Synthesis and thermal characterization of hafnium polythioethers

Hafnium polythioethers were synthesized utilizing both the aqueous solution and interfacial condensation techniques. Synthesis is general and fairly rapid being complete within 1 min.

Several products exhibit reasonably good weight retention (70% at 1000°C) but all show poor low temperature stabilities with degradation beginning about 100°C. Initial degradation to ～250°C is via an internal non-oxidative pathway where as degradation at higher temperatures occurs via an oxidative mode in air.     

Synthesis of zirconium polyethers

The synthesis via interfacial and aqueous solution techniques of zirconium polyethers has been accomplished: Polymer yield seeks a maximum around a molar ratio of Cp₂ZrCl₂: Diol: Base of 1:1:2.     

Synthesis of oligomeric group IVA ferrocene polyesters

Oligomeric Group IVA ferrocene Polyesters were synthesized utilizing the interfacial condensation technique. Yield decreases with increasing complexity of the aliphatic substituent; it decreases in the order of I > Br > Cl, and it decreases in the order of Sn > Ge > Si. Thus, initial attack by the nucleophile, steric requirements, and metal—halide bond breakage appear important: Where M = Si, Ge, or Sn.     

锆氧杂环配合物的合成研究

合成了2个新型茂锆络合物,经过BBr3作用生成2个锆氧杂环络合物。4个新络合物经元素分析、核磁共振、质谱确证结构。     

八乙烯基多面体低聚倍半硅氧烷的合成与表征

采用水解缩合法,在浓HCl为催化剂的条件下,以乙烯基三甲氧基硅烷为原料合成了八乙烯基多面体低聚倍半硅氧烷,并对合成产物进行了表征;研究了反应温度、反应物的投料比对产物收率的影响.结果表明,在25 ℃,反应物水解缩合21 d,乙烯基三甲氧硅烷、HCl、CH3OH三者的体积比为9∶ 12∶ 200,乙烯基三甲氧基硅烷、HCl的体积分数分别为3.90%、5.43%时,产物的收率达到最高,为26.3%.     

Synthesis and characterization of zirconium silicalite-1

Zirconium silicalite-1 (ZS-1) catalysts with MFI structure were prepared using a hydrothermal synthesis method. XRD, SEM, IR,²⁹Si MAS NMR, UV-VIS DRS, physical adsorption of nitrogen, and elemental analysis were then performed to evaluate its physico-chemical properties, and evidences of Zr⁴⁺ incorporation into the zeolite framework were provided : The unit cell volume of zirconium silicalite-1 increased linearly with increases in zirconium content, and the characteristic framework i.r. spectra shifted to lower frequencies as Zr⁴⁺ was incorporated into the silicalite-1 lattice. For its catalytic reaction test, liquid phase 2-butanol oxidation using hydrogen peroxide as an oxidant was carried out. All of the zirconium silicalite-1 samples synthesized were active for the 2-butanol oxidation, but activities obtained using ZS-1 catalysts were lower than TS-1 catalyst. Zirconium in the zeolite frameworkwas found to be the active site for the 2-butanol oxidation.     

Synthesis and characterization of near monodisperse oligomeric polystyrenes

Oligomeric (<10³) polystyrenes have been synthesized on a practical scale by the use of secbutyllithium and triethylamine in cyclohexane. These samples were found to possess relatively narrow molecular weight distributions. The product analysis was accomplished by viscosity, vapour pressure osmometry, gel permeation chromatography and gas chromatography.     

Longitudinal acoustic vibrations in polyethers and polythioethers

A search has been made for polymers which exhibit in their Raman spectra bands originating in longitudinal acoustic vibrations. Features have been found in a range of poly(alkylene ethers) and poly-thioethers. It appears that if relatively extended runs of CH₂CH₂ units separate the chalcogenide atoms, the polymers vibrate similarly to polyethylene. Hence, the Raman method can be used in identifying and estimating the thickness of lamellae in these cases.     

