Synthesis and characterization nanocomposite of the graphene oxide/polyacrylic acid modified with 2-mercaptoethanol

In this research, synthesis and characterization of the nano-graphene oxide (GO) based on the modified polyacrylic acid (PAA) have been carried out. Formation of esteric bonds between the carboxyl functional groups of the GO surface and the hydroxyl groups of PAA was confirmed by FTIR spectroscopy. The result of this synthesis is covalent modification of graphene oxide during the polymerization process and this modification has caused improvement and change in some properties of graphene oxide including solubility of nanocomposite. Additionally, structure and stability of composite were studied by SEM, XRD and TGA.     

Synthesis and characterization of palladium amido complexes containing pincer CNO ligands through nitrene insertion

Catellani reactions of aryl iodides allow the double functionalization at the ortho and ipso positions in one pot. Catellani reactions involving a nitrene intermediate are not yet known. In this paper, a few palladium amino complexes were prepared from PdCl₂, anthranil and iodoarenes, and their structures were determined by X‐ray single‐crystal diffraction. These complexes are supported by a pincer C,N,O tridentate ligand forming fused six‐membered palladacycles. The high stability of the palladium complexes inhibits their reductive elimination.     

Pervaporation with chitosan membranes II. Blend membranes of chitosan and polyacrylic acid and comparison of homogeneous and composite membrane based on polyelectrolyte complexes of chitosan and polyacrylic acid for the separation of ethanol-water mixtures

Three different types of blend membranes based on chitosan and polyacrylic acid were prepared from homogeneous polymer solution and their performance on the pervaporation separation of water-ethanol mixtures was investigated. It was found that all membranes are highly water-selective. The temperature dependence of membrane permselectivity for the feed solutions of higher water content (>30 wt%) was unusual in that both permeability and separation factor increased with increase in temperature. This phenomenon might be explained from the aspect of activation energy and suggested that the sorption contribution to activation energy of permeation should not always be ignored when strong interaction occurs in the pervaporation membrane system.A comparison of pervaporation performance between composite and homogeneous membranes was also studied. Typical pervaporation results at 30°C for a 95 wt% ethanol aqueous solution were: for the homogeneous membrane, permeation flux = 33 g/m² h, separation factor = 2216; and for the composite membrane, permeation flux = 132 g/m² h, separation factor = 1008. A transport model consisting of dense layer and porous substrate in series was developed to describe the effect of porous substrate on pervaporation performance.     

Synthesis and characterization of square-planar palladium(II) complexes containing anti- and syn-furan-2-aldoxime

Summary Fifteen palladium(II) square-planar complexes containing monodentate and/or bidentate anti- and syn-furan-2-aldoxime (FDH) have been isolated and characterized by elemental analysis, molecular weight determination, conductance studies, magnetic moments and i.r. spectral studies. The monodentate ligand coordinates through the nitrogen atom while the bidentate ligand coordinates through the furan oxygen atom and the nitrogen atom. The C-O-C stretching frequency of the furan ring may be taken as the criterion for the denticity of this ligand and is observed at 1240 and 1270 cm^– in anti- and syn-furan-2-aldoxime respectively. A shift to lower frequency occurs (in the complex) if the ligand is bidentate, however this frequency is unaffected if the ligand is monodentate.     

Synthesis,characterization, and thermal behavior of palladium(II) complexes containing 4-iodopyrazole

The mononuclear pyrazolyl complexes [PdCl₂(HIPz)₂] (1), [PdBr₂(HIPz)₂] (2), [PdI₂(HIPz)₂] (3), [Pd(SCN)₂(HIPz)₂] (4), and [Pd(NHCOIPz)₂] (5) have been prepared. Compound 1 was obtained from the displacement of acetonitrile from [PdCl₂(CH₃CN)₂] precursor by the 4-iodopyrazole (HIPz) ligand, whereas 2–5 were synthesized by substitution of the chlorido in 1 by the respective anionic group. The compounds were characterized by elemental analysis, infrared spectroscopy, and ¹H NMR spectroscopy. The thermal behavior of 1–5 has been studied by TG and DTA. The thermal stability of [PdX₂(HIPz)₂] compounds varies according to the trends X = Cl^? < I^? ? SCN^?< Br^?. No stable intermediates were isolated during the thermal decompositions due to the overlap of the degradation processes. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction.     

