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Electrospun polyaniline fibers synthesized by green route
No full textElectrospun polyaniline fibers synthesized by green route
P. Fronteraa, M. Lo Faroc, C .Busaccaa, P. L. Antonuccia, E. Fallettab,C. Della Pinab, M.Rossib
a: Dipartimento Meccanica e Materiali, Facoltà di Ingegneria, Università Mediterranea di Reggio Calabria , via Graziella loc. Feo di Vito 89124, Reggio Calabria, Italy. E-mail: [email protected], [email protected],
b: Dipartimento di Chimica Inorganica, Metallorganica e Analitica, Università degli Studi di Milano, Via Venezian 21, 20133 Milano, Italy. E-mail: [email protected], [email protected], [email protected],
c: CNR-ITAE, salita Santa Lucia sopra Contesse 5, 98126 Messina Italy.
E-mail: [email protected],
Nanowires of conducting polymers constitute an interesting class of materials for many applications (electronic, magnetic, biomedical and optical approaches).[1]
Electrospinning method has emerged as a promising technique to produce well aligned wires and fibers with nanometric diameters that magnifies the intrachain percolation especially in conductive polymers.[2] In our work, high purity bulk PANI was prepared by a “green” oxidative polymerization of N-4-aminophenyl aniline using hydrogen peroxide as oxidant, under mild conditions in aqueous solution.[3] The polymeric material was identified as conductive emeraldine salt by many spectroscopic techniques as FT-IR, UV-vis and X-ray diffractions.
Because of its poor solubility in common solvents, PANI cannot be directly processed by electrospinning. In this work we have operated reducing the amount of PEO in order to produce PANI wires more pure and we reported the effect of the amount of PEO added in the batches on the morphology of PANI nanofibers and on their resulting electronic conductivity. Scanning electron microscopy has been used to evaluate the morphology of the resultant electrospun fibers. Both the bulk doped PANI and the spun composite fibers have been characterized by means of the complex impedance spectroscopy (EIS) for measuring the electrical conductivity under 0 V, 0.5 V and 1 V at room temperature and static air.
[1] M. Li, Y. Guo, Y. Wei, A. G. MacDiarmid, P. y. Lelkes, Biomaterials 27 (2006) 2705.
[2] S. Ramakrishina, K. Fujihara, W. E. Teo, T. C. Lim, Z. Ma, An Introduction to Eectrospinning and Nanofibers; World Scientific, Singapore (2005).
[3] Z. Chen, C. Della Pina, E. Falletta, M. Lo Faro, M. Pasta, M. Rossi, N. Santo, J. Catal. 259 (2008) 1
One-pot synthesis of polyaniline/Fe3O4 nanocomposites with magnetic and conductive behaviour. Catalytic effect of Fe3O4 nanoparticles
No full textPolyaniline/Fe3O4 nanocomposites were prepared by a one-pot synthesis using N-(4-aminophenyl)aniline as the reagent, molecular oxygen or hydrogen peroxide as the oxidizing agents in the presence of Fe 3O4 nanoparticles (NPs) in powder and ferrofluid form. Both magnetic NPs in powder and ferrofluid form showed similar catalytic behaviour. The catalytic effect is particularly evident when molecular oxygen was used as the oxidizing agent. However, concerning the morphological aspects, only the composites prepared in the presence of ferrofluid-type Fe 3O4 NPs showed a preferential morphology of nanorods (between 30 and 110 nm in diameter). All the composites are superparamagnetic at room temperature but at low temperature they are in a blocked state. Inter-particle interactions significantly affect the magnetic properties of the composites. The electrical conductivity of the composites is about 10 -2 S cm-1, in agreement with the values obtained for polyaniline prepared by chemical route. A mechanism of the nanorods formation is proposed
Polyaniline nanofibers: towards pure electrospun PANI
No full textNanofibers of conducting polymers, as polyaniline (PANI), have received a great deal of attention by the
scientific community for their potential applications (electronic, magnetic, biomedical, optical fields). Recently the
electrospinning has emerged as a promising technique to produce wires and fibers of polymers with diameters ranging from
10 nm to 10 m. PANI has poor processability by electrospinning due to its poor solubility in common solvents, but it is
possible to spun polyaniline nanofibers adding another polymer to the organic solutions. The presence of an insulator
copolymer decreases the fibers/wires conductivity.
In this work we report the preparation of highly pure polyaniline fibers by electrospinning process.
PANI powder has been characterized by FT-IR, UV-VIS, and X-Ray diffraction. The spun sample obtained have been
characterized by SEM to evaluate the wire morphology and complex impedance spectroscopy (EIS) in order to measure the
electrical conductivity.
We observed that, reducing the amount of PEO in the PANI/PEO blend organic solution, the fiber sizes decreased from
421nm for higher content of PEO (PANI: PEO= 1: 1, w/w) to 230 nm (PANI: PEO= 1: 0.1, w/w).
The way to collect the fiber has been also investigated. Using a rotanting collector we observed a stretching effect on the
fibers which promotes a narrow distribution of fibers dimension with respect to the fibers obtained with static collector
Facile synthesis of polyaniline using gold catalyst
No full textThe oxidative polymerization of aniline was investigated using H2O2 as an oxidant and metallic gold as a catalyst. In the form of colloidal nanoparticles, gold produces the conductive polyaniline only in a low yield, whereas when supported on carbon and titania, it improves the polymerisation reaction. For an Au/TiO2 catalyst, a synergistic effect between the metal and the support has been demonstrated that allows the production of polyaniline at high yield (70%). Morphological aspects, derived by TEM and SEM techniques, allow identification of the polymeric material in form of nanospheres 45-600 nm in diameter
Electrospinning of Polyaniline: Effect of Different Raw Sources
No full textNanofibers of conducting polymers, as polyaniline (PANI), have received a great deal of attention by the scientific community for their potential applications (electronic, magnetic, biomedical, optical fields). Recently the electrospinning has emerged as a promising technique to produce wires and fibers of polymers with diameters ranging from 10 nm to 10 μm. PANI shows poor processability by electrospinning due to its low solubility in common solvents. However, it is possible to spin polyaniline nanofibers adding another polymer to the organic solutions, generally an insulator, necessary to increase the viscosity of the polymeric solution to be spun. Unfortunately, the presence of an insulator copolymer decreases the fibers conductivity. The key factor to obtain fibers of good quality (high conductivity and a narrow distribution of the diameters) is to reduce the amount of insulator copolymer in the spun process. Accordingly, we prepared raw PANI following different synthetic methods to be compared, aiming at the best optimized protocol in terms of easy solubility and enhanced spinning behavior of the polymers achieved. All the materials have been characterized by FT-IR and UV-VIS spectroscopies. The spun samples obtained have been characterized by SEM to evaluate the fiber morphology and complex impedance spectroscopy (EIS) in order to measure the electrical conductivity
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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