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Title: Co-existence of external protonation and self-doping in polyaniline
Authors: Neoh, K.G. 
Kang, E.T. 
Tan, K.L. 
Issue Date: 1-Sep-1993
Citation: Neoh, K.G.,Kang, E.T.,Tan, K.L. (1993-09-01). Co-existence of external protonation and self-doping in polyaniline. Synthetic Metals 60 (1) : 13-21. ScholarBank@NUS Repository.
Abstract: Polyaniline which possesses two simultaneous modes of doping, external doping by ClO4 - anions and self-doping by -SO3 - groups, has been synthesized by three different methods. In each of the methods, the self-doping is accomplished by the copolymerization of metanilic acid and aniline using either (NH4)2S2O8 or Fe(ClO4)3·9H2O as oxidant. In method I external protonation by HClO4 occurs during the polymerization process while in methods II and III treatment by HClO4 is carried out after the polymerization step. The effects of oxidant/monomer ratio and metanilic acid/aniline ratio on the physicochemical properties of the copolymers are investigated and comparisons are made with the self-doped polymer obtained from the sulfonation of polyaniline. Experimental techniques used for characterization of the polymers include X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) absorption spectroscopy, ultraviolet-visible (UV-Vis) absorption spectroscopy, elemental analysis, thermogravimetry and four-probe measurements. Under the conditions investigated, self-doping can constitute up to about half of the doping of a 50% protonated polymer. The external dopant, ClO4 - anions, are thermally less stable than the -SO3 - groups of the incorporated metanilic acid units. The latter as well as the -SO3 - groups covalently bonded to emeraldine base through sulfonation undergo thermal decomposition at a lower temperature than metanilic acid itself. © 1993.
Source Title: Synthetic Metals
ISSN: 03796779
Appears in Collections:Staff Publications

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