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.     

低自由能固体表面的制备及其应用*

低自由能表面具有一些独特的性能,在工业和日常生活中具有广泛的应用,本文就低自由能表面的制备及其发展概况进行综述,共引用文献83篇。     

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…     

聚四氟乙烯、有机硅复合改性聚氨酯/环氧树脂共混聚合物的合成及其低表面能特性

以甲苯-2,4-二异氰酸酯(TDI)、聚醚二元醇为主要原料制得—NCO封端的预聚体,按一定比例和环氧树脂E-51混合均匀;另用氨乙基氨丙基甲基二甲氧基硅烷、八甲基环四硅氧烷(D4)合成一系列分子量不同的氨基聚硅氧烷,用多元胺作固化剂,并以聚四氟乙烯(PTFE)粉末为填料,合成一系列由PTFE、有机硅共同改性的聚氨酯/环氧树脂共混聚合物。测试了其力学性能、表面接触角、吸水率,同时进行了扫描电镜(SEM)以及表面电子能谱(ESCA)分析。结果表明:所制得的共混聚合物具有很低的表面能和良好的综合性能,PTFE和氨基聚硅氧烷对降低聚氨酯/环氧体系的表面能具有明显的复合效应。     

低表面能侧基含氟聚合物*

含氟聚合物材料具有优异的热稳定性、极低的表面能、强化学稳定性和生物相容性等,在功能涂料、织物整理、微电子、汽车以及航空航天等领域具有很好的应用前景。本文综述了侧基含氟聚合物的主链、全氟烷基链、主链与全氟烷基链段间连接基团的结构对聚合物表面性能的影响,并总结了环境友好型低表面能侧基含氟聚合物的研究进展。     

Hybrid Organic-Inorganic Sol-Gel Materials Based on Epoxy-Amine Systems

Understanding the synthesis-structure-properties relationship of hybrid organic-inorganic materials is an important and fundamental task to develop a new generation of highly performing systems for the new needs of nanotechnologies. This issue is, also, important to improve the properties of hybrids when used in applications where nanoscale control is not a fundamental request. In this article, a short overview of epoxy amine sol-gel hybrids is reported. The synthesis of these materials has a large flexibility to allow the fabrication of a wide group of hybrids with different structures and properties, whose applications are ranging from non-linear optics to adhesive and protective coatings.     

低表面能化合物在超浸润材料中的应用

近年来,由于超浸润材料在自清洁、微流体传输和生物相容性等方面的潜在应用,具有极端润湿性的超浸润材料成为了材料领域的一个研究热点。研究表明,除材料表面微纳米结构的构筑外,材料表面能的控制也是制备超浸润材料的另一关键因素。随着对超浸润材料润湿性机理研究的深入,许多不同结构不同类型的低表面能化合物也越来越多地被应用于超浸润材料的制备中。本文从分子结构、化合物类型等角度出发,综述了超浸润材料制备中所大量应用的低表面能化合物,并归纳了pH值、温度、浓度及溶剂等因素对材料低表面能化的影响,总结了低表面能化合物在提高机械强度、制备润湿性转换材料和不同浸润性修饰中的选择和应用情况,最后提出了低表面能化合物应用的一些不足之处并对其发展方向进行了展望。     

Fluorinated 2-Vinylcyclopropane Copolymers as Low Surface Energy Materials

The surface structure and surface energy properties of fluorinated 2-vinylcyclopropane copolymers were investigated. The copolymers were prepared by free radical ring opening polymerization of fluorinated 1 and non-fluorinated 2 2-vinylcyclopropanes. NEXAFS experiments proved that the film surface was ordered with the fluorinated side groups possessing a relatively high orientational order. Contact angle measurements with different interrogating liquids permitted the polymer surface tension to be estimated. These surfaces showed both hydrophobic and oleophobic character, consistent with a low surface energy.     

有机氟改性环氧树脂的研究进展

利用有机氟改性环氧树脂是提高环氧树脂综合性能的有效途径。目前含氟环氧树脂已经成为学者研究的重点。文章扼要综述了有机氟对改善环氧树脂的表面性能、耐热性能、介电性能、耐摩擦性能及阻燃性能的最新研究进展。展望了有机氟改性环氧树脂的发展趋势。     

具有低表面能的改性淀粉纳米晶的制备

通过端异氰酸酯基与淀粉纳米晶表面的部分羟基反应,引入聚二甲基硅氧烷分子,制备表面能低、分散稳定的改性淀粉纳米晶。通过红外光谱(FT-IR)、核磁共振氢谱(1 H-NMR)、光电子能谱(XPS)、X射线衍射仪(XRD)、扫描电镜(SEM)等对其结构和形貌进行表征。结果表明,低表面能有机硅分子和二苯甲基二异氰酸酯反应到淀粉纳米晶上,其纳米颗粒粒径为50~100nm,分散均匀。此外,浸润性实验表明,改性淀粉纳米晶在水、二氯甲烷、乙酸乙酯、丙酮中分散稳定。     

Theoretical Studies on the Potential Energy Surface and Vibrational Energy Levels of HXeBr

The potential energy surface for the electronic ground state of the HXeBr molecule is constructed from more than 4200 ab initio points calculated using the internally contracted multi-reference configuration interaction method with the Davidson correction （icMRCI ＋ Q）. The stabilities and dissociation barriers are identified from the potential energy surface. The three-body dissociation channel is found to be the dominant dissociation channel for HXeBr. Low-lying vibrational energy levels of HXeBr calculated using the Lanczos algorithm are found to be in good agreement with the available experimental band origins.     

