Tribological performance and thermal behavior of epoxy resin nanocomposites containing polyurethane and organoclay

A series of epoxy resin nanocomposites modified by polyurethane and organically modified montmorillonite was prepared by effectively dispersing the organically modified montmorillonite in interpenetrating polymer networks (IPNs) of epoxy and polyurethane via the sequential polymeric technique and in situ polymerization. The tribological performance of the resultant EP/PU nanocomposites was investigated by a pin‐on‐disc tester, and the results showed that adding polyurethane and organically modified clay to the EP matrix had a synergistic effect on improving tribological performance of EP/PU nanocomposites. The morphologies of the worn surface were studied by scanning electron microscopy (SEM) observations, and the results indicated that the mechanism of improving tribological performance of EP/PU nanocomposites was different from that of pure EP or pure EP/PU IPNs. The thermal behavior of these nanocomposites was also investigated by thermogravimeric analysis (TGA), and the results indicated that adding organically modified clay to the matrix remedied the deterioration of the thermal degradation temperature of the interpenetrating networks. Copyright © 2008 John Wiley & Sons, Ltd.     

{Co6}簇加成的夹心型锗钨酸盐的合成、结构及电化学性质

通过水热反应合成了一个{Co₆}簇加成的夹心型锗钨酸盐：[Co(dien)₂]{[Co(dien)(H₂O)]₂[Co(dien)]2[Co₆(en)₂(μ₃-OH)₂(H₂O)₆(GeW₈O₃₁)₂]}·5.5H₂O (1),其中dien=diethylenetriamine,en=ethylenediamine。该化合物的阴离子是一个带状{Co₆}簇夹心的三明治型{Co₆}@{GeW₈}₂结构。通过单晶X射线衍射、元素分析、红外光谱、粉末X射线衍射和热重实验对该化合物进行了系统性地表征。通过循环伏安测试研究了该化合物的电化学性质,同时其在电催化还原亚硝酸盐实验中展现出良好的催化活性。     

{Co6}簇加成的夹心型锗钨酸盐的合成、结构及电化学性质

通过水热反应合成了一个{Co₆}簇加成的夹心型锗钨酸盐:[Co(dien)₂]{[Co(dien)(H₂O)]₂[Co(dien)]₂[Co₆(en)₂(μ₃-OH)₂(H₂O)₆(GeW₈O₃₁)₂]}·5.5H₂O (1), 其中 dien=diethylenetriamine, en=ethylenediamine。该化合物的阴离子是一个带状{Co₆}簇夹心的三明治型{Co₆}@{GeW₈}₂结构。通过单晶 X射线衍射、元素分析、红外光谱、粉末 X射线衍射和热重实验对该化合物进行了系统性地表征。通过循环伏安测试研究了该化合物的电化学性质, 同时其在电催化还原亚硝酸盐实验中展现出良好的催化活性。     

Two tris(oxalato)ferrate(III) hybrid salts with pyridinium derivative isomers as counter cations: synthesis,crystal structures,thermal analyses,and magnetic properties

Two organic–inorganic hybrid salts, tris(2-amino-4,6-dimethylpyridinium) tris(oxalato)ferrate(III), (C₇H₁₁N₂)₃[Fe(C₂O₄)₃] (1), and tris(4-dimethylaminopyridinium) tris(oxalato)ferrate(III) tetrahydrate, (C₇H₁₁N₂)₃[Fe(C₂O₄)₃]·4H₂O (2), have been synthesized and characterized by elemental and thermal analyses, IR spectroscopy, single-crystal X-ray diffraction, and SQUID magnetometry. Compounds 1 and 2 crystallize in triclinic P-1 and monoclinic C2/c space groups, respectively. Each compound contains the anionic complex [Fe(C₂O₄)₃]^3- in which the central metal is six-coordinate in a slightly distorted octahedron defined by three chelating oxalate(2-) ligands. The two substituted pyridinium cations are isomers. However, due to the great steric hindrance provided by the bulky cation, 2-amino-4,6-dimethylpyridinium, only the 4-dimethylaminopyridinium cation, the smallest of this series, led to formation of 2 with enough vacant spaces to be occupied by four solvent water molecules. In the crystals, cations and anions are connected via hydrogen-bonds of the types N–H?O in 1 and N–H?O and O–H?O in 2, with π–π stacking interactions between the pyridine rings stabilizing the 3-D framework. The thermal studies confirmed the anhydrous character of salt 1 and the presence of water molecules in salt 2. The magnetic susceptibility measurements in the 2–300 K temperature range revealed weak antiferromagnetic coupling in the two salts.     

