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DMF Solution (dmf + solution)
Selected AbstractsSynthesis and characterization of novel poly(arylene ether)s based on 9,10-bis-(4-fluoro-3-trifluoromethylphenyl) anthracene and 2,7-bis-(4-fluoro-3-trifluoromethylphenyl) fluoreneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Arun K. Salunke Abstract Two new bisfluoro monomers 9,10-bis-(4-fluoro-3-trifluoromethylphenyl) anthracene and 2,7-bis-(4-fluoro-3-trifluoromethylphenyl) fluorene have been synthesized by the cross-coupling reaction of 2-fluoro-3-trifluoromethyl phenyl boronic acid with 9,10-dibromo anthracene and 2,7-dibromo fluorine, respectively. These two bisfluoro compounds were used to prepare several poly(arylene ether)s by aromatic nucleophilic displacement of fluorine with various bisphenols; such as bisphenol-A, bisphenol-6F, bishydroxy biphenyl, and 9,9-bis-(4-hydroxyphenyl)-fluorene. The products obtained by displacement of the fluorine atoms exhibits weight-average molar masses up to 1.5 ×105 g mol,1 and number average molecular weight up to 6.8 × 104 g mol,1 in GPC. These poly(arylene ether)s show very high thermal stability even up to 490°C for 5% weight loss occurring at this temperature in TGA in synthetic air and showed glass transition temperature observed up to 310°C. All the polymers are soluble in a wide range of organic solvents, e.g., CHCl3, THF, NMP, and DMF. Films cast from DMF solution are brittle in nature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] High quantum yield photoluminescence of new polyamides containing oligo-PPV amino derivatives and related oligomersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2009Antonio Roviello Abstract The synthesis and the chemical physical characterization of new photoluminescent (PL) chromophores and polymers are reported. Chromophores (oligo-PPV symmetric derivatives ending with amino groups) are strong blue emitters with a PL quantum yield of ,70% in dioxane solution. They have been used to prepare polyamides by reaction with aliphatic acyl dichlorides in which emitting and non emitting units are alternated. PL properties of the synthesized polyamides have been evaluated in solution and reveal a strong blue emission (PL quantum yield ,60%), To increase the solubility of these systems, oligomers have been purposely prepared and then characterized. They show a peculiar white emission when excited in DMF solution; to get insight into this interesting behavior, asymmetric monoacetylated chromophores have been prepared as model compounds for the chromophoric end groups of the polyamide chains. The emission spectra of these compounds reveal a broad excimeric yellow emission which is responsible, along with the blue emission of the inner chromophoric units, of the overall white emission of the oligomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2677,2689, 2009 [source] Synthesis of soluble branched polyimides derived from an ABB, monomerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2004Kun-Li Wang Abstract A novel ABB, monomer, an isomeric mixture of 4-[4-(2,4-diaminophenoxy)phenoxy]phthalic acid 2-methyl ester, was successfully prepared. The direct polycondensation of the ABB, monomer was carried out to form polyamic acid monomethyl ester as a precursor with an inherent viscosity of 0.30 dL/g and a number-average molecular weight of 12,000. The degree of branching of the precursor, determined by 1H NMR, was 0.07. The low degree of branching was caused by the differences in the reactivities of the amino groups. The shape factor was calculated to be 0.72. End-modified reactions with acetyl chloride, benzoyl chloride, and phthalic anhydride were carried out. After the chemical imidization of the end-modified precursors, end-modified polyimides were successfully prepared. The end-modified polyimides were soluble in dimethyl sulfoxide, dimethylformamide (DMF), and N -methyl-2-pyrrolidinone. On the basis of thermogravimetry and differential scanning calorimetry measurements of the polyimides, the 5 wt % thermal loss temperatures were determined to be 400,520 °C, and the glass-transition temperatures were determined to be 200,258 °C. According to the X-ray diffraction measurements, the end-modified polyimides were amorphous. A strong but brittle film was prepared from an acetamide end-modified polyimide solution, via casting from a DMF solution, with a tensile strength of 46 MPa, an elongation at break of 4%, and a modulus of 1.3 GPa. