Home About us Contact
|
Home About us Contact | ||
|
|
||
Film-forming Properties (film-forming + property)
Selected AbstractsElectroluminescence and Laser Emission of Soluble Pure Red Fluorescent Molecular Glasses Based on DithienylbenzothiadiazoleADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Ju Huang Abstract Soluble molecular red emitters 1a/1b are synthesized by Stille coupling from 2-(3,5-di(1-naphthyl)phenyl)thiophene precursors. The compounds show emission maxima at ca. 610,nm in CH2Cl2 solution and 620,nm in solid films. Replacing the n -hexyl substituent by 4- sec -butoxyphenyl produces a marked increase of glass transition temperature (Tg) from 82,°C to 137,°C and increases the solubility in toluene and p -xylene, thus improving the film-forming properties. Cyclic voltammetry shows that the compounds can be reversibly oxidized and reduced around +1.10 and ,1.20,V, respectively. A two-layered electroluminescent device based on 1b produces a pure red light emission with CIE coordinates (0.646, 0.350) and a maximal luminous efficiency of 2.1,cd A,1. Furthermore, when used as a solution-processed red emitter in optically pumped laser devices, compound 1b successfully produces a lasing emission at ca. 650,nm. [source] V-Shaped Thiophene-Based Oligomers with Improved Electroluminescence Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2005G. Barbarella Abstract The synthesis via the Stille coupling of a new family of oligomers derived from benzo[b]thiophene is reported. Owing to their branched molecular structure lacking any symmetry element, these compounds display a low tendency to crystallization and better film-forming properties than their linear counterparts. Spin-coated films show photoluminescence efficiencies up to 50,%. Light-emitting diodes with spin-coated films as the active layers display markedly improved performance with respect to similar devices based on linear oligothiophenes, with luminance values up to more than 10,000,cd,m,2. Semiempirical PM3 and ZINDO/S calculations provide insight into the molecular geometries and electron distribution of the frontier orbitals of the new compounds. Cyclic voltammetry data indicates that the transformation of the thienyl sulfur of benzo[b]thiophene to the corresponding thienyl- S,S -dioxide leads an increase in electron affinity by 0.5,0.7,V, analogous to that of the corresponding linear oligomers. [source] Synthesis of Polyanilines Bearing Optically Active SubstituentsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2006Hiromasa Goto Abstract Summary: Optically active polyanilines were prepared by an interfacial polymerization with (NH4)2S2O8 in a water/perchloric acid/chloroform system. The pristine polymer obtained in this way is in the oxidized (doped) form. The polymers display the mirror-image Cotton effect. The doping process in solution allows a change in the circular dichroism of the polymer. The procedure has great potential in the improved preparation of durable optoelectrical devices based on the good film-forming properties of chiral polymers. CD spectra of R - P2 (solid line) and S - P2 (dashed line) in 4.0,×,10,4M THF solution. [source] Advancing the Solid State Properties of Metallo-Supramolecular Materials: Poly(, -caprolactone) Modified , -Conjugated Bis(terpyridine)s and their Zn(II) Based Metallo-PolymersMACROMOLECULAR RAPID COMMUNICATIONS, Issue 20 2008Andreas Winter Abstract A set of rigid , -conjugated bis(terpyridine) macroligands with poly(, -caprolactone) (pCL) on their side chains was synthesized and investigated. The introduced pCL chains gave rise to enhanced processability and film-forming properties of the materials. Blue photoluminescence with high quantum yields was observed in dilute solution and in the solid state, indicating that intermolecular aggregation of the , -conjugated systems was effectively suppressed. The macroligands were further used for coordination with zinc(II) ions leading to new metallo-polymers with high solubility, improved film-forming behavior and promising photophysical properties with respect to potential OLED applications. [source] Novel Polymer Electrolyte Membrane, Based on Pyridine Containing Poly(ether sulfone), for Application in High-Temperature Fuel CellsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 21 2005Elefterios K. Pefkianakis Abstract Summary: Novel poly(aryl ether sulfone) copolymers containing 2,5-biphenylpyridine and tetramethyl biphenyl moieties were synthesized by polycondensation of 4-fluorophenyl sulfone with 2,5-(4,,4, dihydroxy biphenyl)pyridine