Stretchable interconnects are fundamental building blocks of flexible macroelectronics. Currently, thin metal films are widely used in electronic circuits as interconnects. Not like their bulk counterpart, however, such thin films of metal rupture at very small strain (<1%).>

One possible solution for stretchable interconnects might be conducting polymer. The first conducting polymer was discovered in 1977. Since then, enthusiasm has been gathering among scientists. As a result, several practical conducting polymers had become available by mid-1990s. Although these polymers are conductive, however, they are not truly metallic. For example, the hallmark of metallic conductivity—increasing conductivity as temperature decreases—has not been demonstrated by these conducting polymers at temperatures over the full range below room temperature.

Recently, Korea and US scientists made thin films of polyaniline that show both the optical and electrical properties characteristic of metals by a new technique ( self-stabilized dispersion polymerization (Nature 441, 65-68 (4 May 2006)). The polyaniline films produced by this new technique are more structurally ordered than those made by conventional methods. As a result, these new films show a two and half fold increase in conductivity as temperature decreases from room temperature to 4 Kelvin. Also the optical reflectivity of these polyaniline films fits that of a metal.

Although the conductivity of these polyaniline films is still about two orders of magnitude lower than that of typical metals, truly metallic polymers would potentially diversify possible applications of flexible macroelectronics.

For more details, read the Nature paper

(Image credit: Lee et al.)