Alkyl- and Alkoxy-Substituted PAns

A wide range of alkyl- and alkoxy-substituted PAn s of the general types 6 and 7 have been synthesized by the chemical or electrochemical oxidation of appropriately substituted aniline monomers.133 Such substitution imparts markedly improved solubility in organic solvents to the emeraldine salt products compared to the parent (unsubstituted) PAn/HA salts. The poly(2-methoxyaniline) (POMA) species, in particular, has been the subject of extensive studies.134 137 This species has the additional attractive feature of being soluble in water after being wet with acetone. 

The substituted PAn products often have much lower molecular weights than the parent unsubstituted PAn, although Mw values as high as 400,000 g mol-1 have been reported for POMA by controlled chemical polymerization at -40°C.58 This improvement in processability for substituted PAn s is also generally gained at the expense of a large decrease in electrical conductivity, due to twisting of the polymer chains from planarity by the bulky substituents. 

Oxidative polymerization of substituted aniline monomers is frequently more difficult than that of aniline. A significant recent advance has therefore been the 

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