Synthesis and characterization of zirconium ionomer dispersions

Water-based ionomer dispersions were formed by post-polymerization addition of zirconium species to polymer latices prepared from butyl methacrylate (BMA), butyl acrylate (BA) and acrylic acid (AA) by semicontinuous emulsion polymerization. The mole fraction of AA in the latex particles was kept at 10 mole% in all cases whereas the ratio of BA to BMA was varied. A method was established which allowed zirconium in the form of ammonium zirconium carbonate (AZC) to be successfully introduced into the latices without affecting their colloidal stability. Dynamic light scattering was used to determine average particle size in diluted latices. The structure and properties of cast ionomer films were investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), tensile strength and swelling measurements. Fourier transform infrared spectroscopy (FTIR) was used to investigate the nature of the carboxylate bonding.     

笼形八乙烯基聚硅倍半氧烷的制备和表征

比较了制备八乙烯基聚硅倍半氧烷的三种酸性水解工艺。结果发现，两步水解法无论是从环保、节能和产率方面考虑，还是从产品提纯上考虑都是较理想的方法。通过IR、^29Si NMR、^1H NMR、飞行质谱及元素分析法判断，所制备的产物为八乙烯基硅倍半氧烷，与文献报道数据相吻合。产物为六面体晶体，晶胞参数为a=b=1．63nm，c=1．72nm。产物在质量损失率为5％时的温度为265．4℃，在650℃时的残余质量分数为2．8％。     

Synthesis and flash sintering of zirconium nitride powder

Zirconium nitride (ZrN) is a transition metal nitride of great interest due to its excellent physical and chemical properties. This study aims to synthesize ZrN fine powders by a facile and low-cost urea route that avoids the use of any solvent. ZrCl₄ and urea mixtures were heat-treated at up to 1600˚C in nitrogen gas. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The effects of different processing parameters such as metal to urea molar ratio, heat treatment temperature, and dwelling time on the product phase and stoichiometry were studied to understand the synthesis method. In addition, synthesized ZrN powder was consolidated into near fully dense single-phase bulk ceramic with a homemade flash sintering setup. A constant DC electrical field of ∼80 V/cm and pressure of ∼14 MPa at room temperature triggered flash sintering without pre-heating, and the entire process finished in 200 s. The composition, microstructure, density, hardness, and oxidation properties of the sintered pellet were also characterized.     

Synthesis and properties of a liquid oligomeric cyanate ester resin

A multiple aromatic ether-containing cyanate ester resin system with high thermal stability and superb processability has been developed. The oligomeric monomer was prepared via a hydroxyl-terminated intermediate synthesized from a modified Ullmann synthesis with bisphenol A and 1,3-dibromobenzene in the presence of potassium carbonate and a catalytic amount of a copper (I) complex in N,N-dimethylformamide. The hydroxyl-terminated intermediate was end-capped with the cyanate moiety by reaction with cyanogen bromide and triethylamine in dry acetone resulting in a resinous material at ambient temperatures. The thermo-oxidative and water absorption properties were determined for the new cyanate ester polymer as well as its flexural strength, flexural modulus and Rockwell hardness. Mechanical tests were also conducted on the commercially available 2,2′-bis(4-cyanatophenyl)isopropylidene cyanate ester resin to investigate the effect of introducing an oligomeric spacer between the terminal end groups on the properties of the material.     

Synthesis and characterization of polyhedral oligomeric azido‐octaphenylsilsesquioxane

Polyhedral oligomeric azido‐octaphenylsilsesquioxane (N₃‐OPS) was synthesized from octaaminophenylsilsesquioxane (OAPS) via its diazonium salt. The synthesis included nitration of octaphenylsilsesquioxane (OPS) to octanitrophenylsilsesquioxane (ONPS), conversion of ONPS into octaaminophenylsilsesquioxane (OAPS), and conversion of OAPS into N₃‐OPS. The kinetics of the conversion of OAPS into N₃‐OPS were studied by recording the volume of N₂ gas released with the reaction time, which revealed it to be a 1st order reaction. The chemical structures of ONPS, OAPS and N₃‐OPS were characterized by ¹H‐NMR, GPC, FTIR, ²⁹Si solid NMR, ¹³C‐NMR, XRD, and elemental analysis. It is proposed that the diazonium salt of OAPS was substituted by the main ? N₃ group and a few of the ? OH groups. The ratio of ? N₃:? OH was calculated to be approximately 68:32 in N₃‐OPS on the basis of the elemental analysis and ¹H‐NMR. XRD suggested that N₃‐OPS was a kind of amorphous compound. The two‐step conversion mechanism of OAPS to N₃‐OPS was briefly discussed. TGA results showed that N₃‐OPS was stable at ambient temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of polyhedral oligomeric silsesquioxane-based waterborne polyurethane nanocomposites

