A New Method to Study the Sol-gel Transition Process of Organic/Inorganic Hybrid Materials

The sol-gel transition process of PMMA/SiO2 hybrid materials was first studied by means of the dynamic torsional vibration method. The different stages of the transition can be described by the change of torque. The temperature-dependent measurement of the gel time（ tg ） gives the possibility to determine the apparent activation energy.（ Ea ） of this transition according to Flory＇s gelation theory. The non-equilibrium thermodynamic fluctuation theory was used to predict the transition behavior. The isothermal transition experiments on hybrid sols with different TEOS（tetraethyl orthosilicate） contents were carried out. The results show that the Ea of a hybrid sol is higher than that of a non- hybrid sol of a TEOS-water-ethanol system. The increasing of TEOS content in a hybrid sol has no obvious effect on the Ea value, but it can enhance the sol-gel .reaction rate.     

Structural, Vibrational, and Gasochromic Properties of Porous WO3 Films Templated with a Sol-Gel Organic–Inorganic Hybrid

 The structure and the gasochromic properties of sol-gel-derived WO₃ films with a monoclinic structure (m-WO₃) were studied by focusing attention on the size of the monoclinic grains. The size of the m-WO₃ grains is modified by the addition of an organic–inorganic hybrid to the initial peroxopolytungstic acid (W-PTA) sols which are based on chemically bonded poly-(propylene glycol) to triethoxysilane end-capping groups (ICS-PPG). The results obtained with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the heat treatment (500°C) of WO₃/ICS-PPG (0.5, 1, 2, 5, and 10 mol%) composite films results in a change of their morphology, and nanodimensional pores are formed between the grains. High-resolution TEM (HRTEM) analysis revealed the presence of an amorphous phase on the outside of the m-WO₃ grains, whereas energy-dispersive X-ray spectra (EDXS) showed that this amorphous phase contained W and Si. Impregnation of the WO₃/ICS-PPG film with H₂PtCl₆/i-propanol solution followed by heat treatment at 380°C gave the films their gasochromic properties. Infrared and Raman spectroscopic studies of the WO₃/ICS-PPG film confirmed the results of the corresponding HRTEM and EDXS analysis. In situ UV/Vis and in situ IR spectra of the films were measured in hydrogen and in air, and colouring/bleaching changes and the corresponding kinetics were assessed. The IR spectra of gasochromically coloured films showed that the mesoporous WO₃/ICS-PPG (1 mol%) film transforms to tetragonal H _x WO₃ bronze. The IR spectra of the H _x WO₃ bronze are discussed with the aim to establish the existence of the metal-OH vibrations of gasochromically formed oxyhydroxide tungsten bronze.     

Surface Properties of Polydimethylsiloxane-Based Inorganic/Organic Hybrid Films Deposited on Polyimide Sheets by the Sol-Gel Method

Polydimethylsiloxane (PDMS)-based inorganic/organic hybrids films were prepared on polyimide sheets by the sol-gel method using silanol-terminated PDMS and titanium tetraisopropoxide as starting materials. The effect of heat-treatment temperature on the surface property of the hybrid films was examined in terms of contact angle of water and Tapping-Mode Atomic Force Microscopy (AFM). AFM phase images showed the presence of domains, 200–500 nm in size, on the surface of these films after heat-treatment below 300°C. These regions were more hydrophilic than the rest of the area. The domains disappeared at 300°C and the surface became homogeneous surface of the peak to valley value, about 10 nm. It is also uniformly hydrophobic and a maximum contact angle (about 115°C) was obtained.     

Organic/Inorganic Hybrid Materials Based on Silsesquioxanes Derived from (3-Methacryloxypropyl) Trimethoxysilane and Their Blends with Vinylester Resins

