Characterization and thermal degradation studies on polyaniline‐intercalated montmorillonite nanocomposites prepared by a solvent‐free mechanochemical route

Polyaniline (PANI)‐montmorillonite (MMT) nanocomposites were prepared by direct intercalation of aniline molecules into MMT galleries, followed by in situ polymerization within the nano‐interlamellar spaces under solvent‐free conditions. The basal spacing of aniline‐intercalated MMT increased gradually up to 1.5 nm with increasing amounts of aniline loaded. This result suggests that aniline molecules were adsorbed by MMT clay and that intercalated aniline likely located perpendicular to the silicate sheets. After polymerization, X‐ray diffraction and Fourier transform infrared analyses confirmed the successful synthesis of PANI chains between the MMT nano‐interlayers. The scanning electron microscopy images indicated that the surface morphologies of PANI–MMTs were strongly different depending on the PANI content. The electrical conductivities of PANI nanocomposite particles in pressed pellets ranged in the order of between 10^?3 and 10^?2 S/cm. UV–vis spectroscopy and doping level measurement were further used to discuss the conductivities of nanocomposites. The thermal stabilities of PANI–MMT nanocomposites were examined by using thermogravimetric‐differential thermal analysis and derivative thermogravimetric analysis, and both analyses consequently demonstrated the improved thermal stabilities of the PANI chains in the nanocomposites as compared to pure PANI. The thermal stabilities of resulting nanocomposites were strongly related to the PANI content, which increased as the PANI content decreased in the nanocomposites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2705–2714, 2005     

Solid-state mechanochemical synthesis of cobalt(III), iron(III), and chromium(III) bisdicarbollyl complexes

Thallous dicarbollide reacts with cobalt(II), iron(III) and chromium(III) chlorides without a solvent under conditions of mechanical activation to form the corresponding carborane complexes of tervalent metals. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1715–1717, October, 1993.     

Iron(iii) chloride-catalyzed mechanochemical cascade synthesis of highly-substituted pyrrolyl indoles

Iron(iii) chloride has been found to serve as an efficient catalyst for a mechanochemical (ball milling) one-pot four- component cascade reaction of phenyl glyoxal, anilines, indoles and activated alkyne affording highly-substituted 3-(1H-pyrrol-2-yl)-1H-indoles. The procedure is beneficial because of mild conditions, easily available starting materials, cheap catalyst and possibility for scaling.     

Solid-state mechanochemical synthesis of tris(4-imino-2-pentanonato)chromium,Cr[CH3C(NH)CHC(O)CH3]3

Tris(4-imino-2-pentanonato)chromium was prepared by solid-state synthesis under conditions of mechanical activation of a mixture of chromium(III) chloride and sodium 4-imino-2-pentanonate and characterized by IR spectroscopy, X-ray diffraction, and electronic absorption spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2227–2229, December, 1994.The present work was carried out as a part of Project No. 1.164 Mechanochemical Synthesis of Complex Compounds of The State Scientific and Technical Program Ecologically Safe Processes in Chemistry and Chemical Technology with the financial support of the Ministry of Science of the RF.     

About the synthesis and thermal stability of SiO2-aerogel

Aerogels are extremely porous high-tech materials based on inorganic oxides, especially silica. The paper describes synthesis and properties of SiO₂-aerogel, and changes occurring during heating of SiO₂-aerogel in the temperature range from 20 to 1000°C. Four thermoanalytical methods were used: Thermodilatometry, Differential thermal analysis, Thermogravimetry and Derivative thermogravimetry.     

一种双钒帽多金属氧酸盐的水热合成及其晶体结构和热稳定性

采用水热法合成了一种双钒帽多金属氧酸盐[CrⅢ(1,10-phen)2(H2O)]2[PMoⅤ6MoⅥ6O40(VⅣO)2(OH)];利用元素分析、红外光谱、单晶X射线衍射表征了其组成和分子结构,利用热重分析测定了其热稳定性.结果表明,合成的化合物由无序的双帽假Keggin型[PMoⅤ6MoⅥ6O40(VⅣO)2(OH)]6-杂多阴离子和两个[CrⅢ(1,10-phen)2(H2O)]3+配位阳离子单元组成,其热失重分两步进行,热稳定性良好.     