A series of aqueous polyurethane nanocomposites were prepared using various amounts (0.3-4.6 wt%) of a diol functionalized polyhedral oligomeric silsesquioxane (POSS) by the prepolymer mixing method. N,N-bis(2-hydroxy ethyl-2-amino ethane sulfonic acid sodium salt (BES sodium salt) was used as the anionic internal emulsifier and ionic center. The molecular structure of the samples was characterized by ATR-FTIR spectroscopy. We investigated the effect of the POSS contents on the properties of the specimens by particle size and viscosity measurements, X-ray diffractometry, mechanical behavior assessment, dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis and morphological studies. The results showed that with increasing the POSS contents, particle size, viscosity, tensile strength, modulus, T _g , and thermal stability of the synthesized samples were improved. Also, SEM and TEM images indicated that a homogeneous morphology was obtained in the 1.2 wt% POSS-based sample. AFM results showed that the surface roughness increased as the POSS amounts increased.     

Synthesis and properties of polynorbornenes bearing oligomeric siloxane pendant groups

The ring-opening metathesis polymerization (ROMP) of norbornene derivatives 1-5 bearing oligomeric siloxane pendant groups was carried out with Grubbs 1st and 2nd generation, and Grubbs-Hoveyda ruthenium (Ru) catalysts. Monomer 1 gave high-molecular-weight polymers (M_n ca. 27?000-180?000) in high yields (80-100%). Monomers 2-5 also polymerized with Ru carbene catalysts to give high-molecular-weight polymers (M_n ca. 34?000-240?000) in high yields (66-100%). The onset temperatures of weight loss (T₀) of the polymers were 180-250 °C. The glass transition temperatures (T_gs) of poly(1) and poly(2) bearing branched siloxane linkages were near or higher than room temperature (27 and 101 °C). Meanwhile, the T_gs of poly(3)-poly(5) bearing linear siloxane linkages were much lower (−115 to −23 °C), and decreased with increasing length of the siloxane linkages. Poly(1) and poly(2) were hydrogenated completely, which was confirmed by ¹H NMR spectroscopy. The free-standing membranes of poly(1) and poly(2) showed high gas permeability; especially poly(2) is the most permeable to various gases among ROMP-polynorbornene derivatives reported so far.     

Synthesis and characterization of polyimide/oligomeric methylsilsesquioxane hybrid films

In this study, polyimide/silsesquioxane hybrid materials were synthesized from aminoalkoxysilane‐capped poly(pyromellitic dianhydride‐co‐4,4′‐oxydianiline) (PMDA‐ODA) and oligomeric methylsilsesquioxane (O‐MSSQ) precursors. The O‐MSSQ moiety was used to obtain well characterized nano‐inorganic cage and network structures in the hybrid materials. The effects of molecular structures and composition on the morphologies and properties of the prepared hybrid materials were studied. The phase separation of the prepared hybrid materials could be controlled by varying the molecular weight of the polyimide moiety, the Si? OH end group content of the O‐MSSQ or the coupling agent. Homogeneous and transparent hybrid thin films were obtained from the low molecular weight polyimide moiety with a coupling agent, 3‐aminopropyltrimethoxysilane (APrTMS). However, microphase separation occurred if the molecular weight of the polyimide moiety was enhanced or was prepared without a coupling agent, as evidenced by atomic force microscopy (AFM), field emission scanning electron microscopy (FE‐SEM), and electron spectroscopy for chemical analysis (ESCA). The high Si? OH content of the O‐MSSQ could enhance the bonding density between the organic and inorganic moiety and thus retard phase separation. The thermal and mechanical properties of the prepared hybrid materials were largely improved compared with the parent polyimide, PMDA‐ODA, and were demonstrated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermal‐stress analysis. The hybrid materials showed adjustable refractive index and dielectric constant by varying the O‐MSSQ content. The birefringence of the PMDA‐ODA was reduced by incorporating the O‐MSSQ moiety. This work revealed that the polyimide/O‐MSSQ hybrid materials could have potential applications as optical films or low dielectric constant materials. Copyright © 2004 Society of Chemical Industry     