The crosslinking of blends of a silsesquioxane (SSO) derived from (3-methacryloxypropyl) trimethoxysilane, variable amounts of a vinylester resin (VE, dimethacrylate of bisphenol A), and benzoyl peroxide (BPO) or dicumyl peroxide (DCP) as initiators, was followed by differential scanning calorimetry (DSC). For the neat SSO a thermally-initiated polymerization was observed in the 150–250°C range, leading to a conversion close to 22% of the initial C=C groups. The final conversion could be increased to a maximum value close to 83%, by adding an initiator and using a thermal cycle attaining temperatures in the range of 200°C. The use of variable amounts of VE as a co-monomer produced a slight increase of the final conversion in SSO/VE/BPO blends. Neither the conversion of double-bonds nor the addition of the VE had any effect on the onset temperature of thermal degradation, which was associated to the presence of the methacryloxypropyl groups supplied by the SSO and the VE resin. However, a distinct two-step degradation process was observed in the presence of VE. Coatings based on SSO/VE/BPO blends exhibited more uniform thicknesses and lower values of the microhardness than those devoid of VE. However, the conversion of C=C groups did not show any significant effect on the values of microhardness.     

Adsorption of Volatile Organic Compounds (VOCs) on Oxygen-rich Porous Carbon Materials Obtained from Glucose/Potassium Oxalate

To investigate the effects of oxygen-containing functional groups on the adsorption of volatile organic compounds (VOCs) with different polarity, oxygen-rich porous carbon materials (OPCs) were synthesized by heat treatment of glucose/potassium oxalate material. The carbon material had a large specific surface area (1697 m² g⁻¹) and a high oxygen content (18.95 at.%). OPC exhibited high adsorption capacity of toluene (309 mg g⁻¹) and methanol (447 mg g⁻¹). The specific surface area and total pore volume determined the adsorption capacity of toluene and methanol at the high-pressure range, while the oxygen-containing groups became the main factor affecting the methanol adsorption at the low-pressure range due to the hydrogen bond interaction through the density functional theory (DFT) calculations. This study provides an important hint for developing a novel O-doped adsorbent for the VOCs adsorption applications and analyzing the role of oxygen-containing groups in the VOCs adsorption under the low-pressure range.     

Sol-Gel技术制备二阶有机/无机复合非线性光学材料的研究进展

溶胶－凝胶技术是制备材料的一种新兴低温工艺，它为两种完全不相容的成份—聚合物材料和无机玻璃的大比例混合（或键合）创造了可能，使得制备出的材料兼备两种成份的优点。本文综述了近年来溶胶－凝胶技术在制备有机／无机复合非线性光学材料领域中的应用，并简要分析了当前研究工作所面临的问题。     

有机/无机复合介孔膜的合成及其生物酶吸附行为研究

以正硅酸四乙酯(TEOS)为硅源、三嵌段共聚物(F127)为表面活性剂, 聚碳酸酯膜为硬模板, 并采用抽滤法在聚碳酸酯膜内的亚微米级孔道中组装介孔氧化硅从而制备出有机(聚碳酸酯)/无机(介孔氧化硅)复合介孔膜. 通过扫描电镜、能量分散光谱以及透射电镜等实验表征了该有机/无机复合介孔膜的组成、结构及形貌. 研究结果表明: 通过该方法可以在聚碳酸酯膜内孔道中形成长度为9 μm、直径为200 nm的一维氧化硅棒状材料, 且该棒状材料具有无序蠕虫状和有序体心立方的混合介孔结构, 有序体心立方介孔的平均孔径约为8.5 nm. 另外, 初步考察了该复合介孔膜对生物酶的物理吸附行为, 结果表明其对肌红蛋白酶的单位吸附负载量为5.85 mg/g.     

基于溶剂原位傅克偶联反应合成杯芳烃有机多孔网络(CalixPOF)及其染料吸附特性

利用1,2-二氯乙烷(DCE)同时作为溶剂和偶联剂,通过溶剂原位傅克偶联反应合成杯芳烃有机多孔网络(CalixPOF)。采用红外光谱(FT-IR)和固体核磁碳谱(13 C-NMR)对CalixPOF的组成和分子结构进行了表征,验证了溶剂原位Friedel-Crafts偶联反应机理。采用氮气吸附、扫描电镜(SEM)、热重(TG)和紫外可见光谱(UV-vis)研究了CalixPOF的比表面积、微观结构、热稳定性和染料吸附效率等性能。结果表明:利用简单的溶剂原位傅克偶联反应可得到热稳定性良好、比表面积较大、可选择性吸附亚甲基蓝染料的CalixPOF,为自具主客体微腔的新型多孔聚合物网络的合成提供了新方法。     