Synthesis and properties of polyimide ionomers containing sulfoalkoxy and fluorenyl groups

A series of sulfopropylated and sulfobutylated polyimide copolymers containing fluorenyl groups, SPI‐4, were synthesized to investigate the effect of alkyl side chains on the properties (stability, mechanical strength, water uptake, and proton conductivity) of the polymimide electrolyte membranes. SPI‐4 showed much better hydrolytic stability (in 10% MeOH aq at 100 °C) than the main chain sulfonated polyimide, SPI‐1. Tough, flexible, and ductile membranes were obtained from these copolymers. At high relative humidity all the SPI‐4 membranes showed high mechanical properties (>34 MPa of the maximum stress) and proton conductivity (>0.1 Scm^?1). These properties are comparable to or even better than those of the perfluorosulfonic acid ionomer (Nafion 112). The new polyimide ionomers have proved to be a possible candidate as polymer electrolyte membrane for PEFCs and DMFCs. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4439–4445, 2005     

Synthesis,characterization, and thermal properties of silicon(IV) compounds containing amidinate ligands as CVD precursors

The title compounds of the type R-C(=NⁱPr) (-N′ ⁱPrSiMe₃) (with R = Me or ⁿBu) as potential chemical vapor deposition (CVD) precursors have been synthesized and characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy as well as by EI-MS and elemental analysis where necessary. Thermal properties, including stability, volatility, transport behavior, and vapor pressure, were evaluated by thermogravimetric analysis to confirm that they are suitable for the CVD procedure. Deposition was accomplished in a hot wall CVD reactor system, which qualitatively verified the ability of these compounds as CVD precursors.     

A novel benzimidazole moiety‐containing benzoxazine: Synthesis,polymerization, and thermal properties

A novel benzoxazine‐containing benzimidazole moiety (P‐PABZ) was synthesized from 2‐(4‐aminophenyl)‐1H‐benzimidazole‐5‐amine and characterized. With the aid of differential scanning calorimetry and in situ Fourier transform infrared, we found the thermal polymerization of P‐PABZ in bulk started around 140 °C and its favored polymerization pathway. Compared to the benzoxazine derived from 4,4′‐diamine diphenyl methane (P‐MDA), P‐PABZ exhibited lower processing temperature, and the corresponding polymers had higher glass transition temperature and enhanced thermal stability. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Precision ADMET polyolefins containing dithiane: Synthesis,thermal properties,and macromolecular transformation

1,3‐Dithiane and its derivatives are widely used as powerful acyl anion equivalent to a range of useful transformations that are needed in the synthesis of natural products. In this work, a series of polyolefins containing pendant dithiane groups have been designed and synthesized via acyclic diene metathesis polymerization (ADMET) polymerization and subsequent hydrogenation. The structures of these polymers were characterized by ¹H NMR, ¹³C NMR, and FT‐IR, and successful incorporation of the dithiane groups was proved. With different contents of the dithiane moieties, these ADMET polymers exhibited distinct thermal properties different from each other as evidenced by differential scanning calorimetry and thermal gravimetric analysis. The dithiane units in the ADMET polymer with 20 methylene carbons between the adjacent dithiane groups were transformed into thiol groups via reaction with Bu₃SnH. This work provided a convenient route to synthesize polyethylene with pendant thiol groups that are evenly distributed in the chain. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2468–2475     

Synthesis and properties of novel sulfonated polyimides containing 1,5‐naphthylene moieties

A series of novel sulfonated polyimides (equivalent weight per sulfonic acid = 310–744 g/equiv) containing 10–70 mol % 1,5‐naphthylene moieties were synthesized as potential electrolyte materials for high‐temperature polymer electrolyte fuel cells. The polycondensation of 1,4,5,8‐naphthalene tetracarboxylic dianhydride, 4,4′‐diamino‐2,2′‐biphenyldisulfonic acid, and 1,5‐diaminonaphthalene gave the title polymer electrolytes. The polyimide electrolytes were high‐molecular‐weight (number‐average molecular weight = 36.0–350.7 × 10³ and weight‐average molecular weight = 70.4–598.5 × 10³) and formed flexible and tough films. The thermal properties (decomposition temperature > 260 °C, no glass‐transition temperature), stability to oxidation, and water absorption were analyzed and compared with those of perfluorosulfonic acid polymers. The polyimide containing 20 mol % 1,5‐naphthylene moieties showed higher proton conductivity (0.3 S cm^?1) at 120 °C and 100% relative humidity than perfluorosulfonic acid polymers. The temperature and humidity dependence of the proton conductivity was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3901–3907, 2003     

Synthesis, curing behavior and thermal properties of fluorene containing benzoxazines

A series of difunctional fluorene-based benzoxazine monomers were synthesized from the reaction of 9,9-bis-(4-hydroxyphenyl)-fluorene with formaldehyde and primary amines including aniline, o-toluidine, n-butylamine, and n-octylamine. Their chemical structures were confirmed by FT-IR, ¹H and ¹³C NMR analyses. The curing behaviors of the precursors were monitored by differential scanning calorimetry (DSC) and FT-IR. The thermal properties of cured polymers were evaluated with DSC and thermogravimetric analysis (TGA). The fluorene-based polybenzoxazines show the typical curing characteristic of oxazine ring-opening for difunctional benzoxazines centred at 231-250 °C, and remarkably higher glass transition temperature and better thermal stability ascribed to the high rigidity, high aromatic content, and intermolecular and intramolecular hydrogen bonding. The thermal decomposition temperature and char yield of aromatic amine-fluorene-based polybenzoxazines are much higher than those of aliphatic amine-based polybenzoxazines.     

