Electrically conducting fibers made from rigid rod polymers

New multifunctional polymer fibers and films having high electrical conductivity plus high strength and stiffness have been prepared by several novel techniques. The resulting fibers may have strengths up to 0.5 GPa and room temperature conductivities up to 3 S/sec. All have a matrix of a rigid-rod polymer, and all have a synthetic metal phase dispersed throughout them. Host polymers are poly(p-phenylene terepthalamide) (PPTA), which is essentially DuPont's Kevlar^R, or poly(p-phenylene benzobisthiazole) (PBZT), and guest synthetic metals are oxidized phthalocyanines. Key to this work has been our ability to exercise specific control over microstructure, which, in turn, determines what will be the final physical properties. This control has been achieved by proper use of known (or estimated) phase relationships and predicted phase transformation kinetics. In some cases the guest species undergoes phase separation during the solidification process itself; in other cases a microstructure is established firstly with the host polymer and then the synthetic metal phase is caused to form inside it. Quantitative modelling of conductivity-composition or strength-composition relationships have been successfully accomplished, based in part on careful charge transport and thermopower measurements.