Structural,Vibrational, and Gasochromic Properties of Porous WO<Subscript>3</Subscript> Films Templated with a Sol-Gel Organic–Inorganic Hybrid

Summary.  The structure and the gasochromic properties of sol-gel-derived WO₃ films with a monoclinic structure (m-WO₃) were studied by focusing attention on the size of the monoclinic grains. The size of the m-WO₃ grains is modified by the addition of an organic–inorganic hybrid to the initial peroxopolytungstic acid (W-PTA) sols which are based on chemically bonded poly-(propylene glycol) to triethoxysilane end-capping groups (ICS-PPG). The results obtained with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the heat treatment (500°C) of WO₃/ICS-PPG (0.5, 1, 2, 5, and 10 mol%) composite films results in a change of their morphology, and nanodimensional pores are formed between the grains. High-resolution TEM (HRTEM) analysis revealed the presence of an amorphous phase on the outside of the m-WO₃ grains, whereas energy-dispersive X-ray spectra (EDXS) showed that this amorphous phase contained W and Si. Impregnation of the WO₃/ICS-PPG film with H₂PtCl₆/i-propanol solution followed by heat treatment at 380°C gave the films their gasochromic properties. Infrared and Raman spectroscopic studies of the WO₃/ICS-PPG film confirmed the results of the corresponding HRTEM and EDXS analysis. In situ UV/Vis and in situ IR spectra of the films were measured in hydrogen and in air, and colouring/bleaching changes and the corresponding kinetics were assessed. The IR spectra of gasochromically coloured films showed that the mesoporous WO₃/ICS-PPG (1 mol%) film transforms to tetragonal H _x WO₃ bronze. The IR spectra of the H _x WO₃ bronze are discussed with the aim to establish the existence of the metal-OH vibrations of gasochromically formed oxyhydroxide tungsten bronze. Received October 4, 2001. Accepted (revised) November 19, 2001     

An Explosive Organic／Inorganic Hybrid： Synthesis and Thermal Property of Octa （2,4-dinitrophenyl） silsesquioxane

Octaphenylsilsesquioxane (OPhS) was prepared by a modifying method and a new core-shell nanocomposite, octa(2,4-dinitrophenyt)sitsesquioxane, [(R2PhSiO1.5)8, R=-NO2, ODNPhS], was synthesized by nitration of OPhS in a mixed acid solution of nitric and sulfuric acids at about 60℃. Their molecular structures were determined by DRIFTS, ^1H NMR, ^13C NMR spectra analysis. The thermal analysis shows that ODNPhS is an explosive that detonates at about 420℃.     

On the Energetics of nh3 Adsorption and Decomposition on nb(100) Surface : a ubi-qep Study

The energetics of the adsorption and decomposition of ammonia on Nb(100) surface was investigated by the method of unity bond index-quadratic exponential potential (UBI-QEP). The experimental as well as theoretically derived atomic heats of adsorptions were used as the input data and the results were compared with the findings of local density functional theory (LDFT) and non-local density functional theory (NLDFT). The method was capable of correctly predicting the fragmentation of ammonia on 4-fold hollow sites on the surface of Nb(100) and magnitudes of the heats of adsorptions and activation energies were more realistic.     

CO在SnO2(110)面吸附特性的密度泛函研究

根据密度泛函理论, 采用广义密度近似和总体能量平面波赝势方法, 以6层Slab周期结构为模型, 计算了CO以4种不同方式在SnO2(110)表面的吸附, 研究了CO吸附对表面特性的影响. 计算结果表明, CO以C端向下在低配位Sn5C位置的顶位吸附为稳定的吸附方式, 该吸附对表面的驰豫现象有所改善. CO吸附并未明显改变表面电子态密度分布, 但造成了费米能1.06 eV的升高. 吸附后CO分子向表面转移了0.07个电子, 使表面电阻下降. 理论计算的结果支持了气体传感器气敏机理中的表面电导模型.     