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3200,3211, 2004 [source] Synthesis, Crystal Structure of Co(II)(6-methoxybenzothiazole- 2-carboxylate)2(DMF)2 and Its Application to Carbonylation of Benzyl ChlorideCHINESE JOURNAL OF CHEMISTRY, Issue 1 2010Bin Zhang Abstract A new complex, Co(MBTC)2(DMF)2 (MBTC=6-methoxybenzothiazole-2-carboxylate, DMF=N,N -dime- thylformamide), was synthesized in DMF solution and characterized by single crystal X-ray diffraction analysis. Using the cobalt complex as catalyst, phenylacetic acid was prepared by the carbonylation of benzyl chloride with carbon monoxide (0.1 MPa). The effects of solvents, phase transfer catalysts and temperature on the reactions were investigated. The yield of phenylacetic acid was higher than 90% in optimized condition. [source] Michael-Addition Reaction of Malononitrile with ,,,-Unsaturated Cycloketones Catalyzed by KF/Al2O3CHINESE JOURNAL OF CHEMISTRY, Issue 2 2004Xiang-Shan Wang Abstract A series of KF/Al2O3 catalyzed Michael-addition reactions between malononitrile and ,,,-unsaturate cycloketones in DMF solution were studied. At room temperature, 2-cyano-3-aryl-3,(1, 2, 3, 4-tetrahydronaphthalen-1-one-2-yl) propionitrile derivatives were synthesized by the reaction between 2-arylmethylidene-1, 2, 3, 4-tetra-hydronaphthalen-l-one and malononitrile. However, if the temperature was increased to 80 C, 2-amino-3-cyano-4-aryl-4H -benzo[h]chromene derivatives were obtained in high yields. When the ,,,-unsaturated ketones were replaced by 2, 6-biarylmethylidenecyclohexanone or 25-biarylmethylidenecyclopentanone, another series of 2-amino-3-cyano-4H -pyran derivatives was isolated successfully. The structures of the products were confirmed by X-ray diffraction analysis. [source] Synthesis and Crystal Structure of the Copper Complex of 7,16-Bis(2-hydroxy-5-methylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecaneCHINESE JOURNAL OF CHEMISTRY, Issue 1 2004Shu-Lan Ma Abstract A lariat crown ether ligand 7.16-bis (2-hydroxy-5-methylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (Ll) has been prepared via one-pot Mannich reaction. Its copper(II) complex Cu-Ll was synthesized and characterized by elemental analysis, IR and UV-visible spectroscopy. The crystal structure of the complex has been determined by X-ray diffraction analysis. The result shows that the copper(II) ion is six-coordinated by two nitrogen and four oxygen atoms, two from the crown ether and the other two from the deprotonated phenolate anions, forming an elongated octahedral complex. Electrochemical study indicates that the complex undergoes reversible reduction in DMF solution. [source] Physically and Chemically Cross-Linked Poly{[(maleic anhydride)- alt -styrene]- co -(2-acrylamido-2-methyl-1-propanesulfonic acid)}/Poly(ethylene glycol) Proton-Exchange MembranesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2007lser G. Devrim Abstract Novel proton exchange membranes were solvent-cast from DMF solutions of the terpolymers poly[(MA- alt -S)- co -AMPS], containing hydrophobic phenyl and reactive hydrophilic carboxylic and organo-sulfonic acid fragments with different compositions, and PEGs with different molecular weights and amounts. These membranes were formed as a result of physical (via H-bonding) and chemical (via PEG) cross-linking. The structures of membranes were confirmed by FT-IR and 1H- and 13C NMR spectroscopy. Mechanical and thermal properties, swellability, and proton conductivity of these membranes were significantly affected both by the chemical composition of the terpolymers (mainly the AMPS content) and also the cross-linker (PEG) molecular weight and content in the final form of the membranes. It was concluded that the membranes prepared by using the terpolymer with an AMPS content of 36.84 mol-% and PEG with a molecular weight of 1,450 and with an initial PEG content of 30 wt.-% are the most suitable ones for fuel cell applications. [source] Multienzyme catalysis in microfluidic biochipsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003Moo-Yeal Lee Abstract The attachment of enzymes to glass microfluidic channels has been achieved using a highly reactive poly(maleic anhydride- alt -,-olefin) (PMA)-based coating that is supplied to the microchannel in a toluene solution. The PMA reacts with 3-aminopropyltriethoxysilane groups linked to the glass surface to form a matrix that enables additional maleic anhydride groups to react with free amino groups on enzymes to give a mixed covalent,noncovalent immobilization support. Using a simple T-channel microfluidic design, with reaction channel dimensions of 200 ,m wide (at the center), 15 ,m deep, and 30 mm long giving a reaction volume of 90 nL, soybean peroxidase (SBP) was attached at an amount up to 0.6 ,g/channel. SBP-catalyzed oxidation of p -cresol was performed in aqueous buffer (with 20% [v/v], dimethylformamide) containing H2O2, with microfluidic transport enabled by electroosmotic flow (EOF). Michaelis,Menten kinetics were obtained with Km and Vmax values of 0.98 mM and 0.21 ,mol H2O2 converted/mg SBP per minute, respectively. These values are nearly identical to nonimmobilized SBP kinetics in aqueous,DMF solutions in 20-,L volumes in 384-well plates and 5-mL reaction volumes in 20-mL scintillation vials. These results indicate that SBP displays intrinsically native activity even in the immobilized form at the microscale, and further attests to the mild immobilization conditions afforded by PMA. Bienzymic and trienzymic reactions were also performed in the microfluidic biochip. Specifically, a combined Candida antarctica lipase B,SBP bienzymic system was used to convert tolyl acetate into poly(p -cresol), and an invertase,glucose oxidase SBP trienzymic system was used to take sucrose and generate H2O2 for SBP-catalyzed synthesis of poly(p -cresol). © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 20,28, 2003. [source] | ||||||||||