Polyaniline Exhibiting Stable and Reversible Switching in the Visible Extending into the Near-IR in Aqueous Media

Spun-cast films comprising polyaniline (PANI) that is template synthesized with poly(2-acrylamido-2-methyl-1-propanesulfonic acid), PAAMPSA, can be reversibly switched between emeraldine salt, leucoemeraldine base, and for the first time, pernigraniline base states in aqueous media at near-neutral pHs. Transitions between the green, transparent and violet states occur within 1-10 s, comparable to the electrochromic switching times reported for thin films deposited via layer-by-layer approaches. Solvent annealing in dichloroacetic acid induces structural rearrangement within PANI-PAAMPSA, resulting in significantly improved stability and reversibility upon repeated cycling, and moreover, imparting tunable polyelectrochromism that extends into the near-infrared (1100 nm).