纳米级二氧化锆粉体的合成及性能测试

以廉价无机盐氧氯化锆为原料，用氨水作沉淀剂，采用溶胶一凝胶法制备纳米级二氧化锆结合XRD和TEM等测试手段进行表征，并考察了二氧化锆的制备机理及此类氧化物的结构特点。     

Synthesis,characterization, and properties of a polyhedral oligomeric octadiphenylsulfonylsilsesquioxane

A novel polyhedral oligomeric octadiphenylsulfonylsilsesquioxane (ODPSS) was synthesized from octaphenylsilsesquioxane and benzenesulfonyl chloride via a Friedel–Crafts reaction with a high yield. ODPSS was identified by Fourier transform infrared spectroscopy, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI–TOF MS), wide‐angle X‐ray diffraction, and elemental analysis to be a kind of polyhedral oligomeric silsesquioxane of a T₈R₈ structure. ODPSS exhibited superior thermal stability according to thermogravimetric analysis. Its initial thermal decomposition temperature (T_onset) was at 491°C in air and 515°C in nitrogen. Thermal and mechanical properties of epoxy resin (EP) composites with ODPSS added were studied by differential scanning calorimetry and tensile testing. The results show that the incorporation of ODPSS at a low loading content not only improved the glass‐transition temperature of the EP composites but also enhanced their tensile strength. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40892.     

氨丙基低聚硅倍半氧烷及其酰胺化产物的合成与表征

由3-氨基丙基三甲氧基硅烷（NH₂-propyl-silane）出发,在碱催化条件下采用水解缩合一锅法合成了笼形氨丙基硅倍半氧烷（NH₂-propyl-POSS）。红外光谱、核磁共振、电喷雾飞行质谱（ESI-TOF）表征结果表明,合成产物NH₂-propyl-POSS是不同大小笼形结构的混合物,其中T8、T9、T10笼形结构含量较高。由NH₂-propyl-POSS分别与乙酸和丙炔酸进行酰胺化反应,进一步合成了乙酰基丙基POSS（CH₃-CONH-POSS）和丙炔酰基丙基POSS（CH≡C—CONH-POSS）,并通过红外光谱、氢谱、碳谱分析表征了其结构。X射线衍射分析结果表明,3种POSS均为非晶态结构。通过热重分析可知,NH₂-propyl-POSS具有较高的热稳定性。将NH₂-propyl-POSS用于提高环氧树脂（EP）的热稳定性,添加量为5 %（质量分数,下同）时,EP/NH₂-propyl-POSS共混物的玻璃化转变温度（T_g）提高至180.7 ℃,极限氧指数（LOI）为25.2 %。     

Synthesis of zirconium and hafnium germanates from mechanically activated oxides

The peculiarities of the synthesis of zirconium and hafnium germanates (ZrGeO₄ and HfGeO₄) from mechanically activated oxides (GeO₂, ZrO₂ and HfO₂) have been studied. The phase, structural and morphological evolutions of the products obtained by thermal treatment of mechanically activated oxides were studied by a set of analytical techniques. The results showed a significant decrease in GeO₂ crystallite size during mechanical treatment, whereas the size of HfO₂ and ZrO₂ changes only slightly. Mechanical treatment of mixtures results in great change of morphology, an increase in particles contact area and partial amorphization of GeO₂. Mechanical activation promotes a significant reduction of the temperature of compound formation, reaction rate and yield. Possible mechanisms of activation effect are discussed.