise process, like biological growth, diffusion paths are short and so chemical processing of large parts is feasible.We have been developing an SFF system based on extrusion of a reactive slurry through a 300 m needle. The needle is moved on three axes so as to build up a part. The application of this method to the formation of components from sol-gel glasses and organic-inorganic hybrids is described.     

Non-Conventional Curing of Organic-Inorganic Hybrids

Infrared and microwave curing of organic–inorganic hybrid materials was studied, in order to achieve the maximum conversion without detrimental effects due to the overheating or to the long-time permanence at high temperature. Partially cured poly(ethylene oxide)/silica hybrids were prepared by hydrolysis and subsequent condensation of precursors for 30 minutes isothermal heat treatment at 70°C. The conversion after the preliminary treatment is still low and requires an additional heating to complete the reaction. Three different thermal treatments were investigated: conventional heating, infrared heating and microwave heating. DSC characterisation of the obtained samples evidenced a drastic reduction of the treatment time when microwaves were used, requiring only a few seconds, compared to the hours-lasting conventional treatments.     

Ceramers Based on Crosslinked Epoxy Resins-Silica Hybrids: Low Surface Energy Systems

Ceramers based on silica and bisphenol-A epoxy resin cured with methyl nadic anhydride (MNA) and diamino diphenyl sulphone (DDS) were prepared in THF solutions. Compatibilization was induced through functionalization of the epoxy resin with amine trialkoxy silanes prior to mixing with a pre-hydrolyzed tetralkoxysilane solution (TEOS).The epoxy ceramers were further modified by the addition of small amounts of a silane functionalized alkane perfluoroether oligomer.A morphology consisting of very fine interpenetrating phases could be easily achieved through the silane functionalization of the epoxy resin. The final ceramer, however, always displayed a reduction in the glass transition temperature (Tg), resulting either from reactions of the anhydride hardener with the ethanol produced from the hydrolysis of TEOS or from the reaction of the acid catalyst with the epoxy groups.The use of the perfluoroether oligomer produced a large reduction in surface energy due to migration of the fluorinated components to the outer layers of the films.     

Lignin-Silica-Titania Hybrids as Precursors for Si–Ti–C–O Fibers

Lignin-silica-titania and lignin-titania hybrid fibers have been prepared by sol-gel processing from lignin, tetraethoxysilane, and titanium tetrakis(2,4-pentanedionate) using a mixture of 2,4-pentanedione and tetrahydrofuran as solvent and H2SO4 as catalyst. Amounts of H2O and H2SO4, to add to the solutions with the Si-to-Ti atomic ratios of 0–1.0, were determined for achieving favorable spinnability of fibers from the solutions. The FT-IR spectrum of the fibers indicated the formation of hybrid fibers. The hybrid fibers, cured in air to avoid coalescense, could be converted into Si–Ti–C and TiC fibers upon pyrolysis at 1500°C in Ar.     

纳米粒子—温度响应型共聚物复合材料*

本文根据构成复合材料中聚合物上侧链基团的不同,分别介绍异丙基丙烯酰胺、乙烯基醚和乙烯基吡啶三大类典型的温度响应型共聚物的主要性质及其与无机纳米粒子复合后形成的有机-无机复合材料的结构特点和温度响应行为。另外,对此类复合材料在可控相转移催化的应用中进行了详细地介绍,并对该复合材料未来的发展前景进行了展望。     

Tailor–made Covalent Organic‐Inorganic Polyoxometalate Hybrids: Versatile Platforms for the Elaboration of Functional Molecular Architectures

Post‐functionalization of organically modified polyoxometalates (POMs) is a powerful synthetic tool to devise functional building blocks for the rational elaboration of POM‐based molecular materials. In this personal account we focus on iodoaryl‐terminated POM platforms, describe reliable routes to the synthesis of covalent organic‐inorganic POM‐based hybrids and their integration into advanced molecular architectures or multi‐scale assemblies as well as their immobilization onto surfaces. Valorisation of the remarkable redox properties of POMs in the fields of artificial synthesis and molecular electronic is especially considered.     

Michael Addition Reaction of Fluorinated Nitro Compounds

The Michael addition reactions of fluorinated nitro compounds with electron deficient olefins to give γ‐fluoro‐γ‐nitro‐esters, nitriles and ketones which bear a fluorinated quaternary carbon center were reported. The reactions were promoted by TMG, affording the desired adducts in acceptable to good yields.     

氟代糖的合成

本文综述了氟代糖合成的新进展及利用选择性氟化合成具有生物活性的物质。     

Monitoring of the Sol-Gel Synthesis of Organic-inorganic Hybrids by FTIR Transmission,FTIR/ATR,NIR and Raman Spectroscopy

Summary: The sol-gel synthesis of organic-inorganic hybrids based on triethoxysilane- terminated poly(ethylene oxide) and tetraethylorthosilicate was monitored in-situ using three spectroscopic methods (FTIR/ATR, Raman, NIR). These spectroscopic methods allow in-situ monitoring of the evolution of hybrid materials starting from the modification of the polymer and the early steps of hydrolysis up to the network formation. By application of ²⁹Si solid-state NMR spectroscopy the assignment and quantification of the Raman bands to different end groups and different cross-linking states was made. The sol-gel reaction was also followed by in-line NIR spectroscopy. A multivariate data analysis was accomplished to obtain a conversion-time curve. Furthermore, we investigated spin-coated films on wafers using FTIR transmission spectroscopy.     