A Soft Copper(II) Porous Coordination Polymer with Unprecedented Aqua Bridge and Selective Adsorption Properties

Herein, the synthesis, crystal structure, and full characterization of a new soft porous coordination polymer (PCP) of ([Cu₂(dmcapz)₂(OH₂)]DMF_1.5)_n ( 1 ) formulation, which is easily obtained in the reaction of CuX₂ (X=Cl, NO₃) salts with 3,5‐dimethyl‐4‐carboxypyrazole (H₂dmcapz) is present. Compound 1 shows a copper(II) dinuclear secondary building unit (SBU), which is supported by two pyrazolate bridges and an unprecedented H₂O bridge. The dinuclear SBUs are further bridged by the carboxylate ligands to build a diamondoid porous network. The structural transformations taking place in 1 framework upon guest removal/uptake has been studied in detail. Indeed, the removal of the bridging water molecules gives rise to a metastable evacuated phase ( 1 b ) that transforms into an extremely stable porous material ( 1 c ) after freezing at liquid‐nitrogen temperature. The soaking of 1 c into water allows the complete and instantaneous recover of the water‐exchanged material ( 1 a′ ). Remarkably, 1 b and 1 c materials possess structural bistability, which results in the switchable adsorptive functions. Therefore, the gas‐adsorption properties of both materials have been studied by means of single‐component gas adsorption isotherms as well as by variable‐temperature pulse‐gas chromatography. Both materials present permanent porosity and selective gas‐adsorption properties towards a variety of gases and vapors of environmental and industrial interest. Moreover, the flexible nature of the coordination network and the presence of highly active convergent open metal sites confer on these materials intriguing gas‐adsorption properties with guest‐triggered framework‐breathing phenomena being observed. The plasticity of Cu^II metal center and its ability to form stable complexes with different coordination numbers is at the origin of the structural transformations and the selective‐adsorption properties of the studied materials.     

Morphology‐Controlled Self‐Assembly of an Organic/Inorganic Hybrid Porphyrin Derivative Containing Polyhedral Oligomeric Silsesquioxane (POSS)

An organic/inorganic hybrid porphyrin derivative, namely, metal‐free tetrakisphenyl porphyrin–polyhedral oligomeric silsesquioxanes (H₂TPP‐POSS) was synthesized by azide–alkyne click chemistry. The self‐assembly behavior of H₂TPP‐POSS was systematically studied in CHCl₃ at different concentrations and in solvents with different polarities. Novel nanovesicles could be obtained through the self‐assembly of H₂TPP‐POSS in CHCl₃ at a concentration lower than 10^?4 m. Diffuse microrods formed at a concentration higher than 10^?4 M . Additionally, the polarity of the solvent also greatly influenced the assembled morphologies, and a series of assembled morphologies, including crescent‐shaped micelles, spherical micelles, doughnut‐shaped vesicles, and ordered square sheets, could form in solvents with different polarities.     

Photophysical Properties of a Novel Organic–Inorganic Hybrid Material: Eu(III)-β-Diketone Complex Covalently Bonded to SiO2/ZnO Composite Matrix

In this article, dibenzoylmethane (DBM) was first grafted with the coupling reagent 3-(triethoxysilyl)-propyl isocyanate (TESPIC) to form precursor DBM–Si, and ZnO quantum dot was modified with 3-mercaptopropyltrimethoxysilane (MPS) to form SiO₂/ZnO nanocomposite particle. Then the precursor DBM–Si and the terminal ligand 1,10-phenthroline (phen) were coordinated to Eu³⁺ion to obtain ternary hybrid material phen–Eu–DBM–SiO₂/ZnO after hydrolysis and copolycondensation between the tetraethoxysilane (TEOS), water molecules and the SiO₂/ZnO network via the sol–gel process. In addition, for comparison, the binary hybrid material with SiO₂/ZnO network and ternary hybrid material with pure Si–O network were also synthesized, denoted as Eu–DBM–SiO₂/ZnO and phen–Eu–DBM–Si, respectively. The results reveal that hybrid material with SiO₂/ZnO network phen–Eu–DBM–SiO₂/ZnO exhibits the stronger red light, the longer lifetimes and higher quantum efficiency than hybrid material with pure Si–O network phen–Eu–DBM–Si, suggesting that SiO₂/ZnO is a favorable host matrix for the luminescence of rare earth complexes.     

