Complexation of Titanium Alkoxides with Cis-2-butene-1,4-diol and Hydrolysis of Their Products

Reaction of Ti(OEt)₄ and Ti(OBu ⁿ )₄ with cis-2-butene-1,4-diol (B.diol-2H) in 1:1 molar ratio was studied at room temperature using the sol-gel process. ¹³C{¹H}- and ¹H-NMR data showed that all the B.diol-2H completely reacted with both titanium alkoxides. Each of the products was hydrolyzed by water. The new hydrolyzed products were characterized by ¹³C- and ¹H-NMR spectroscopy and Karl–Fischer Titration. Thermogravimetric and differential thermal analyses (TGA-DTA) of the hydrolyzed-products were also studied.     

2-甲基-2-戊烯酸的合成与应用研究

以丙醛为起始原料,经羟醛缩合反应和空气氧化反应合成了2-甲基-2-戊烯酸,研究了2-甲基-2-戊烯酸在香精方面的应用。用该工艺合成的产品纯度高,香气好,具有较高的工业应用价值。     

Cost efficient preparation of lead aminoalkoxides directly from lead(II) oxide

The preparation of lead(II) aminoalkoxides has been demonstrated from the direct reaction of aminoalcohols with lead(II) oxide. The denticity of the aminoalcohols determined the facility of the reactions, the rate increasing with the number of hydroxyls. Thus, [Pb(dmae)₂], 1, [Pb(mdea)]_∞, 2, and [Pb(teaH)]₂, 3 (dmaeH = dimethylaminoethanol, mdeaH₂ = N-methyldiethanolamine, and teaH₃ = triethanolamine) have been prepared in high yields and characterized by ¹H and ¹³C NMR. The X-ray crystal structure analyses of 2 and 3 are described.     

Complexation of Titanium Alkoxides with Cis-2-butene-1,4-diol and Hydrolysis of Their Products

Reaction of Ti(OEt)₄ and Ti(OBu ⁿ )₄ with cis-2-butene-1,4-diol (B.diol-2H) in 1:1 molar ratio was studied at room temperature using the sol-gel process. ¹³C{¹H}- and ¹H-NMR data showed that all the B.diol-2H completely reacted with both titanium alkoxides. Each of the products was hydrolyzed by water. The new hydrolyzed products were characterized by ¹³C- and ¹H-NMR spectroscopy and Karl–Fischer Titration. Thermogravimetric and differential thermal analyses (TGA-DTA) of the hydrolyzed-products were also studied.     

醇盐锆水解制备ZrO2粉体的研究

选用实验室合成的醇盐锆为前驱体，采用ｓｏｌ－ｇｅｌ工艺制备了氧化锆粉体。利用ＴＥＤ、ＤＴＡ、ＸＲＤ、ＩＲ光谱等手段研究了水解过程及水解产物的热处理过程，若适当控制醇盐锆水解条件，可制成亚微米级分布均匀的超细粉体。     

三溴偶氮胂光度法测定对苯二甲酸中微量锆

研究了显色剂三溴偶氮胂与锆的显色反应.在1.2 mol·L-1 HCl溶液中,锆与三溴偶氮胂反应形成蓝色配合物,最大吸收波长为640 nm,表观摩尔吸光系数为5.0×104L·mol-1·cm-1.25 mL溶液中,锆含量在0～20 μg范围内符合比尔定律.将该方法用于对苯二甲酸中微量锆的直接测定,相对标准偏差为1.6%～3.7%,加标回收率为98%～102%,结果令人满意.     

Zirconium tetra-n-butylate modified with different organic acids: Hydrolysis and polymerization of the products

In this work, (a) complexation reaction of zirconium tetra-n-butylate, Zr(OBu ⁿ )₄, with MAc and different organic acids, (b) the hydrolysis reaction of modified Zr species, and (c) the polymerization reaction of complex products are studied. Zr(OBu ⁿ )₄ was reacted with different mole ratios of methacrylic acid (MAc) at room temperature and the maximum combination ratio was found to be 1:2 [Zr(OBu ⁿ )₄:MAc] by FT-IR. The modification of zirconium tetra-n-butylate with the acid mixtures [methacrylic acid-acetic acid (MeCOOH), methacrylic acid-propionic acid (EtCOOH), methacrylic acid-butyric acid (PrCOOH)] was made for a combination ratio of 1:1:1 [MAc:RCOOH:Zr(OBu ⁿ )₄; R: Me, Et, Pr] and the products were characterized by¹H-NMR, FT-IR, and UV spectroscopies. Following their synthesis, hydrolysis of the complexes with various amounts of water and polymerization with benzoyl peroxide were realized. The hydrolysis and polymerization products of the complexes were studied by Karl-Fischer coulometric titration and thermal analysis, respectively. Methyl ethyl ketone(MEK) and chloroform were chosen as solvents.     

