Undoped, Non-conjugated Radical Polymer Glasses with High Electrical Conductivity Values

Radical polymers have shown promise with respect to their application as transparent conducting macromolecules; however, their ultimate electronic performance has been stymied due to the disorder associated with their solid-state packing. In order to create an amorphous radical polymer with a glass transition temperature near room temperature poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO) was synthesized. In generating a redox-active macromolecule with a flow temperature far-removed from the degradation temperature of the radical sites within the polymer, annealing of the radical polymer thin film resulted in the formation of locally-ordered (yet non-crystalline), high-conductivity domains. Because of this local order in the glassy state, a greater than 1,000-fold increase is observed in the electrical conductivity of PTEO relative to all other reports of electrical conductivity in radical polymers. Moreover, the ultimate conductivity of ~20 S m^-1 places this undoped polymer conductor in the same regime as many grades of commercially-available, chemically-doped conducting polymers. Thus, these data open new insights into the physical mechanism of charge transport in radical polymer thin films, and provide a means by which to probe local order in glassy polymers.