Fe2O3-ZrO2层柱蒙脱石的合成和热稳定性

蒙脱石是具有2∶1层状结构的粘土矿物,酸化蒙脱石用途广泛[1]。利用较大体积多聚金属阳离子与蒙脱石进行离子交换并把蒙脱石层撑开,可以得到复合材料—层柱蒙脱石(ＰＩＬＭ),它具有二维的层柱结构,其孔径比一般的分子筛大。其孔径还可以根据蒙脱石离子交换当量和交换阳离子的体积大小加以控制。它具有良好的热稳定性和酸性,并且合成方法简单。蒙脱石和膨润土在我国分布广泛,储量大。因此ＰＩＬＭ在载体、吸附剂及较大分子转化催化剂等方面具有较好的应用前景。传统的层柱蒙脱石是由单组分多聚金属阳离子与蒙脱石进行交联而合成的,本文在…     

热分解法制备的Co/SiO2催化剂上费-托合成反应性能

以无定形二氧化硅为载体,分别采用浸渍法和热分解法制备了钴基催化剂Co/A200-I和Co/A200-D,采用TG、XRD、TEM和TPR等手段对其进行了表征,并考察了这些催化剂在费-托合成反应中的性能。结果表明,浸渍法制备的Co/A200-I催化剂中钴颗粒没有规则的形状,但却具有较高的费-托合成反应活性;热分解法制备的Co/A200-D催化剂中钴颗粒呈一种球形二次结构,直径比较均匀,对于费-托合成反应具有较高的轻质烃选择性。此外,载体比表面积对催化剂结构也有较大的影响;相对于Co/A200-D催化剂,Co/A380-D催化剂的载体比表面积较大,这使得金属-载体间的相互作用较强而较难还原,但还原后Co/A380-D催化剂拥有较高的钴分散度和较好的反应活性     

Glass forming ability and thermal stability of oxyfluoride glasses

New oxyfluoride glasses based on the system ZrO₂-Pr₂O₃-ZrF₄-BaF₂ were obtained, and the glass forming ability of this system was evaluated. The effects of glass composition on both thermal stability and the crystalline phases formed upon heat treatment were determined by the DSC and XRD methods, respectively. The composition with higher thermal stability and better glass forming ability contained 2 mol% of oxides.     

Low‐Bandgap Cs4CuSb2Cl12 Layered Double Perovskite: Synthesis,Reversible Thermal Changes,and Magnetic Interaction

Double perovskites (DPs) with a generic formula A₂M′(I)M^IIIX₆ (A and M are metal ions, and X=Cl, Br, I) are now being explored as potential alternatives to Pb‐halide perovskites for solar cells and other optoelectronic applications. However, these DPs typically suffer from wide (≈3 eV) and/or indirect band gaps. In 2017, a new structural variety, namely layered halide DP Cs₄CuSb₂Cl₁₂ (CCSC) with bivalent Cu^II ion in the place of M′(I) was reported, which exhibit a band gap of approximately 1 eV. Here, we report a mechanochemical synthesis of CCSC, its thermal and chemical stability, and magnetic response of Cu^II d⁹ electrons controlling the optoelectronic properties. A simple grinding of precursor salts at ambient conditions provides a stable and scalable product. CCSC is stable in water/acetone solvent mixtures (≈30 % water) and many other polar solvents unlike Pb‐halide perovskites. It decomposes to Cs₃Sb₂Cl₉, Cs₂CuCl₄, and SbCl₃ at 210 °C, but the reaction can be reversed back to produce CCSC at lower temperatures and high humidity. A long‐range magnetic ordering is observed in CCSC even at room temperature. The role of such magnetic ordering in controlling the dispersion of the conduction band, and therefore, controlling the electronic and optoelectronic properties of CCSC has been discussed.     

苯甲酸钐的水热合成和热分解反应机理

用水热法合成了无水苯甲酸钐配合物,经元素分析、IR和X射线粉末衍射表征了该配合物,系层状结构,属单斜晶系。用TG、DTA、IR、色谱-质谱联用仪研究了它的热分解机理。在氮气氛下,热分解分两步进行:第一步分解生成钐的二碳酸一氧盐和有机化合物。生成的有机化合物成分比较复杂,主要成分为苯甲酸、二苯甲酮、9,10-蒽醌和1,3-二苯基异苯并呋喃等。第二步二碳酸一氧盐进一步分解生成氧化钐和二氧化碳。     

Nanosized cobalt-based catalyst prepared by supercritical phase condition for Fischer-Tropsch synthesis

A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis (FTS) were prepared by supercritical fluid drying (SCFD) method and common drying (CD) method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH₄ and CO₂ as well as higher yield of C₅₊ products were achieved. The optimal performance of a 92% CO conversion and a 65% C₅₊ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C₅₊ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO₂ byproduct, and higher yield of C₅₊ products.     

Characterization and thermal behavior of hydroxyapatite prepared by precipitation

Journal of Thermal Analysis and Calorimetry - The aim of this study was to find appropriate precipitation conditions (Ca/P ratio, pH and precipitation rate) for the synthesis of hydroxyapatite...     

（4，4＇-bipyH）3[PW12O40]（4，4＇-bipy）·7H2O的水热合成、晶体结构与热性质

用中温水热技术合成了(4,4'-bipyH)3[PW12O40](4,4'-bipy)·7H2O,用元素分析、X射线单晶衍射、IR、UV-vis和TG-DTA 对其进行了表征.结果表明,化合物的晶体属单斜晶系,P2(1)/c空间群.标题化合物是由3个质子化的4,4'-bipy分子、一个Keggin结构的钨磷杂多阴离子[PW12O40]3-和一个4,4'-bipy分子及7个结晶水分子所组成.钨磷杂多阴离子与质子化的联吡啶及结晶水分子之间通过氢键作用,连接成无限二维层状结构,形成超分子化合物.     

