In this review, polyfuran (PFu) synthesis methods and the nucleation mechanism; the electrochemical, structural, morphological, and magnetic properties of PFu; thermal behavior; theoretical calculations on PFu, as well as its applications reported to date, have been compiled. Not only PFu homopolymers have been reviewed, but also PFu co-polymers, PFu bipolymers, and PFu composites. The results are listed, discussed, and compared. It is hoped that this assembly of all the relevant data might enhance knowledge about this conducting polymer and lead to new research fields.

No abstract

No abstract

Conductivity, electrochromism, chemical sensing, and electroluminescence are the most interesting and promising properties of conducting polymers. 1 All of those are based on the peculiar chemical structure of the polymer chain, which can change its electronic and conformational structure under external conditions. These conditions may be: chemical environment, i.e., active chemical species, pH, or different solvent; electric field, i.e., polarization in electrochemical or solid-state conditions; and other conditions that can introduce variations favorable to the polymer, for instance, optical excitation or magnetic field.Polyaniline (PANI) is one of the most stable conducting polymers and much work has gone into understanding its chemical and electronic properties. 2-5 At present it is largely accepted that insulator-metal transition of PANI is based on the acid-base chemistry of amine and imine groups. In strong mineral (and organic) acids imine groups become protonated, and their positive charges are delocalized over several monomer units along the polymer chain. Scheme I shows the chemical structures of polyaniline in its nonconductive emeraldine base (PANI-EB) and conductive emeraldine salt (PANI-ES) forms. The contranions (i.e., anions of the strong acid) are not involved in delocalization, so, their chemical nature is secondary. 6 It was recently proposed from a study of the electrochemical behavior of the quinone-hydroquinone (Qui-Hqui) redox pair on the PANI electrode in strong acid solution (1 M H 2 SO 4 ) that protonated centers of the polymer are directly involved in the charge transfer to/ from an organic acceptor. 7,8 Scheme II shows the internal and external redox transformation of/on the PANI electrode in those conditions.In our work 8 we have also proposed and discussed the structures of the reaction center (CT complex), assuming it to be the protonated imine group and Hqui (Qui) molecule with a hydrogen junction (H bridge) between them, Scheme III. While the charge-transfer process takes place through this bridge, the electrochemical kinetics of the Hqui oxidation (Qui reduction) would show a first-order dependence on the quantity of PANI deposited on the Pt electrode as was observed in Ref. 8.Following this hypothesis we have proposed that in less acid electrolytes, Hqui molecules could interact with the PANI-EB to form H bonds and in that way they themselves would protonate imine centers of the polymer electrode. Obviously, this will happen when there are not quite enough free protons in the electrolyte, i.e., when pH is above a given level.This assumption could also be valid for the polymer-molecular mixture PANI-EB ϩ Hqui prepared from an inert solvent, for instance N-methylpyrrolidinone. When the CT complex is formed between EB and Hqui, the latter has to accept a negative charge andThe impedance method was used to study the charge-transfer interaction between the polymer conducting chain (emeraldine form of polyaniline, PANI) and active molecules in solution (tetrafluorohydroquinone, 4F-Hq...

No abstract