Soluble n-doped polyaniline: Synthesis and characterization

We report a novel soluble n-doped polyaniline in dimethyl sulfoxide (DMSO), which is obtained by doping the emeraldine base type polyaniline with the strong reductant, KH or NaH. At room temperature, it shows a broad strong new optical absorption peak above 1100 nm, indicating the formation of a new energy band within the energy gap, and has a conductivity of 10(-1)-10(-2) S/cm, a spin density of 3.4 x 10(20) (for KH-doping) and 4.3 x 10(19) spins/g (for NaH-doping), which are close to those of self-acid-doped polyanilines, and a magnetic susceptibility of (4.6-7.2) x 10(-3) emu/mol of ring, which is 2 orders of magnitude higher than that of acid-doped polyaniline. When exposed to air, the conductivity decreases rapidly by 6-7 orders of magnitude within 90 s due to undoping by moisture. An n-doping mechanism is proposed, from which the n-doping can also be considered as a direct doping on the oxidized form of polyaniline (pernigraniline) by the alkali metals K and Na.