EB with Bronsted Acids HA

In an important discovery in the early 1990s, Cao and coworkers154 found that organic solvent solubility can be imparted to conducting PAn salts by the incorporation of surfactant-like dopant acids (HA). For example, by doping EB with large bifunctional protonic acids such as HCSA or DBSA, it is possible to solubilize fractions of these polymers in their fully doped state into solvents such as m-cresol, chloroform, toluene, and xylene. This solubilization is caused by the hydrocarbon tail in the dopants, while the sulfonate (SO,-) head forms an ionic bond with radical cation NH+ sites on the PAn chains. There is some debate as to whether this approach pro- 

It has recently been shown that acid doping of EB can also be carried out in the solid state.160 For example, the mechanical blending of stoichiometric amounts of solid EB and HCSA or picric acid leads to electrically conducting PAn/HA salts. 

Water-soluble ESs can also be prepared by this acid-doping technique. For example, doping of EB with phosphonic acid containing poly(ethyleneglycol)monoethyl ether (PEGME) as a hydrophilic tail gives a mildly conducting PAn that is soluble (or dispersible) in water.161 

With the water-soluble poly(o-methoxyaniline) (POMA), Mattoso and coworkers162 have reported the self-assembly of multilayer conducting polymer films by depositing alternating layers of the POMA cation and polyanionic dopants such as poly(styrenesulfonate) and poly(vinylsulfonate) onto a glass substrate. This concept has been further developed with POMA by employing the anion of poly(3-thiopheneacetic acid) as the polyanionic dopant, giving novel self-assembled films in which both the cationic and anionic components are electroactive polymers.163 

We have employed a related approach in generating films containing alternating layers of the anionic, water-soluble sulfonated polyaniline PMAS 9 and the polycation, poly(vinylpyridine).164 The analogous self-assembly of multilayer films of the sulfonated SPAN 8 and the light-sensitive polycation, diazoresin, has also been described recently.165 

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Postpolymerization modification — enhancing functionality Covalently substituted polyanilines Doping of EB with Bronsted acids, HA Incorporation of chiral dopant anions or cations Doping of EB with Lewis acids Doping of EB with organic electron acceptors Ion implantation Structure of Polyaniline... 

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