Thermodynamical modeling of silicon carbide synthesis in thermal plasma

The synthesis process of solid SiC in thermal plasma was investigated theoretically by computing the equilibrium composition of the gas mixtures involving silicon and carbon in the presence of argon and hydrogen at various silicon/carbon amounts and at two different total pressures in the system, in the temperature range between 1000 and 6000 K. Use is made of the fact that a thermal plasma, by definition, is a plasma in (local) thermodynamical equilibrium, which makes possible the theoretical determination of its equilibrium composition at definite temperature by employing Gibbs free energy data for the compounds present in the system. From the calculated compositions of the investigated gas systems the temperature-composition phase diagrams were obtained. Using these data the temperature zones with saturated and/or oversaturated vapour of SiC as well as of Si and C were determined and the possibility of the formation of SiC in the solid state via different reaction routes was analyzed This revised version was published online in July 2006 with corrections to the Cover Date.     

Rheological and thermal behavior of PLA modified by chemical crosslinking in the presence of ethoxylated bisphenol A dimethacrylates

Crosslinking structures can be partly introduced into PLA by melt mixing in a twin screw extruder with dicumyl peroxide (DCP) and ethoxylated bisphenol A dimethacrylates (Bis‐EMAs) as a crosslinking coagent. The study of DCP and Bis‐EMA contents on the melt rheology, thermal properties, dynamic mechanical properties and morphology of the reactive extruded pellets is presented. The results show that PLA with a DCP content higher than 3 phr exhibits increases in both the melt modulus and complex viscosity as compared with PLA. The introduction of DCP into PLA improved the thermal stability of the PLA. PLAs with various Bis‐EMA contents showed the optimum storage modulus and complex viscosity to occur at 5 phr Bis‐EMAs. Moreover, the glass transition, cold crystallization and melting temperature of PLAs decreased with increasing Bis‐EMA content. The crystallinity of the partly crosslinked PLAs was lower than that of PLA. Similar to the rheological results, the thermo‐mechanical properties showed that the storage modulus and loss modulus of the partly crosslinked PLAs increased with increasing Bis‐EMA contents up to 5 phr. In addition, these partly crosslinked PLAs showed rough surface or sea island‐like structure. Copyright © 2016 John Wiley & Sons, Ltd.     

在超临界正己烷介质中的F-T合成反应行为

在固定床反应器中,以正己烷为超临界介质,研究了三种Co催化剂（浸渍、喷雾干燥、双模催化剂）上的F-T合成反应行为。在相同的Co质量分数下,喷雾干燥催化剂和双模催化剂的活性接近,都高于浸渍催化剂。在喷雾干燥催化剂上CO的转化率显著高于浸渍催化剂。喷雾干燥催化剂F-T产物中具有高的低碳选择性和低的1-烯烃质量分数,然而在相近的CO转化率下,喷雾干燥和浸渍催化剂具有类似的1-烯烃质量分数。对于浸渍催化剂,当Co质量分数从5％增加到15％,CO转化率从8.3％增加到43.6％。含Co5％的催化剂比质量分数为10％、15％、20％催化剂的甲烷选择性低2.0%～3.0%,但产物中1-烯烃的质量分数明显要高。     

Unsaturated polyamides and polyesters prepared from 1,4-bis(2-carboxyvinyl)benzene and 4-hydroxycinnamic acid

Various unsaturated polyamides and polyesters were prepared from the reactions of 1,4-bis(2-carboxyvinyl)benzene acid chloride with aromatic diamines and bisphenols, respectively. In addition, various unsaturated homo- and copolyesters were synthesized from 4-hydroxycinnamic acid and 4-hydroxybenzoic acid. They were heat-cured to thermally stable resins. The polymers were characterized by inherent viscosity measurements, FT-IR, x-ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The water absorption as well as the solubility behavior of the polymers was also investigated. © 1996 John Wiley & Sons, Inc.     

奈达铂的新合成方法、晶体结构和热稳定性

本文报道了铂族金属抗癌药物奈达铂的一种新合成方法,产率约65%,精品含量超过99%。采用了元素分析、红外光谱、质谱、差热-热重分析和X射线衍射手段对其结构和组成进行了表征。该配合物的晶体属正交晶系,空间群P2₁2₁2₁。单晶X射线衍射结构分析结果表明铂(Ⅱ)离子与2个氨分子的氮原子以及乙醇酸羟基和羧基的氧原子配位,形成平面正方形结构,乙醇酸的二价阴离子通过羟基和羧基上的氧原子与铂(Ⅱ)离子配位形成五原子的螯合物。经TG-DTA