RAFT synthesis,properties and morphologies via thermal annealing of new azo-based ABA triblock copolymers bearing rigid and soft segments

In this study, a series of novel ABA-type triblock azo-copolymers (TBCs) consisting of PEG and PCAEMA segments were synthesized by RAFT polymerization. The TBCs were characterized by ¹H-NMR, GPC, DSC, OPM, AFM, GISAXS, and UV-vis. Number-average molecular weight (≤34,200?g/mol) and molecular weight distribution (≤1.44) were slightly increased with increasing the feed molar ratio of monomer to macroinitiator. This indicates a controlled/living polymerization with good distribution. All TBCs displayed transitions attributed to smectic-to-nematic and nematic-to-smectic phases at 108?°C and 104?°C, respectively. TBC with 34?wt% azobenzene displayed fan-shaped focal conic texture, while TBCs containing 46, 53, 58, 63, and 71?wt% azobenzene revealed batonnet textures. TBC-3 and TBC-4 having 53 and 58?wt% azo contents produced lamellar and a mixture of cylinder and lamellar nanostructures compared to other TBCs, which formed hexagonal cylindrical nanostructures. Every TBCs exhibited photoresponsive behavior under UV irradiation and thermal relaxation.     

Incorporation of Cadmium Ions and Cadmium Sulfide Particles into Sol-gel Zirconium Phosphate. Synthesis,thermal behavior and X-ray characterization

The inorganic ion-exchanger α-zirconium phosphate was synthesized by the sol-gel method and its properties relating to the exchange of Cd²⁺ and the intercalation of CdS particles were studied. The Cd²⁺-exchange process is a fast process and the material obtained exhibits an increased interlayer distance d with respect to its precursor (9.56 vs. 7.56 Å). The resulting Cd-containing material was exposed to aH₂S gas flow to give CdS particles in the exchanger. The zirconium phosphate containing CdS particles still possesses a layered structure, with a pattern almost identical to that of the initial ion-exchanger precursor. Moreover, the material may exchange further Cd²⁺ and hence lead to a higher CdS particle content. The thermal behavior of this ion-exchangers containing Cd²⁺ or CdS particles was studied.     

Oximato-bridged copper(II) compounds: syntheses,molecular structures,magnetic, thermal and spectroscopic properties

Reaction of the Schiff base, 1-(4-methylimidazol-5-yl) phenylhydrazonopropane-2-one oxime (LH), with copper(II) perchlorate hexahydrate and copper(II) nitrate trihydrate in a 1 : 1 M proportion in methanol affords [Cu₂L₂(H₂O)(ClO₄)](ClO₄) (1) and [Cu₂L₂(H₂O)₂](NO₃)₂] (2) in moderate yields. Both 1 and 2 have been characterized by elemental analysis, ESI-MS, FT-IR, UV–vis absorption spectroscopy, EPR, electric conductivity, and magnetic susceptibility measurements. The X-ray crystal structures of 1·CH₃COCH₃ and 2 have been determined. Both compounds are dinuclear copper(II) complexes, with each copper μ₂-bridged by two oxime ligands in a μ₂-η¹,η² fashion. Variable temperature magnetic studies on 1 and 2 show that both compounds are dominated by an antiferromagnetic coupling through the oxime bridges.     

基于[P_2W_(15)O_(56)]~(12-)构筑块的四核铜夹心型化合物的合成、结构表征及其热稳定性

以三缺位型Dawson结构的钨磷酸盐前驱体Na12[α-P2W15O56]·24H2O与CuCl2·6H2O和Na3PO4为原料、水为溶剂,经溶液合成法合成了四核夹心型多金属氧酸盐化合物Na3H13[Cu4(H2O)2(P2W15O56)2]·72H2O(1);利用X射线单晶衍射仪、红外光谱仪、紫外光谱仪、X射线粉末衍射仪等分析了合成产物的结构,采用变温红外光谱测定了其热性质.结果表明,该化合物为三斜晶系,P-1空间群;其晶胞参数为:a=1.318 1(2)nm,b=1.345 1(2)nm,c=2.497 3(4)nm,α=78.149(3)°,β=88.242(3)°,γ=62.087(2)°.该化合物的骨架结构由两个三缺位的Dawson结构单元{P2W15O56}通过一个{Cu4O16}簇连接而成;其在350℃以下表现出一定的热稳定性.     