and tetramethyl biphenyl diol. Copolymers with different molecular weights and different monomer compositions were obtained. These copolymers exhibit excellent film-forming properties, mechanical integrity, and high modulus up to 250,°C, high glass transition temperatures (above 280,°C) as well as high thermal stability up to 400,°C. In addition to the above properties required for PEMFC application, this novel material shows high oxidative stability and acid doping ability, enabling proton conductivity in the range of 10,2 S,·,cm,1 above 130,°C. Synthesis of copolymers with high acid uptake and ionic conductivity. [source] Polymer electrolyte membranes for high-temperature fuel cells based on aromatic polyethers bearing pyridine unitsPOLYMER INTERNATIONAL, Issue 11 2009Joannis K Kallitsis Abstract This review is focused on the design and synthesis of new high-temperature polymer electrolytes based on aromatic polyethers bearing polar pyridine moieties in the main chain. Such materials are designed to be used in polymer electrolyte fuel cells operating at temperatures higher than 100 °C. New monomers and polymers have been synthesized and characterized within this field in respect of their suitability for this specific application. Copolymers with optimized structures in order to combine excellent film-forming properties with high mechanical, thermal and oxidative stability and controlled acid uptake have been synthesized which, after doping with phosphoric acid, result in ionically conducting membranes. Such materials have been studied in respect of their conductivity under various conditions and used for the construction of membrane-electrode assemblies (MEAs) which are used for fuel cells operating at temperatures up to 180 °C. New and improved, in terms of oxidative stability and mechanical properties in the doped state, polymeric membranes have been synthesized and used effectively for MEA construction and single-cell testing. Copyright © 2009 Society of Chemical Industry [source] Film-forming process and biocide assessment of high-molecular-weight chitosan as determined by combined ATR-FTIR spectroscopy and antimicrobial assaysBIOPOLYMERS, Issue 6 2006P. Fernandez-Saiz Abstract This pioneering study reported about the film-forming properties of high-molecular-weight chitosan as followed in situ by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and has implications in fields such as biomedical, pharmaceutical, packaging, and coating applications. From the results, it was observed that immediately after dissolution in an acetic acid aqueous solution and subsequent casting over the ATR crystal, the formed carboxylate antimicrobial (NH,OOCH) species are not stable in the film formulation and become reduced over time; further assays confirmed previous research, which suggested that the presence and stability of these groups is strongly dependent, among other factors, on storage conditions. As-received chitosan and chitosan neutralized in NaOH films did not exhibit biocide performance towards Staphylococcus aureus. The antimicrobial tests were also found to strongly relate the presence of a sufficient quantity of these carboxylate groups to the chitosan activity as a biocide agent. Moreover, a novel methodology based on the use of a normalized infrared band centered at 1405 cm,1 is proposed which can be correlated with the antimicrobial character of the biopolymer. © 2006 Wiley Periodicals, Inc. Biopolymers 83: 577,583, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Synthesis, Photophysics and Morphology of a Conjugated Polymer with Azobenzene Building Block in the BackboneCHINESE JOURNAL OF CHEMISTRY, Issue 7 2010Dezhi Shen Abstract A conjugate polymer poly[p -(phenyleneethylene)-alt-(phenyleneazophenyleneethylene)] (PPEPAPE) containing azobenzene building block in the polymer backbone was synthesized via Sonogashira cross-coupling of 4,4,-diiodoazobenzene and 1,4-diethynyl-2,5-didodecyloxybenzene. All the monomers and the resulting polymer were well characterized. The polymer had a relatively high molecular weight and showed very good solubility (,10 mg/mL) in common organic solvents. The photophysics of this polymer in solution and in film was investigated. The surface morphology of the films was studied by scanning electron microscope (SEM) and the relationship between the morphology and absorbance was discussed. This polymer has good film-forming property, broad absorbance and no emission, which might make it a good candidate for the photovoltaic material in the solar cell. [source] | |||||||||||||