Novel Synthesis, Characterization, and Physical Properties of Self-Doped Sulfonated Polyaniline by Copolymerization between p-Aminodiphenylamine and o-Aminobenzenesulfonic Acid

Abstract

ABSTRACT:Sulfonated polyaniline has been synthesized by a novel method, in which p-aminodiphenylamine (p-APA) and o-aminobenzenesulfonic acid (o-ABS) are copolymerized. The copolymers produced have the same composition even though the feed ratios (p-APA/o-ABS) are varied. This fact as well as the results of elemental analysis, infrared (IR), ultraviolet-visible (UV-Vis), 1 H nuclear magnetic resonance (NMR), and X-Ray photoelectron spectroscopic (XPS) spectra show that the copolymer has a so-called one-to-one structure of p-APA and o-ABS. XPS spectra reveal that three kinds of nitrogen atoms exist in the copolymer, namely, amine nitrogen, radical cation type nitrogen, and iminium ion type nitrogen. One third of the whole nitrogens is self-doped. Conductivity of the copolymer is independent of pH, but lower than that of doped polyaniline probably because of the presence of sulfonyl acid groups. The copolymer is soluble in an aqueous alkaline solution owing to sulfonyl acid groups. Electronic spectra of the mixtures of p-APA and o-ABS suggest that the 1: 1 charge-transfer complex is formed between p-APA and o-ABS. Oxidizing agents are considered toreact with the charge-transfer complex to form the one-to-one copolymer of p-APA and o-ABS.KEY WORDS Water-Soluble Conductive Polymer I Self-Doped Sulfonated Polyaniline I p-Aminodiphenylamine I o-Aminobenzenesulfonic Acid I Charge-Transfer Complex I Copolymer I Good Processability I Among the aromatic conductive polymers such as polyacetylene, polythiophene, polyaniline, and polypyrrole, polyaniline has been most successfully applied to practical use, since it is stable under air and soluble in solvents such as N-methyl-2-pyrrolidone (NMP). For example, the applications to antistatic agents, electromagnetic shielding materials, secondary batteries, 1 -3 redox reaction catalysts, 4 -6 gas sensors/ gas separation membranes,8 artificial mascle, 9 etc. have been examined. However, there are still big problems in processability of polyaniline.The attempts to improve processability by means of altering polyaniline into its derivatives by introducing alkyl groups into the aromatic ring and/or the nitrogen site were reported so often. 10 -12 However, this introduction always causes the decrease of electric conductivity in compensation for increase of processability. In the meantime, the precursor method was reported on processing of polyphenylene for the purpose of improving processability. 13 In this method a film of polyphenylene was obtained by heating a film of the precursor having good processability. However, there was no reports on the application of the precursor method to prepare a polyaniline film. Recently we have succeeded in preparing a film ofpolyaniline by heating a cast film ofpolyanthranilic acid which is a soluble precursor of polyaniline.14-15On the other hand, much attention has been paid to sulfonated polyanilines, 16 -34 because it is stable and soluble even into water when self-doped. In a conventional method, sulfonated polyaniline was prepared by the re...

Synthesis, Structure, and Chemical Properties of Lithium Salts of Poly(2-methoxyaniline-5-sulfonic acid)

“…The anode potentials were somewhat lower than those observed in HCl(aq). 1b The two oxidation peaks were coupled with cathodic peaks, E pc (1) and E pc (2), at -0.28 and 0.34 V vs Ag + /Ag, respectively. During the two step oxidation, about 0.5 positive charge was stored per the repeating monomeric unit.…”

“…During the two step oxidation, about 0.5 positive charge was stored per the repeating monomeric unit. According to the lithiation, the peak potentials, E pa (1) through E pc (2), of PAS(Li)s shifted as summarized in Table 1. For PAS and PAS(Li)s, the green polymer film changed to blue after the electrochemical oxidation (or p-doping) and returned to green after passing the E pc ( 2) peak (or depoing peak).…”

“…Sulfonated polyanilines (SPANs) have attracted interest due to their unique electrochemical properties, improved processability, and potential industrial applications . Recently, various SPANs have been synthesized by oxidative, electrochemical, and enzymatic polymerizations and graft reactions on amine nitrogen. , Application of SPANs as useful materials for rechargeable batteries, light-emitting diodes, − and patterning on a wafer has also been developed owing to their self-doping behavior to show high electrical conductivity and intriguing optical properties. Self-doping behavior of sulfonated π-conjugated conducting polymers is the subject of recent interest. , …”

An Electrochemical Study of Two Self-Dopable Water-Soluble Aniline Derivatives: Electrochemical Deposition of Copolymers

“…The radical-radical coupling, proton release, and further electrochemical oxidation steps lead to the oligomers generation. The high solubility of monomers and polymers based on N- alkylaniline substituted with acidic groups in organic medium and even in water is due to the chain length of the alkyl group [ 15 ] and to the presence of the acidic groups such as carboxyl [ 16 – 20 ], sulfonic [ 4 – 8 , 21 – 25 ] and phosphoric [ 26 ]. Furthermore, the acidic groups can react with imine nitrogen to form polarons, which are the charge carriers of doped PAni.…”

Copolymerization of aniline and 4,4′-diaminodiphenyl sulphone and characterization of formed nano size copolymer

“…The conductivity of self-doped polyaniline synthesized via chemical copolymerization of aniline and o-amino benzenesulfonic acid was reported to depend on pH in the range, 0-3 [10]. The self-doped sulfonated polyaniline was prepared chemically by the copolymerization of p-aminodiphenylamine and o-aminobenzenesulfonic acid [11]. The conductivity of this copolymer, 4 × 10 −5 S cm −1 , was independent of pH in the range 1-7.…”