Synthesis,characterization, and thermal behavior of palladium(II) coordination compounds containing isonicotinamide

Palladium(II) coordination compounds of general formula trans-[PdX₂(isn)₂], X = Cl⁻ (1), N₃ ⁻ (2), SCN⁻ (3), NCO⁻ (4), isn = isonicotinamide; were synthesized and characterized in solid state by elemental analysis, infrared spectroscopy, and simultaneous TG–DTA. TG experiments reveal that the compounds 1–4 undergo thermal decomposition in three or four stages, yielding Pd⁰ as final residue, according to calculus and identification by X-ray powder diffraction.     

Synthesis and characterization of piperazine containing polyaspartimides blended polysulfone membranes for fuel cell applications

Journal of Solid State Electrochemistry - A new polyaspartimide was synthesized via a Michael addition reaction of an aromatic bismaleimide (BMI) with aminoethylpiperazine (AEP) at 1:1 molar ratio....     

Electrophoretic deposition of polyacrylic acid and composite films containing nanotubes and oxide particles

Electrophoretic deposition (EPD) method has been developed for the deposition of thin films of polyacrylic acid (PAA). This method allowed the formation of uniform films of controlled thickness on conductive substrates. It was shown that PAA can be used as a common dispersing agent suitable for charging and EPD of various materials, such as multiwalled carbon nanotubes, halloysite nanotubes, MnO(2), NiO, TiO(2) and SiO(2). The feasibility of EPD of composite films containing the nanotubes and oxide particles in a PAA matrix has been demonstrated. The kinetics of deposition and deposition mechanisms were investigated and discussed. The films were studied by thermogravimetric analysis, differential thermal analysis, X-ray diffraction and scanning electron microscopy. The results indicated that film thickness and composition can be varied. Obtained results pave the way for the fabrication of PAA and composite films for biomedical, electrochemical and other applications.     

Synthesis monolithic copper-based aerogel with polyacrylic acid as template

Copper-based monolithic aerogel was prepared by sol?Cgel method with inorganic salt as precursor, the polyacrylic acid as template and the propylene oxide as gelation agent. The as-prepared aerogel was calcined at 400?°C to remove the organic substances and obtain crystalline copper-oxide nanostructured materials (tenorite, JCPDS File No. 00-045-0937). The aerogels?? structural properties were characterized by the field emission scanning electron microscopy, the high resolution transmission electron microscopy, the X-ray diffraction (XRD), and the Brunauer-Emmett-Teller methods. The results indicate that the as-prepared copper-based aerogel shows a typical three-dimensional porous structure with a large surface areas about 587?m²/g. The XRD patterns show that the as-prepared copper-based aerogel belongs to amorphous materials. The phase transition from the amorphous to crystalline copper oxide occurs at 400?°C.     

Synthesis, characterization and catalytic activity of three palladium(II) complexes containing Schiff base ligands

Three new Pd(II) complexes of Schiff base ligands, namely, [Pd₄(L¹)₄] (1), [Pd₂(L²)₂Cl₂] (2) and [Pd(L³)₂Cl₂] (3) [HL ¹ ?=?N-(benzylidene)-2-aminophenol; L ² ?=?N-(2,4-dichlorobenzylidene)-2,6-diethylbenzenamine, L ³ ?=?4-(2,4-dichlorobenzylide-neamino)phenol] have been synthesized using solvothermal methods and characterized by elemental analysis, spectroscopy and single crystal X-ray diffraction. The crystal structures of the free ligands were also determined. The ??-oxygen-bridged tetranuclear cyclometallated Pd(II) complex (1) contains four nearly planar units, in which Pd^II is four-coordinate. Complex 2 is a ??-chloro-bridged dinuclear cyclometallated Pd(II) complex, whereas complex 3 is mononuclear. The Heck reactions of bromobenzene with acrylic acid catalyzed by complexes 1?C3 have also been studied.     

