Low Tg, Stretchable Polyaniline of Metallic-Type Conductivity: Role of Dopant Engineering in the Control of Polymer Supramolecular Organization and in the Tuning of Its Properties

Doping of polyaniline with a new family of protonating agents, namely sulfosuccinates with alkyl or alkoxy substituents, is discussed. The resulting polyaniline-sulfosuccinates exhibit a lamellar type structural organization in which stacks of polymer chains are separated by dopant anions. Although structurally similar to previously studied polyaniline-sulfophthalates, polyaniline-sulfosuccinates are better ordered and exhibit better physical properties. In particular, they exhibit metallic-type conductivity down to 210 K and they can be stretched at room temperature to elongations at break, Δ l / l o, approaching 200%. Mechanical stretching does not affect the temperature range of the metallic conductivity, however, it does induce a 4-fold increase in the room-temperature conductivity of the polymer. Low T g of polyaniline-sulfosuccinates is also the origin of the low temperature thermochromism a phenomenon reported so far only for polyaniline-sulfosuccinates and polyaniline-sulfophthalates. Finally, accelerated aging tests carried out at a temperature of 408 K, in ambient conditions, have shown that polyaniline doped with di-(2-butoxyethyl) ester of sulfosuccinic acid is thermally more stable than poly(3,4-ethylenedioxythiophene) doped with ferric tosylate (Fe III (Tos) 3 ) the system considered so far as the most stable of all conducting polymers.