Nature of the Dopant Acid HA

It has been shown that addition of polyelectrolytes to the polymerization solution can result in the incorporation of these larger molecules as dopants even when the acid is in excess.24 Others have shown that the addition of inert salts (e.g., LiCl, CaCl2) to the acid electrolyte can result in significant increases in molecular weight up to 160,000 gmol-1.25 

A significant development in PAn chemistry was our report26,27 of the first optically active PAn s, prepared through the electrochemical polymerization of aniline in the presence of the chiral dopant acids (+)- or (-)-10-camphorsulfonic acid (HCSA). Films of the emeraldine salts PAn/(+)- HCSA and PAn/(-)-HCSA can be 

The converse approach to inducing chirality into conducting polymer chains, namely, the incorporation of an optically active cation, has also been successfully employed in our laboratories to produce the first optically active water-soluble sul-fonated PAn. Poly(2-methoxyaniline-5-sulfonic acid) has been prepared in optically active form through the electropolymerization of 2-methoxyaniline-5-sulfonic acid in the presence of (/ )-(+)- or (.S )-(-)-l-phenylethylamine.29 The optical activity and electroactivity of the chiral sulfonated PAn s are retained when immobilized on poly(4-vinylpyridine) (see Chapter 5). 

Acetonitrile was also used as the solvent for the first successful synthesis of a PAn/PPy copolymer via galvanostatic (constant-current) electropolymerization of mixtures of aniline (0.5 M) and pyrrole (0.1-1.0 M) in acetonitrile solvent in the presence of CF3COOH as acid and tetraethylammonium tetrafluoroborate as supporting electrolyte. Differential scanning calorimetry and Fourier transform infrared (FTIR) measurements confirmed that the electrically conducting product was a mixture of PAn, PPy, and a random PAn/PPy copolymer.36 

Ionic liquid electrolytes have recently been used for the electrosynthesis of PAn.37 The rate of polymerization of aniline was found to be high, and adhesion of the conducting polymer product to the metal electrode was enhanced. 

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