石英晶体微天平技术研究纳米TiO2表面Cu(Ⅱ)吸附与光化学还原过程

The adsorption and photochemical reduction process of Cu(Ⅱ) at the surface of nanocrystalline TiO₂ was investigated using in situ quartz crystal microbalance(QCM). It was found that the adsorption of Cu(Ⅱ) onto active sites of nanocrystalline fit the pseudo-second-order reaction better than the pseudo-first-order reaction, and that the rate constant of the reaction was estimated to be about 0.09 g·mmol₂·min₂. In addition, it was also found that the adsorption amount of Cu(Ⅱ) at the surface of TiO₂ was affected by pH、concentration and coexisting anions, and the saturated amount of adsorbed Cu(Ⅱ) was approximately 1.5 mmol·g^-1 at pH 4. During UV illumination, the frequency of QCM decreased gradually, which meant the photoreduction deposition of Cu(Ⅱ) from the solution, moreover, the rate of photodeposition of Cu(Ⅱ) increased with increasing pH of solution, and the rate of photoreduction enhanced obviously when the organics were introduced.     

石英晶体微天平技术研究纳米TiO_2表面Cu(Ⅱ)吸附与光化学还原过程

环境中排放的重金属离子Cu!对水生和陆生生物有强的毒害性。饮用水中Cu!的浓度高于1.0mg·L-1时,将会导致人畜得血色沉着病和胃肠粘膜病[1]。Cu!无法进行生物降解,除去废水中Cu!的常见方法有离子交换、置换、化学沉淀等[2],然而这些方法需要消耗大量的化学试剂,成本高。近来,研     

Synthesis and Optical Properties of Europium‐Complex‐Doped Inorganic/Organic Hybrid Materials Built from Oxo–Hydroxo Organotin Nano Building Blocks

Hybrid materials doped with novel europium complexes were synthesized using PMMA‐co‐Sn₁₂Clusters (copolymers from oxohydroxo‐organotin dimethacrylate and methylmethacrylate) as the matrix material. Two types of hybrid materials were obtained: the physically doped product, PMMA‐co‐Sn₁₂Cluster/Eu(TTA)₃phen, and the grafted product, PMMA‐co‐Sn₁₂Cluster‐co‐[EuAA(TTA)₂phen] (TTA=2‐thenoyltrifluoroacetone, phen=phenanthroline and AA=acrylic acid). The hybrid materials exhibited characteristic luminescence of the Eu³⁺ ions, and also showed relative especial optical properties compared with samples just using PMMA as the matrix material. The PMMA‐co‐Sn₁₂Cluster matrix exhibited a high physical doping quantity of [Eu(TTA)₃phen], which can be attributed to the special structure of this kind of hybrid material. GPC (gel‐permeation chromatography), TGA (thermogravimetric analysis), SEM, ¹H NMR, ICP (inductively coupled plasma), ¹¹⁹Sn NMR, FTIR, and diffuse reflectance techniques were employed to characterize the structures and properties of these hybrid materials.     

Simple Organic Salts Having a Naphthalenediimide (NDI) Core Display Multifunctional Properties: Gelation,Anticancer and Semiconducting Properties

Following a supramolecular synthon rationale, a dicarboxylic acid derivative having a naphthalenediimide (NDI) core, namely, bis‐N‐carboxymethyl naphthalenediimide ( NDI‐G ), was reacted with n‐alkyl amines with varying alkyl chain lengths to generate a new series of primary ammonium dicarboxylate (PAD) salts. The majority of the salts (≈85 %) were found to gel various polar solvents. The gels were characterized by dynamic rheology and high‐resolution electron microscopy. Single‐crystal and powder X‐ray diffraction analyses were used to study the supramolecular synthon present in one of the gelator salts (i.e., S8 ). Charge‐transfer (CT)‐induced gelation with donor molecules such as anthracene methanol ( Ant ) and pyrene ( Py ) was also possible with S8 . The CT complex ( S8.Ant ) displayed anticancer activity as probed by cell migration assay on the highly aggresive breast cancer cell line MDA‐MB‐231 . The DMSO gel of S8.Ant also displayed semiconducting behavior. To the best of our knowledge, simple organic salts with an NDI core that display such mulitifunctional properties are hitherto unknown.