Thermal decomposition of mixed Ce and Gd oxalates and thermal properties of mixed Ce and Gd oxides

The aim of the present work is to study the thermal decomposition of the mixed oxalates (Ce_1–xGd_x)₂(C₂O₄)₃·nH₂O. The mechanisms of decomposition of Ce and Gd oxalate are different, and mixed oxalates behave in an intermediate way. Their dehydration stages are more similar to those of Gd oxalate, as not all the molecules of water are equivalent like the cerium oxalate. The decomposition leads to (Ce_1–xGd_x)O_2–x/2. For x close to 0 or to 1 two solid solutions exist, while for the central composition, the presence of a biphasic region can not be excluded.     

Synthesis,thermal and optical properties of nanosized polyamides containing N-phenyl- and N-naphthyl-s-triazine rings: Structure-properties correlation

We prepared two series of nanosized polymers containing s-triazine moiety by reactions of newly prepared substituted diacids chlorides derived from 2-anilino-4,6-di-(phenoxy)- and 2-(N-1-naphthylamine)-4,6-di-(phenoxy)-s-triazines with a number of commercial diamines. The polymers were carefully characterized by different techniques including infrared, ultraviolet, fluorescent emission, elemental and thermal analyses and scanning electron microscopy (SEM). The SEM images indicated that most of the polyamides were organized as well defined nano sized spheres, but in certain derivatives small amount of aggregated nanospheres was also observed. Structure-property correlations based on a single or more interchange proved to be feasible. The polymers exhibited high thermal behavior and, based on the produced char yields, the limiting oxygen index (LOI) indicated that a dozen polymers were classified as “slow burning polymers” while the other dozen polymers were “self-extinguishing polymers.” Polymers derived from symmetric diamine exhibited better thermal stability than those containing asymmetric diamines. Interestingly, while the naphthyl/phenyl interchange has no influence on the thermal properties in some cases, however, dramatic improvements were noticed in many other cases. Obviously, the pyridine/phenylene interchange has no influence on the thermal properties of the addressed polymers. The polymers exhibited emissions ranging from blue to orange wavelength depending on the nature of the signaling unit. While the introduction of a naphthyl moiety has no significant influence on the electronic properties in some cases, however, the interchange led to either appreciable red-shifted absorptions or disrupt the conjugation and thus blue-shifted absorptions in other analogues. This result enables such polymers as good candidates in different technological applications.     

Novel mixed ligand coordination compounds of some rare earth metal cations containing acesulfamato/N,N-diethylnicotinamide

The mixed ligand coordination compounds containing acesulfamato and N,N -diethylnicotinamide biomolecules of some rare earth metal cations (Eu³⁺, Tb³⁺, Ho³⁺, Er³⁺ and Yb³⁺) were synthesized, and their structural properties were investigated. Possible structural formulas have been proposed by determining the chemical composition of molecules (elemental analysis), binding properties (infrared spectroscopy, mass analysis, solid-state UV-vis spectroscopy), thermal degradation properties (TGA / DTA curves). Based on the data collected, it is suggested that rare earth metal cations with a 3+ oxidation state have sextet coordination. The geometries of the structures were thought to be distorted octahedral. The charge balance of the coordination sphere is balanced by a monoanionic acesulfamato located outside the coordination sphere. When the thermal behaviours of the complexes were examined, it was determined that the compounds with Eu³⁺, Tb³⁺, and Yb³⁺ metal cations contained one hydrate water outside the coordination sphere. Hydrate waters do not exist in the Ho³⁺ and Er³⁺ metal cation-centred complexes. At the end of the thermal decomposition analysis of all complex structures, it was determined that they leave the relevant metal oxides in the reaction vessels as final decomposition products.     

One new lanthanide complex with mixed sulfate and oxalate ligands: hydrothermal synthesis,crystal structure,and magnetic properties

A new lanthanide complex K[Gd(ox)(SO₄)(H₂O)] (1) with sulfate and oxalate ligands has been synthesized under hydrothermal conditions. The compound crystallizes in the monoclinic space group P₂₁/c with a = 6.5849(1) Å, b = 8.5660(1) Å, c = 14.7660(2) Å, β = 112.470(1)°, C₂H₂GdKO₉S, M = 398.46, Z = 4, V = 769.66(2) ų, F(000) = 740, R ₁ = 0.0199 and ωR = 0.0514. The solid-state DC magnetic susceptibility measurements of 1 revealed antiferromagnetic behavior with an S = 7/2 ground spin state.