超声波辅助合成低分子量聚丙烯酸钠

以过硫酸铵为引发剂,在超声波辅助下引发丙烯酸单体聚合。研究了单体浓度、引发剂用量、反应温度等对单体转化率和聚丙烯酸钠分子量的影响。结果表明:在超声作用下,能够加快聚合反应速度,提高转化率,但对产物聚合度影响很小;控制单体浓度30-40%、引发剂用量1.0%、反应温度50-70℃,在超声波作用下,制得聚丙烯酸钠的相对分子量在2,000-5,000之间。     

Synthesis and characterization of platinum and palladium pyrrolidinedithiocarbamate complexes

Treatment of (PPh₃)₂MCl₂ (M = Pd or Pt) with ammonium pyrrolidinedithiocarbamate (NH₄S₂CNC₄H₈) in a 1:1 molar ratio gave (PPh₃)M(Cl)(κ ² S,S-S₂CNC₄H₈) [M = Pt (1), Pd (2)]. On the other hand, the interaction of these compounds in a 1:2 [M:L] molar ratio gave (PPh₃)Pt(κS-S₂CNC₄H₈)(κ ² S,S-S₂CNC₄H₈) (3), which contains both terminal and chelated dithiocarbamato ligands, or a yellow insoluble solid for M = Pd. The bis(diphenylphosphino)ethane platinum or palladium dichlorides [(dppe)MCl₂] reacted with the same ligand to give the salts [(dppe)M(κ ² S,S-S₂CNC₄H₈)]Cl (M = Pt (4), Pd (5) which have only one chelating dithiocarbamato ligand. The new compounds were characterized by ¹H-, ¹³C{¹H}- and ³¹P-n.m.r. spectroscopy, mass spectrometry, elemental analysis and X-ray single crystal structure analysis.     

Synthesis of composite solid electrolytes based on polyacrylic acid via radical polymerization initiated from silica surface

A procedure has been developed for the synthesis of silica-supported polymerization initiators, which includes chemisorption of (3-aminopropyl)triethoxysilane, hydrolysis of the alkoxy groups, and chemisorption of 4,4′-azobis(4-cyanopentanoic acid). It has been found that the reaction of 4,4′-azobis(4-cyanopentanoic acid) with immobilized amino groups in the presence of N,N′-dicyclohexylcarbodiimide involves only one functional group in the former. The effect of the solid support porosity on the composition of organosilica obtained by surface-initiated radical polymerization of acrylic acid has been studied. The best yield of grafted polyacrylic acid is obtained on aerosilogel with large mesopores in combinations with developed surface. The dependence of the impedance of polyacrylic acid-modified aerosilogel on the relative air humidity has been studied, and the possibility of using this material in humidity sensors has been shown.     

Synthesis of doubly labeled polyacrylic acid with14C and3H

Polyacrylic hydrogels were¹⁴C- and³H-labeled in three main steps. In the first one, the monomer as sodium salt was¹⁴C-labeled at the carboxyl group via the carbonation of vinylmagnesium bromide and [1-¹⁴C]acrylic acid was obtained, followed by labeling with tritium via isotopic exchange in heterogeneous catalysis. The monomer was purified and its radiochemical purity was analyzed using TLC. In the last step, the hydrogel was obtained through radiopolymerization of the doubly labeled monomer using a⁶⁰Co source. The oligomers and unpolymerized monomers were eliminated from the hydrogel by swelling in water followed by dehydration with methanol.     

