PAni and PAni blends - an organic metal:

The following 2 selected papers are the results of a cooperation between 2 very different research groups - the one around G. Nimtz (II. Physikalisches Institut der Universität der Köln), the other around B. Wessling (industrial research at Zipperling). The first group found out about the quantum mechanical limitations of conductivity in mesoscopic particles of conventional metals (like indium, gold, titanium), the second group found limitations in conductivity in conductive polymers, like PAni. Then, we began to cooperate in 1990.

G. Nimtz, A. Enders, P. Marquardt, R. Pelster, B. Wessling

Size-limited conductivity in submicrometre metal particles.
Similarities with conducting polymers?

Synth. Met. 45 (1991), 197 - 201

The first publication describes the beginning of the idea (grown between the two research groups) and first experiments according to which conductive polymers might be understood as real metals, which have some limitations due to their mesoscopic properties - a phenomenon observed for other conventional metals, too, if their individual metallic particles are smaller then 1 micron. At this mesoscopic scale quantum phenomena take place.

R. Pelster, G. Nimtz, B. Wessling

Fully protonated polyaniline: Hopping transport on a mesoscopic scale

Phys. Rev. B, 49, 12718 - 12723 (1994)

The second publication is describing the results of a broad joint study showing that this hypothesis is indeed helpful. PAni could be confirmed to have 10 nm small primary particles*, containing a metallic core (8 nm) and a shell acting as a barrier. The elctronic wave functions can be described as shown below.

the morphology model (crystalline metallic core and amorphous shell
building the primary particles of PAni) is schematically compared
with the electron wave density and the barrier height for the tunneling process

Click on figure above for more details

* cf "STM investigation" and other literature about morphology