Conductive polymers via controlled pyrolysis

Another method of inducing conductivity in polymers involves modifying their intrinsic bulk properties by pyrolysis. This method was one of the earliest used to impart conductivity. These early conductive polymers were based on refractory pyropolymers, which converted to graphite-like materials and were very difficult to characterize both 

While polymers rendered conductive by pyrolysis were largely dismissed with the discovery of conduction via doping, they are now receiving increasing interest again, particularly with a view to practical application since they have the benefit of being environmentally stable. 

Some efforts have now also been made to elucidate the conduction mechanisms in this type of material. It appears that as pyrolysis occurs, a planar polycondensed ring structure develops that has a much extended conjunction and thus a greater degree of p-orbital delocalization and therefore electron itineracy. The pyrolysis is also believed to increase the number of charge carriers by the formation of free radicals. 

Unlike many doped conductive polymers, the electrical conductivity of these polymers is environmentally stable. Exposure to air for two years and water for 80 days produces little change in the conductivity. Potential applications proposed for this type of polymer include use as a matrix for advanced composites, and in electromagnetic interference shielding and electrostatic dissipation materials. 

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