Browsing by Author "Diaz, FR"

Now showing 1 - 6 of 6
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    Evaporated thin films of insulating poly-(tetrabromo-p-phenylenediselenide)
    (PERGAMON-ELSEVIER SCIENCE LTD, 2002) D'Almeida, K; Bernede, JC; Godoy, A; Diaz, FR; Mevellec, JY; Molinie, P
    It has been shown that thin insulating film at the interface transparent conductive oxide/organic electroluminescent film could improve the performance of organic electroluminescent diodes (OLED). Such insulating film can be inorganic or organic. Poly-(tetrabromo-p-phenylenediselenide) (FBrPDSe) has been proved to be an efficient insulating film in OLED. The properties of these evaporated PBrPDSe thin films have been systematically studied by IR absorption, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, electron spin resonance and optical transmission measurements. It is shown that, when the deposition temperature is kept below the decomposition temperature of the polymer, tetrabromo-p-phenylenediselenide molecule is preserved during the deposition process. However the polymer, which is insoluble in powder form, becomes soluble after deposition. It can be concluded that films are mainly composed of oligomers of tetrabromo-p-phenylenediselenide.
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    Smectic Cu(II), Pd(II) and VO(IV) complexes: Synthesis, EPR and thermogravimetric studies
    (TAYLOR & FRANCIS LTD, 1998) Diaz, FR; Valdebenito, N; Serrano, JL; Marcos, M; Martinez, JI; Alonso, PJ
    The octadecanoate of N-(4-hexyloxyphenyl)salicylaldimine and the corresponding Cu(II), Pd(II) and VO(IV) complexes were synthesized and studied. The compounds were characterized by IR, H-1 NMR, elemental and thermal analysis and polarized light microscopy. Thermogravimetric analysis and electronic spectra of the complexes are reported. Electron paramagnetic resonance (EPR) measurements were performed.
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    Synthesis and characterization of polyarylureas. I. Potentially semiconducting polymers
    (WILEY-BLACKWELL, 2001) Diaz, FR; Godoy, A; Moreno, J; Bernede, JC; Sanchez, CO; Opazo, A; Gargallo, L
    Polyarylureas were synthesized from the reaction between phosgene with aromatic diamines. Depending on the pH, the polyarylureas presented different colors when the solvent used was pyridine. The polyarylureas were characterized by IR spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy (XPS). To study the thermal stability of the polymers, a thermal degradation was performed between 35 and 700 degreesC. The polyarylureas decomposed above 350 degreesC. Without doping, polyarylureas are considered as semiconductors [sigma = 10(-9) (Omega cm)(-) (1)]; after doping with I-2, their electrical conductivity increases by several orders of magnitude. (C) 2001 John Wiley & Sons, Inc.
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    Thermal studies of poly(esters) containing silicon or germanium
    (SOCIEDAD CHILENA DE QUIMICA, 2001) Tagle, LH; Diaz, FR; Opazo, A
    The thermal properties of poly(esters) containing silicon or germanium in the main chain and derived from the diphenols bis(4-hydroxyphenyl)-diphenylsilane and bis(4-hydroxyphenyl)-diphenylgermane and isophthaloyl or terephthaloyl acid dichlorides were studied by differential scanning calorimetry and dynamic thermogravimetry. Poly(esters) derived from terephthalic acid showed higher Tg and thermal stability values than those derived from isophthalic acid. Poly(esters) containing Ge showed higher Tg values but lower thermal decomposition temperatures when compared with the analogous with Si.
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    Thermogravimetric analysis of poly(ester-carbonates) and poly(ester-thiocarbonates)
    (GORDON BREACH SCI PUBL LTD, 1995) Tagle, LH; Diaz, FR
    The thermogravimetric behaviour of poly(ester-carbonates) and poly(ester-thiocarbonates) derived from the diphenol esters 4-hydroxy-phenyl-4-hydroxy-benzoate, 3-hydroxy-phenyl-4-hydroxy-benzoate, 4-hydroxy-phenyl-3-hydroxy-benzoate, and 3-hydroxy-phenyl-3-hydroxy-benzoate with phosgene and thiophosgene was studied by dynamic thermogravimetry. The thermal decomposition temperatures were determined, showing that poly(ester-carbonates) are more stable than poly(ester-thiocarbonates). The kinetics parameters, activation energy, reaction order and pre-exponential factor, were determined by using the Arrhenius relationship and a computer program.
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    Thin amorphous platinum films photochemically obtained, and their potential use as modified electrodes
    (ELSEVIER SCIENCE SA, 2002) Tejos, M; Schrebler, R; Diaz, FR; del Valle, MA
    Thin amorphous nanostructured Pt films have been photochemically obtained by means of direct UV radiation (254 nm) of an amorphous Pt[CH3(CH2)(8)COCHCOC4H9](3)K film deposited on Si(100) and on ITO glass through the spin-coating technique. The product of this photolysis was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and microanalysis. After that, the film was subject to cycles for 1 h, between -0.30 and 1.20 V, in a 0.50 M H2SO4 electrolytic solution. It may be observed that the peak potential shifts in approximately 0.04 V towards less positive values for the modified system, if compared with the platinum bulk. It only showed one peak in the hydrogen discharge if compared with the two peaks in the Pt bulk. Based on these data, the ITO/Pt modified system was tested as an electrodic substrate for aniline polymerization in 0.50 M H2SO4. The polymeric deposit was obtained at lower potentials than those required when the Pt bulk is used as an electrode. (C) 2002 Elsevier Science B,V, All rights reserved.