Polyaniline: Solutions, Films and Oxidation State

Abstract

The emeraldine oxidation state of polyaniline in its base form, “emeraldine base” can be solution-processed to yield large flexible films which can be doped to the metallic conducting regime (σ ∼ 1-5 S/cm). The approximate solubility of emeraldine base at room temperature in 80% aqueous acetic acid, 60% and 88% aqueous formic acid, dimethyl sulfoxide (DMSO), dimethylformamide (DMF) and N-methylpyrrolidinone (NMP) have been determined. Both emeraldine base and emeraldine hydrochloride can be sublimed onto a variety of substrates to produce high quality, ∼2000 Å thick films which are similar but not identical to emeraldine base. Emeraldine base, which is slowly oxidized by air, can be reconverted to the emeraldine oxidation state by treatment with dilute aqueous acids.