Polyaniline emeraldine base

TABLE 1. Effect of selected dopants on the film conductivity and elongation at break for polyaniline (emeraldine base). 

The composition of polyaniline (emeraldine base) is shown in Fig. 12, and consists of alternating reduced and oxidized repeating units. Polyaniline can be switched back and forth from its insulating state to the conducting state by doping with HCl... 

F. Rodrigues, G.M. Do Nascimento, and P.S. Santos, Dissolution and doping of polyaniline emeraldine base in imidazolium ionic hquids investigated by spectroscopic techniques, Macromol. Rapid Commun., 28, 666 69 (2007). 

The Cu(II) complex with polyaniline (emeraldine base) exhibits a higher catalytic efficiency for the dehydrogenative oxidation of cinnamyl alcohol into cin-namaldehyde. Iron(III) chloride is similarly used instead of copper(II) chloride. The catalytic system is applicable to the decarboxylative dehydrogenation of man-delic acid to give benzaldehyde. The cooperative catalysis of polyaniline and cop-per(II) chloride operates to form a reversible redox cycle under oxygen atmosphere as shown in Scheme 3.4. The copper salt contributes to not only oxidation process but also metallic doping. The reduced phenylenediamine anionic species appear to be stabilized by the metallic dopants. 

There are two weak bases, ammonia and polyaniline (emeraldine base) competing for the acid. When ammonia is present, the reaction moves to the right and polyaniline is dedoped. When the ammonia vapor is turned off (removed), the reaction may move back to the left and polyaniline becomes redoped, releasing ammonia. This process involves a reversible change in the mass of the film [85] in addition to the changes in color and resistance. 

FIGURE 20.7 Cyclic voltammogram of polyaniline (emeraldine base). Colors given represent those seen at potential regions indicated. (From MacDiarmid, A., Synth. Met., 18, 393, 1987. With permission.)... 

Yang, D., and B.R. Mattes. 2002. Polyaniline emeraldine base in N-methyl-2-pyrrolidinone containing secondary amine additives A rheological investigation of solutions. / Polym Sci B Polym... 

Wang, X., et al. 2000. Corrosion protection on mild steel using polyaniline emeraldine base by solvent free technique. Polym Prepr Am Chem Soc Div Polym Chem 41 (2) 1 752. 

Jasty, S., and A.J. Epstein. 1995. Corrosion prevention capability of polyaniline (emeraldine base and salt) An XPS study. Polym Mater Sci Eng 72 565. 

Han, C.-C., and R.-C. Jeng. 1997. Concurrent reduction and modification of polyaniline emeraldine base with pyrrolidine and other nucleophiles. Chem Commun 6 553. 

Han et al. [64, 66] reported the synthesis of highly conductive and thermally stable self-doped mercaptopropanesulfonic-acid-substituted polyanilines by the concurrent reduction and substitution reaction between polyaniline and a nucleophile. These reactions were carried out on both electrochemically generated and free standing polyaniline films prepared from emeraldine base dissolved in N-methylpyrrolidinone. The electrochemically prepared films were dedoped with 5 % aqueous NaiCOs to convert them the into the emeraldine base form. The sulfonated polyaniline was prepared by reaction of a polyaniline emeraldine base film with 0.1 M 3-mercapto-l-propanesulfonic acid sodium salt in methanol under nitrogen at room temperature for approximately 14h [66]. A catalytic amount (0.01 M) of acetic acid was reported to accelerate the reaction. The resulting sulfonated polyaniline film was thoroughly rinsed with methanol, followed by 5 % aqueous NaiCOs to remove reactants. 

D. Yang, G. Zuccarello, B. R. Mattes, Physical stabilization or chemical degradation of concentrated solutions of polyaniline emeraldine base containing secondary amine additives, Macromolecules 2002, 35, 5304. 

In the present work, we used polyaniline (PANI)/polyacrylonitrile (PAN) blend to form a nonwoven mat. The PANI exists in a large number of intrinsic redox states. The half oxidized emeraldine base is the most stable and widely investigated state in the PANI family that can be dissolved in N-methyl-2 pyrohdon (NMP). The polyaniline emeraldine base (PANIEB)/polyacrilonitrile blend solution in NMP was prepared and then it was electrospun with different blending ratio. The fibers diameter, fibers morphology, and electrical conductivity of the mats were analyzed and discussed. 

Polyaniline emeraldine base could be converted to sulfonated polyaniline (Fig. le), a self-doped, water-soluble conducting polymer [27,28]. Without external doping, this polymer has a conductivity of 0.1-1 S/cm. This polymer has better thermal stability than PANI-HCl. Membranes made from this polymer could have electrochemically controllable acidity and enzyme activity. 

However, the conventional percolation threshold level of 16% has been observed in polyblends of nonconducting polyaniline (emeraldine base) with thermoplastics [154,155], polystyrene sulphonic acid [156], etc. 

TFA Trifluoroacetic acid TFE Trifluoroethanol HA Hydroxyapatite filler PEO Poly(ethylene oxide) PANi Polyaniline (emeraldine base) BDI Diisocyanatobutane DCM Dichloromethane DMAC Dimethylacetamide THE Tetrahydrofuran HEA Hexafluoroacetone HEP l,l,l,3,3,3-Hexafluoro-2-Propanol D Eiber diameter. The silk is isolated from cocoons of silkworm B. mori and degummed. The silk derived has an average molecular weight of around 9 x 10 (g/mol). 

We have prepared a series of nylon / poly aniline blends using the solvent hexafluoroisdpropanol (HFIP), which is an excellent solvent for polyaniline emeraldine base (PANI-EB), polyaniline doped with various sulfonic acids (PANI-ES) and for hi molecular weight nylon 6 and nylon 12. It was observed that conductivity and morphology of the blends varied with the compatibility of the sulfonic acid anion with the nylon. Methanesulfonic acid, butane sulfonic acid dodecylbenzene sulfonic acid and camphor sulfonic acid were used as PANI dopants and the PANI-ES / nylon blends were characterized by electrical conductivity (room and low temperature) and transmission electron microscopy. The results of these various measurements and the conclusions which can be drawn regarding morphology and conductivity of Ihe blends, will be reported. 

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