Crystalline BaTiO3 synthesis by ultrasound and microwave‐assisted sol–gel process

Highly crystalline BaTiO₃ particles were prepared by sol–gel process. Ultrasound and microwave techniques were used to facilitate the synthesis of BaTiO₃. BaTiO₃ samples were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), particle size analyser, and high temperature differential scanning calorimetry/thermogravimetric analysis (DSC/TGA). The results indicate that both barium and titanium sources and preparation techniques affected BaTiO₃ purity and crystallite size. The smallest particle and crystallite sizes were obtained by using BaCl₂ and (C₄H₉O)₄Ti and the crystallite size of BaTiO₃ was 8 ± 1 nm via MW technique.     

Zirconium tetra-n-butylate modified with different organic acids: Hydrolysis and polymerization of the products

In this work; (a) complexation reaction of zirconium tetra-n-butylate, Zr(OBu ⁿ )₄, with MAc and different organic acids. (b) the hydrolysis reaction of modified Zr species, and (c) the polymerization reaction of complex products are studied. Zr(OBu ⁿ )₄ was reacted with different mole ratios of methacrylic acid (MAc) at room temperature and the maximum combination ratio was found to be 12 [Zr(OBu ⁿ )₄MAc] by FT IR. The modification of zirconium tetra-n-butylate with the acid mixtures [methacrylic acid-acetic acid (MeCOOH), methacrylic acid-propionic acid (EtCOOH), methacrylic acidbutyric acid (PrCOOH)] was made for a combination ratio of 111 [MAcRCOOHZr(OBu ⁿ )₄RMe. Et, Pr] and the products were characterized by¹H-NMR, FT-IR, and UV-spectroscopies. Following their synthesis, hydrolysis of the complexes with various amounts of water and polymerization with benzoyl peroxide were realized. The hydrolysis and polymerization products of the complexes were studied by Karl-Fischer Coulometric titration and thermal analysis respectively. Methyl-ethyl-ketone (MEK) and chloroform were chosen as solvents.     

Precisely Controlling Preparation of Ceria‐Stabilized Zirconia Microspheres of ~100 μm by External Gelation

Ceria‐stabilized zirconia (CSZ) microspheres of ~100 μm were prepared by external gelation process. The inner diameter of nozzle was 0.2 mm. The key process parameters including broth pH value, Zr concentration, flow rate, and vibration frequency were optimized for precise control of the diameter. The optimum parameters were found to be flow rate of 11.08 mL/min, Zr concentration of 0.72 mol/L, and vibration frequency of 2650 Hz. CSZ microspheres with an average diameter of 103.1 μm and standard deviation of 4.4 were prepared under these conditions. CSZ microspheres showed good monodispersity, good sphericity, and high density.     

The Effect of α‐Zirconium Phosphate Nanosheets on Thermal,Mechanical, and Tribological Properties of Polyimide

In this work, to investigate the addition effect of 2D α‐zirconium phosphate (α‐ZrP) nanosheets on the properties of polyimide (PI), a series of PI/ZrP composites are synthesized by in situ polymerization. The thermal, mechanical, and tribological properties of composites strongly depend on the dispersity and distribution of α‐ZrP nanosheets in the PI matrix. The dispersed α‐ZrP can make rich interfacial interactions with PI matrix, which facilitates the transfer of external stress, heat, antiwear ability, etc., from the PI matrix to the surface of the α‐ZrP nanosheets, leading to the obvious enhancements of the thermal, mechanical, and tribological properties of the PI/ZrP composites. Specially, compared with pure PI, the tensile strength and elongation at break of the optimum sample of PI‐0.6 are increased by 13.7% and 35.7%, while its wear volume is reduced by 85%. This work provides a new paradigm for using other layered 2D nanosheets to prepare high‐performance PI‐based composite materials.     

