Papers by Keyword: Pyrrole

Abstract: The aim of these comparative studies consists of synthesis and characterization of membrane assemblies from cellulose acetate (CelAc) and acrylic acid (AA), using as dopant in-situ generated pyrrole–aniline (Py–AN) copolymer intended for use in fuel cells fabrication. The synthesis was conducted through free radical polymerization in a semi-homogeneous system and the casting method was used to form the solid polymer membranes. In selecting the optimal compositional parameters, the influence of the molecular size of the majority matrix component was also observed. These membrane assemblies were studied using FT-IR spectroscopy, UV-Vis spectroscopy, and X-Ray diffraction analysis which highlighted the structure–composition dependence. With the electrochemical impedance spectroscopy the ionic conductivity of the membrane was determined, in order to evaluate the PEM fuel cell performance. In case of thicker membranes, there is an increase in ionic conductivity values over those of lower thickness, which is due to short-order structural order. Also, a superunitary Py:AN is more favorable to conductivity increase than a less than one ratio.

Abstract: Adsorption of pyrrole on the Si(111)-7×7 surface was investigated using scanning tunneling microscopy (STM). Template-induced molecular corral structure was observed at room temperature though the N-H bond cleavage. At the substrate temperature of 130 °C, the pyrrolyl adsorbates were observed by STM with reserving the 7×7 substrate. However, the self-assembly of the molecular corral structure was disarranged at 130 °C. Then, pyrrolyl group was decomposed or desorbed from the surface at the substrate temperature of 200 °C. The defect-induced attachment of pyrrole was also observed.

Abstract: Abstract. During the last decade, research on intelligent textile systems progressed steadily. Today, science is focusing on full integration of electronics into textiles. E-textiles function like their rigid electronic companions but keep their textile properties. To interconnect components within the system, textile structures need to be equipped with electro-conductive properties. For flexible solar cells or fibrous transistors, electro-conductive coatings are applied. Transistors, acting as electrical switches, are essential for realizing fully integrated intelligent textile systems. By electroless deposition of pyrrole and copper on polyester fibres, conductivity is achieved. A DC conductive gate electrode is designed. In this paper, the development of the gate layer within the fibrous transistor is described. Ideal pH and optimal reaction time are determined as well as the effect of variation in fibre diameter is investigated. A reproducible polypyrrole layer has been obtained. Ideal reaction time was 180 minutes at a temperature of 278K. The electroless copper coating process on the polypyrrole layer showed optimal results when the substrate was immersed into the plating bath coated for 6 minutes at a pH of 13. Analysis through resistance measurements has been completed.

Abstract: The pyrene/pyrrole copolymer (Pn/Py copolymer) has been sucessfully synthesized by the facile chemically oxidative copolymerization. UV-vis and FT-IR spectra are used to investigate the molecular structure of the copolymer. The results show that pyrene and pyrrole units in the copolymer chain are interconnected via α, α-coupling to form a linear structure. At the same concentration, the copolymer solution exhibits the strongest green fluorescence with a maximum emission at 503 nm and a large stokes shift of about 113 nm by fluorescence spectrometer. The excellent fluorescence of Pn/Py copolymer may be due to its better planar molecular structure and higher large π-conjugation, that is confirmed by UV-vis spectra and molecular simulation.

Abstract: Several novel organic material were Prepared by condensation between p-aminophenyl methyl keton, 3,5-Dicholoro-4-aminophenyl methyl keton and 5-Dibromo-4-aminophenyl methyl keton and pyrrole. The reaction condition has been optimized. The structure was characterized by 1HNMR and elemental analysis.

Abstract: The thermodynamics properties of synthesize reactions of Ph3SnR (R= N (C4H4), N(C8H6), C6H5) and CpM(CO)2CY(M=Cr, Mn; Y=S, Se), the total energy and Mulliken atomic charges of the compound products M(CO)2CY-Ph3XR(M=Cr, Mn; X=Sn, Ge; Y=S, Se; R= N(C4H4), N(C8H6), C6H5) with different substitute positions on the benzene ring were investigated using DFT method. The calculation results of total energy showed that the ligand was determinant of the favourable substituted position and the central metal of two different type ligands CpCr(CO)2CY(Y=S, Se) and CpMn(CO)2 CY(Y=S, Se) was the key factor; whether the reactants Ph3SnR( R= N(C4H4), N(C8H6)) and Ph3SnR( R= C6H5) had the pyrrole or not had effect on the character of substituted position. The Mulliken atomic charges of central metal Sn and Ge showed that the atom charge value of Sn and Ge of M(CO)2CY-Ph4X was smaller than M(CO)2CY-Ph3XN (C4H4) and M(CO)2CY-Ph3XN(C8H6) (M=Cr, Mn; X=Sn, Ge; Y=S, Se) correspondingly; electron-donating trend of Ph3GeR group was stronger than that of Ph3SnR group; the pyrrole group had some conjugation effects which made the electronic distribute more even. The calculation results of thermodynamics properties of the synthesize reactions of Ph3SnR(R=N(C4H4), N(C8H6), C6H5) and CpCr(CO)CS showed that the reaction possibility was small at the general condition; ligand CpMn(CO)2CY(Y=S, Se) was more favorable to the reaction than CpCr(CO)2CY(Y=S, Se); different substituted positions would have effect on the reaction possibility apparently. Decreasing temperature would be favorable to the possibility of the reactions, but increasing temperature might be favourable to the rate of reactions.

Abstract: Polypyrrole (Ppy)-coated viscose fibers have been prepared by vapor phase and liquid phase pyrrole deposition technique, respectively. Comparative morphological and electrical property analysis was carried out on the viscose fiber prepared with both vapor and liquid phase processes. The result showed the configuration of Ppy coatings and electrical property had a strong relation with the deposition technique. Ppy-coated viscose fiber prepared by vapor phase show a high uniform polypyrrole coatings, fine Ppy granular structure, lower electrical resistance, and good fastness performances to abrasion.

Abstract: The electronic structures of oligomers of pyrrole have been calculated using the extended Hückel tight-binding program. The energy diagrams are shown for oligomers as the number of the repeating unit in the oligomers increases from 1 to 16. The relationship between the energy gap of the oligomers and the number of the repeating unit in the oligomers is established. Blue-green photoluminescence and electroluminescence from one-dimensional polypyrrole are predicted.