聚醚接枝聚硅氧烷共聚物改进环氧树脂表面性能的研究

共混改性;形态;聚醚接枝聚硅氧烷共聚物改进环氧树脂表面性能的研究     

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.     

Modification of Polymer Substrates with Low Surface Free Energy Material by Low‐Temperature Cured Polybenzoxazine

The B‐ala/AIBN PBZ system has a high extent of ring‐opening of oxazine because phenol‐containing oligomers are formed at the early stage of the curing process. As a result, the B‐ala/AIBN PBZ system possesses a relatively stronger intramolecular hydrogen bonding and lower surface energy than the pure B‐ala system at low temperature curing. In this context, poly(4‐vinyl pyridine), poly(4‐vinyl phenol) thin films and polycarbonate substrates, which lack liquid resistance, possess low surface free energy after modification with B‐ala/AIBN = 5/1 PBZ.

     

Determination of Activation Energy for Glass Transition of an Epoxy Adhesive Using Dynamic Mechanical Analysis

The activation energy associated with the glass transition relaxation of an epoxy system has been determined by using the three-point bending clamp provided in the recently introduced TA Instruments DMA 2980 dynamic mechanical analyzer. A mathematical expression showing the dependency of modulus measurements on the sample properties and test conditions has also been derived. The experimental results showed that the evaluation of activation energy is affected by the heating rate and test frequency, as well as the criterion by which the glass transition temperature (T _g) is established. It has been found that the activation energy based on the loss tangent (tanδ) peak is more reliable than on the loss modulus (E ₂) peak, as long as the dynamic test conditions do not cause excessive thermal lags. This revised version was published online in August 2006 with corrections to the Cover Date.     

Water-Mediated Epoxy/Surface Adhesion: Understanding the Interphase Region

Epoxy resins coatings are commonly found in corrosion protection coatings but the presence of water can affect their adhesion to the substrate, often weakening the adhesion of the coating to the solid, reducing its efficiency. Nevertheless, small amounts of water can enhance the epoxy/substrate interactions. In this work, the interphase region of an epoxy precursor and metal oxide substrates is investigated using molecular simulations and it is found that water accumulates between the epoxy layer and the solid substrate. At high water concentrations (9 wt %) the interaction between the epoxy precursor and the solid surface is weakened regardless of the nature of the solid, but at low water concentrations the nature of the solid surface becomes important. For hematite, the presence of water decreases the strength of adhesion but for goethite the presence of a small amount of water (3 wt %) enhances the adhesion to the surface resulting in a densification at the interface.     

Surface Energy of Silica-TEOS-PDMS Ormosils

Inverse gas chromatography (IGC) was applied to characterize the surface energy of organically modified silicates (ormosils) by measuring the interaction of molecular organic probes with the ormosil surface. Ormosils were prepared by the sol-gel method by the reaction of TEOS (tetraethoxysilane), PDMS (polydimethylsiloxane) and different types of silica (Aerosil 130, Aerosil 200 and Aerosil 380). The isosteric heat of adsorption, q _st, and the dispersive component of the surface energy, _s ^D, were estimated by using the retention volume of different nonpolar and polar probes at infinite dilution. The dispersive component shows an increase as the specific surface area of the silica is increased from 29.6 mJ/m² to 51.4 mJ/m² at 60°C. Such values are lower than that obtained for aerosil particles meaning that PDMS chains impede the interaction with silanol groups located on the silica surface. The specific interaction parameter, I^SP, and the enthalpy of specific adsorption, H _a ^SP, of polar probes on the ormosil surface were also measured in order to obtain the acid-base character of ormosil surface. The H _a ^SP, was correlated with the donor, DN, and the acceptor, AN, numbers of the probes to quantify the acidic, K _A, and the basic, K _B, parameters of the substrate surface. The obtained results suggest that the silica particles were covered by PDMS chains in a different way depending on the type of silica used. The values of K _A and K _B suggest that the ormosil surface is amphoteric, with predominantly acceptor electron sites.     

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.     

化学改性环氧树脂水基涂料的研究——涂膜性能

用对氨基苯甲酸改性环氧树脂 ,使其具有亲水亲油两亲性质 ,测定了改性产物和纯环氧树脂共混物的玻璃化转变温度 ,结果显示两者能够相容 ,并以改性产物及其与纯环氧树脂的混合物制备水基涂料 ,测定了涂膜的物理和化学性能。结果表明 ,涂膜性能优良 ,保持了溶剂型环氧涂料的抗冲击强度、光泽度和硬度等方面的优点 ,而附着力提高 ,同时柔韧性大为改善 ,涂膜耐水性和耐化学药品性能优良。