Synthesis of proton conductive membranes based on inorganic–organic hybrid structure bound with phosphonic acid

Proton conductive inorganic–organic hybrid membranes were synthesized from styrene derivatives of alkoxysilane and ethyl 2-[3-(dihydroxyphosphonyl)-2-oxopropyl] acrylate (EPA) through copolymerization followed by sol–gel reaction. Self-standing, homogeneous and transparent hybrid membranes with chemically bound phosphonic acid groups were synthesized. FT-IR analysis exhibited the hybrid membranes included phosphonic acid groups. ¹³C and ²⁹Si NMR studies indicated that alkoxysilyl functionalized styrene derivatives were not only copolymerized with EPA but also condensed yielding Si–O–Si linkages by sol–gel reaction. TG–DTA analysis revealed that these membranes were thermally stable up to 200 °C in dry O₂. The proton conductivities of the hybrid membranes increased with phosphonic acid content and temperature. The P/Si ratio of the membrane was dependent on the number of alkoxy group in the starting alkoxysilane. The hybrid membrane from (dimethylmethoxysilylmethyl)styrene (DMMSMS(M))/EPA = 1/6 revealed proton conductivities of 6.3 × 10⁻³ and 2.4 × 10⁻⁴ S cm⁻¹ at 68.0% relative humidity and 18.8% relative humidity, respectively, at 140 °C.     

Sol–gel derived organic/inorganic hybrid gels based on poly(2-hydroxyethyl aspartamide) and silica

The sol–gel derived polymer/silicate hybrid materials have attracted considerable attention in recent years. The incorporation of silicate phase into polymeric materials may constitute an important tool to either enhance mechanical properties or provide more biocompatibility to the resulting hybrids. PHEA, α,β-poly(N-2-hydroxyethyl-dl-aspartamide), is a class of poly(amino acid)s that has been widely studied as a biodegradable functional polymer with potential biomedical and pharmaceutical applications. Hydrogels from PHEA are formed easily by a chemical or physical crosslinking reaction but the resulting gels are mechanically weak and less thermally stable. In this study, hybrid materials were prepared based on PHEA and silicate. A sol–gel process was employed using TEOS and modified PHEA to introduce inorganic silicate phase within the polymer gel matrix. FT-IR and NMR were used to analyze the chemical structure of the PHEA derivatives. In addition, the morphology, thermal and swelling properties of the hybrid gels were examined.     

Hybrid Network Sulfonated Polynorbornene/Silica Membranes with Enhanced Proton Conductivity by Doped Phosphotungstic Acid

A series of novel hybrid sulfonated polynorbornene‐silica (PBN–SiO₂) proton conducting membranes doped with different weight ratio of phosphotungstic acid (PWA) were prepared by the casting procedure. The proton conductivity of the composite membranes containing 40 wt.% PWA reached the maximum of 6.1 × 10^–2 S cm^–1 and increased gradually with PWA content and temperature elevating, while the methanol permeabilities (3.52–9.39 × 10^–7 cm² s^–1) of these membranes were much lower than that of Nafion 117 (2.36 × 10^–6 cm² s^–1). The membranes also exhibited excellent thermally stable and mechanical properties, which imply that the PBN–SiO₂–PWA membranes are promising materials in the direct methanol fuel cells (DMFC) applications.     

吲哚丙酮酸的制备新工艺

以吲哚为原料,通过甲酰化、缩合和水解反应制备得到吲哚丙酮酸,并对反应条件进行了选择和优化。以三乙胺为催化剂、水为溶剂,确定反应时间2．Sh、反应温度110℃、底物浓度2mol·L-1,缩合产率可这81．5％;调节水解用碱比例为5:1、水解温度110℃、底物浓度0．5mol·L-1、反应时间2h,在氯气保护条件下水解产率达到92％。     

Synthesis of highly active nanocrystalline WO3 and its application in laser-induced photocatalytic removal of a dye from water

Tungsten oxide nanoparticles were synthesized using the sol–gel process and applied for heterogeneous photocatalytic removal of a dye using a 355 nm laser radiation generated from Nd:YAG for the first time. Effect of various parameters, such as calcination temperature, calcination time, catalyst concentration and laser energy on the photocatalytic removal of dye has been investigated. The study showed that almost complete degradation of dye can be achieved within very short time of reaction (within few minutes) in presence of nanocrystalline WO₃ under laser irradiation. The removal process obeys first-order kinetics with an appreciable rate constant 0.146 min⁻¹. The main reason of high efficiency is the nanostructure nature of WO₃ and the laser as an excitation source as compared with the conventional setups using lamps and conventional microstructure catalysts.     