含氟液晶研究进展

本文简述了含氟液晶的研究进展。根据小分子含氟液晶中氟原子或含氟基团的位置不同,将其分为3类：末端是氟原子或含氟基团的液晶、苯环上氢原子被氟原子取代的液晶、中心桥键上的氢原子被氟原子取代的液晶。根据小分子含氟液晶特点,归纳了氟原子或含氟基团对液晶分子物理性质的影响。同时对高分子含氟液晶的研究进展也做了介绍。     

反离子对氟表面活性剂的影响1. 表面活性及胶团化作用

通过表面张力和荧光探针法研究了全氟辛酸钠、全氟辛酸铵以及全氟辛酸四烷基铵[C₇F₁₅COON(C_nH_2n+1)₄, n＝1, 2, 3, 4]的表面活性以及胶团化作用, 系统地讨论了各种反离子, 特别是反离子大小的影响. 结果表明, 与普通碳氢表面活性剂不同, 反离子对这类氟表面活性剂的表面活性以及胶团化作用有很大影响. 表面活性剂的临界胶束浓度(cmc)随反离子的增大而下降; 饱和吸附层中平均每个分子所占的面积则大致随反离子的增大而增大. 而表面张力的变化则较为复杂. cmc时的表面张力随反离子的增大先上升(从全氟辛酸铵到全氟辛酸四乙铵)后下降(从全氟辛酸四乙铵到全氟辛酸四丁铵). 通过反离子的空间位阻、疏水性、插入以及电荷屏蔽效应对上述结果做了解释.     

氟改性聚氨酯乳液的合成及其表面性能

氟改性聚氨酯乳液的合成及其表面性能;氟改性;聚氨酯乳液;表面性能     

Hybrid Organic-Inorganic Materials by Nonhydrolytic Sol-Gel Processes: Organosilsesquioxane-Metal Oxide Hybrids

Organosilsesquioxane-metal oxide hybrid materials prepared by the Sol-Gel process are mainly heterogeneous. In this paper we report the preparation of methylsilsesquioxane-titanium oxide, and methylsilsesquioxane-aluminium oxide hybrid materials by a nonhydrolytic sol-gel process involving the etherolysis-condensation of a mixture of methyltrichlorosilane and metal chloride. The Si/M ration in the xerogels were very closed to the one of the starting solutions. ²⁹Si MAS NMR study has revealed that the methylsilsesquioxane-titanium oxide xerogel was heterogeneous at the atomic level. The spectrum of the hybrid containing aluminium, has shown beside a peak at –66 ppm corresponding to MeSi(OSi)₃ environment, another peak at –47 ppm which was ascribed to MeSi(OAl)₃ environment. The presence of only these two sites might be due to their stability.     

镍催化氟代烯基硼酯与烷基卤化物Suzuki偶联反应

有机化合物特定位点嵌入氟原子或含氟片段,可以产生独特的生物或物理性质改变.单氟取代烯基是生物医药领域理想的酰胺键替代物,在医药化学、药物研发等方向已经获得广泛的应用.通过溴化镍（Ⅱ）二乙二醇二甲醚复合物、4,4'-二叔丁基-2,2'-二吡啶的催化体系,实现了多种氟代烯基硼酯与一级烷基卤化物碘代物、溴代物以及二级烷基溴代物的Suzuki偶联反应.该反应具有良好的收率和优秀的官能团兼容性,能够兼容酯基、氰基、醇羟基等多种具有有机合成化学价值的官能团,为单氟取代烯烃的合成提供了方法.机理实验表明该反应可能经历烷基卤化物自由基均裂历程.     

几个新型含氟化合物的合成

以3-硝基-4-氯三氟甲苯(1)为起始原料, 合成了新型含氟杂环化合物8和3个含氟中间体4, 5, 6. 通过IR, NMR, MS和元素分析对它们的结构进行了表征. 探讨了反应条件对产物结构的影响, 提出了化合物4可能的形成机理.     

功能模板导向的自组装合成介孔结构有机／无机复合材料

回顾了近年来硅基介孔材料有机功能化的基本方法和研究进展．基于作者的相关研究工作,着重介绍一种新型的介孔氧化硅有机功能化的方法——功能模板导向的自组装法,阐述了该方法在自组装合成新型有机／无机复合材料方面的应用．     

Fluorinated polyimide nanocomposites for CO2/CH4 separation

The purpose of this project was to synthesize fluorinated polyimide (PI) nanocomposite membranes in order to study the gas permeation rates and selectivity of carbon dioxide and methane. PIs were synthesized from 2,2‐bis(3,4‐anhydrodicarboxyphenyl)hexafluoropropane (6F dianhydride, 6FDA) and 4,4′‐diaminodiphenyl ether (oxydianiline, ODA) into which were incorporated nanoparticulate additives as follows: in situ TiO_2, both plain and treated with dodecyl sulfate surfactant, and organo‐clay (Cloisite®‐10 Å) at loads of 1, 3, and 5 wt% to the polyamic acid. Polyamic acid films were solvent cast, cured at 200°C then post‐cured at 300°C and measured for permeation data and for thermal properties. Glass transition temperatures ranged from 124 to 140°C for the cured PIs and from 142 to 147°C for the post‐cured materials, the nano‐inclusions having little discernable effect on this property. Thermogravimetric analysis (TGA) data show that the inclusion of Cloisite® or TiO₂ caused a small decrease of thermal stability from 555°C to about 532 to 541°C. The inclusion of clay causes a decreased permeation rate while the addition of TiO₂ improves the rate and selectivity. Treating the nanofillers with surfactant decreases selectivity and marginally increases rate of permeation of CO₂. Post‐curing caused a darkening of the composites, but not the neat PI. This heat treatment also resulted in a significantly decreased permeation rate, but a significantly increased selectivity. The resulting material shows superior gas separation properties to the commercially available PI, Matrimid® produced by Ciba‐Geigy. Copyright © 2008 John Wiley & Sons, Ltd.