Synthesis and characterization of an epoxy based thermoset containing a fluorinated thermoplastic

A novel fluorinated thermoplastic (FT) was synthesized from diglycidyl ether of bisphenol A (DGEBA), and 3‐(trifluoromethyl)aniline. FT was found to be miscible with DGEBA as shown by the existence of a single glass transition temperature (T_g) within the whole composition range. On the basis of several experimental techniques, it was found that upon heating etherification reaction takes place between FT and DGEBA. A DGEBA‐aromatic diamine (4,4′‐methylenebis(3‐chloro 2,6‐diethylaniline) formulation was modified with the FT. The influence of FT on the epoxy‐amine kinetics was investigated. Both structural parameters, gelation, and vitrification, were found to be affected by etherification reaction between epoxy and hydroxyls groups belonging to FT. The presence of ether linkages induced system stoichiometry modification. In addition, the curing conditions influence on FT migration towards the surface was studied on samples prepared with 20 wt % of modifier. SEM–EDX analysis confirmed that modified systems exhibits notable fluorine enrichment within the uppermost 200 μm. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2781–2792, 2007     

Synthesis and characterization of biodegradable palm palmitic acid based bioplastic

This study involves the quantitative analysis of high free fatty acid crude palm oil, the separation of palmitic acid and synthesis of palm palmitic acid-based bioplastic. Synthesis of dimethyl 2-tetradecylmalonate (DMTDM) using methyl palmitate (MP) with sodium hydride (NaH) in the presence of reactive solvent of dimethyl carbonate (DMC) was carried out. The reaction conditions comprise at a mole ratio of MP: DMC: NaH: dimethylformamide (DMF) (0.1:2:0.25:1) at 60 °C for 14 h with 88.3 ± 1.4% yield. FTIR spectra of DMTDM showed the ester carbonyl group at 1740 cm^–1. The polymerization of DMTDM with 1,6-hexandiol or 1,12-dodecandiol was carried out using titanium (IV) isopropoxide Ti(OiPr)₄ as the catalyst and reaction time of 24 h. The results showed that the poly(dodecyl 2-tetradecylmalonte) (PDTDM) exhibited good thermal properties compared to poly(hexyl 2-tetradecylmalonte) (PHTDM). The increase of the chain length of diol in PDTDM improved the thermal properties of polyester with glass transition, T_g of 13 ºC and melting point of 51 ºC with a molecular weight of 12508 Da and polydispersity index (PDI) of 1.4. In general, the synthetic polyesters can be used as internalplasticizer in bio-based industry.     

Synthesis and characterization of fluorine‐containing polybenzimidazole for proton conducting membranes in fuel cells

Two new kinds of fluorine‐containing polybenzimidazoles (PBI), poly(2,2′‐(tetrafluoro‐p‐phenylene)‐5,5′‐bibenzimidazole) and poly(2,2′‐tetradecafluoroheptylene‐5,5′‐bibenzimidazole), were synthesized by condensation polymerization of 3,3′‐diaminobenzidine and perfluoroterephthalic acid (or perfluoroazelaic acid), with polyphosphoric acid as solvent. Thermogravimetric analysis results show that the fluorine‐containing polymers synthesized exhibit promising thermal stability. The film‐forming properties of the fluorine‐containing polymers are improved over nonfluorinated PBI. The introduction of fluorine into the backbone of the polymers has significant positive affection on their chemical oxidation stability demonstrated by Fenton test. Compared with poly(2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole)/phosphoric acid (PA) composite membrane, the resulting fluorinated membranes with a same PA doping level exhibit better flexibility and higher proton conductivity. The maximum proton conductivity gained is 3.05 × 10^?2 S/cm at 150 °C with a PA doping level of 7. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2115–2122, 2010     

Synthesis and structural characterization of a cocrystal salt containing acriflavine and 3,5-dinitrobenzoic acid

An acriflavine cocrystal salt with 3,5-dinitrobenzoic acid (stoichiometry 1:3) was synthesized and structurally characterized. This is the first crystal structure containing the acriflavine moiety to be documented and also the first in which a trimer of an aromatic monocarboxylic acid has been identified. In the crystal packing the trimers of 3,5-dinitrobenzoic acid form a porous organic framework, in the voids of which are located π-stacked columns of acriflavine cations.