Synthetic Metals (v.158, #5)
Polyfuran conducting polymers: Synthesis, properties, and applications
by M.J. González-Tejera; E. Sánchez de la Blanca; I. Carrillo (pp. 165-189).
In this review, polyfuran (PFu) synthesis methods and the nucleation mechanism; the electrochemical, structural, morphological, and magnetic properties of PFu; thermal behavior; theoretical calculations on PFu, as well as its applications reported to date, have been compiled. Not only PFu homopolymers have been reviewed, but also PFu co-polymers, PFu bipolymers, and PFu composites. The results are listed, discussed, and compared. It is hoped that this assembly of all the relevant data might enhance knowledge about this conducting polymer and lead to new research fields.
Keywords: Polyfuran; Conducting polymers; Physico-chemical properties
Thermal treatment under reverse bias: Effective tool for polymer/fullerene bulk heterojunction solar cells
by Yan Li; Yanbing Hou; Yan Wang; Zhihui Feng; Bin Feng; Lifang Qin; Feng Teng (pp. 190-193).
The effect of post-thermal treatment under reverse bias on the performance of bulk heterojunction photovoltaic cells based on poly[2-methoxy-5-(20-ethylhexyloxy)- p-phenylene vinylene] (MEH-PPV) and fullerene (C60) composites is investigated. The experimental results show that treated devices deliver increased short-circuit current density ( Jsc) and conversion efficiency ( ηp) values. Especially, for the device annealed under the bias of −6V, the short-circuit current density ( Jsc) and the conversion efficiency ( ηp) are enhanced by a factor of 6 and 5.4, respectively. It is concluded that the enhancement of charge mobility induced by polymer chains modified orientation along the direction of electric field leads to a significant increase in the photovoltaic parameters.
Keywords: PACS; 72.40.+w; 72.80.LeA. Polymer; D. Photovoltaic
Optical and electron-deficient properties of poly[2,7-(9,9-dihexylfluorene)-Co-Bi-pyridine]: A combined experimental and theoretical study
by Wu Zhang; Bing Yang; Ping Lu; Mao Li; Leilei Tian; Yuguang Ma (pp. 194-199).
A series of well-defined poly[2,7-(9,9-dihexylfluorenyl)-co-bipyridinyl] [F-(BPY) x] with varied BPY (bipyridine) unit contents from 0 to 50% were synthesized using palladium(0) catalyzed Suzuki cross-coupling reactions, and well characterized using1H NMR, IR, and GPC. Their photophysical and electrochemical properties were investigated. These copolymers showed pure blue photoluminescence (440nm) in dilute solutions with the fluorescence quantum yield >0.6. Electron-affinity potentials (LUMO levels) of these polymers estimated from cyclic voltammetry were significantly decreased with the increase of BPY content in the polymer backbone, and a level of 2.43eV for alternating BPY-fluorene polymer (50% BPY) was achieved, making them good candidates for electron injection and transport materials in EL devices. A further great decrease in LUMO level up to 2.99eV was found when Zn2+ was chelated into polymers. The experimental observations were supported by the quantum chemical calculations on these polymers, which provided the proof for the intuitive notion of an intramolecular charge transfer band in polymer chain.
Keywords: Conjugated polymers; Electron-deficient properties; Bipyridine; Zinc cation chelation; Quantum chemical calculations
Chemical oxidative polymerization of anilinium sulfate versus aniline: Theory and experiment
by Gordana Ćirić-Marjanović; Elena N. Konyushenko; Miroslava Trchová; Jaroslav Stejskal (pp. 200-211).
The mechanism of the oxidative polymerization of anilinium sulfate with ammonium peroxydisulfate in aqueous medium has been studied by the AM1 and MNDO-PM3 semi-empirical quantum chemical methods combined with the MM2 molecular mechanics force-field method and conductor-like screening model (COSMO) of solvation. The aniline nitrenium cation is the main reactive electrophilic species generated in the initiation phase. It is proposed that the rate and regioselectivity of dimerization is governed by the electrophilic aromatic substitution reaction of non-protonated aniline molecules with aniline nitrenium cations. 4-Aminodiphenylamine and its fully oxidized form, N-phenyl-1,4-benzoquinonediimine, are the main dimeric products. The dominant aniline trimer and tetramer are shown to be linear, N–C coupled, with the prevalence of the para-substitution pattern. The mechanism of oxidation of anilinium sulfate is compared with that of non-protonated aniline molecules; the latter yield also branched trimers and tetramers that are subsequently oxidized to phenazine constitutional units. The differences in morphology of the polyanilines obtained by the oxidation of anilinium sulfate and aniline, granules, nanotubes or nanorods, and in molecular structure reflected by infrared spectra are discussed with respect to the formulated comprehensive mechanistic scheme of the early stages of both anilinium cation and aniline oxidation.
Keywords: Aniline; Anilinium cation; Aniline nitrenium cation; Aniline oligomer; Nanorods; Polyaniline