Preparation of templated mesoporous silica membranes on macroporous α-alumina supports via direct coating of thixotropic polymeric sols

A simple method for depositing mesoporous silica films directly on macroporous α-alumina supports is reported. A polymeric silica sol was prepared by hydrolysis of tetraethylorthosilicate in acid propanol in presence of hexadecyltrimethylammonium bromide as template. The rheology of the sol was changed by a modified urea-based thixotropic agent, which was used in a concentration range between 2% and 10% on volume. The dynamic viscosity of the sol was measured as a function of shear rate. The rheology modifier was found to increase the viscosity of the sol and confer at the same time a thixotropic behavior to it. Long range order in the unmodified and modified materials was analyzed by XRD on powders after calcination at 500 °C. It was found that the pore size increased with increasing concentration of additive, while the degree of order decreased until eventually, at high concentrations, the ordered porous structure collapsed completely. The gradual pore size increase at lower concentration is thought to be caused by swelling of the surfactant micelles by the rheology modifier.The modified sols were deposited via dip-coating on α-alumina disks. The morphology of the silica top layers was characterized by SEM. Pore size distributions and permeances of the prepared membranes were assessed by permporometry and single gas permeation measurements, respectively. The membranes had narrow pore size distributions, with an average diameter of about 2 nm. Permeabilities of H₂, He, CH₄ and O₂ were compared. Hydrogen permeances up to 6 × 10⁻⁷ mol s⁻¹ m⁻² Pa⁻¹ were measured at 473 K. The gas flux across the membrane follows a Knudsen-type mechanism, as shown by the permselectivities.     

Relation between the scratch resistance and the chemical structure of organic–inorganic hybrid coatings

Organic–inorganic hybrid materials can be defined as materials combining organic and inorganic domains in a nanometric scale. The development of these organic–inorganic hybrids has achieved properties from both organic and inorganic materials.     

Synthesis and characterization of mesoporous materials: Silica–zirconia and silica–titania

An experimental strategy was developed to obtain mesoporous SiO₂–ZrO₂ and SiO₂–TiO₂ mixed oxides by a sol–gel method, treating the gels hydrothermally. The solids were characterized by nitrogen physisorption, pyridine thermodesorption, ²⁹Si nuclear magnetic resonance, SEM and X-ray diffraction. The effects of ZrO₂ content, the generated pressure in the synthesis vessel and further modification of this type of procedure on the solids properties were studied. It was found that SiO₂–ZrO₂ and SiO₂–TiO₂ mixed oxides dried at atmospheric pressure developed type I isotherms. On the other hand, for the SiO₂–ZrO₂ and SiO₂–TiO₂ mixed oxides that were treated under pressure in the autoclave (at high SiO₂ content) the porosity was improved and mesoporous materials exhibiting type IV adsorption isotherms. Specific surface area and pore size distribution were a function of ZrO₂ and TiO₂ content. The materials exhibited narrow pore size distributions with pore diameters in the region of mesopores at about 4 nm and high surface areas, the highest being 481 m²/g for the 10 wt% ZrO₂ Si–Zr material. Differences in acidity as determined by pyridine thermodesorption were observed to depend on the synthesis parameters and ZrO₂ and TiO₂ concentration.     

In-Situ Catalyst Generation and Controlled Hydrolysis in the Sol–Gel Precipitation of Zirconia and Titania Particles in Poly(dimethylsiloxane)

The usual sol–gel hydrolysis-condensation technique for the in-situ generation of reinforcing silica particles within an elastomer was recently modified by (i) controlling the required water of hydrolysis by simply absorbing it from the air, and (ii) generating the required catalyst in-situ from a tin salt. In the case of the silica, which is generated in poly(dimethylsiloxane) (PDMS), the technique had the advantages of producing well dispersed, highly reinforcing particles that did not significantly reduce the transparency of the composite. Applying the new technique to the in-situ generation of zirconia and titania in the same polymer also gave small well-dispersed particles, good reinforcement, and improved thermal stability. Although transparency was not maintained as well as in the case of the controlled hydrolysis producing silica, it was definitely better than that of composites prepared by the usual excess water method.