Formation of conductive polyaniline fibers derived from highly concentrated emeraldine base solutions

The high molecular weight (M-n>30,000, M-w>120,000) form of emeraldine base (EB) may be dissolved at concentrations exceeding 20% (w/w) in organic solvents for periods of time sufficient to dry-wet spin solid fibers. This result is due to the combination of a gel-inhibitor (GI) with the polymer/solvent solution. The GI/EB complex disrupts hydrogen bond formation between EB chains in the concentrated EB solutions and thereby lowers the solution viscosity and increases the gelation time. The as spun fiber exhibits good mechanical strength and high conductivities, and both physical properties are further improved by drawing the fiber to four times its initial length. Doping the fibers with inorganic mineral acids significantly reduces fiber strength, while doping with certain organic acids, such as benzene phosphinic acid, preserves mechanical properties and high conductivity values. All of the fully doped fibers show temperature activated conductivity. No detectable crystallinity was observed by measurements with a wide angle XRD technique.