2.2. Cathodic Electropolymerization 4732 2.2.1. Electropolymerization of PPXs and PPVs 4732 3. Charging-Discharging of Conducting Polymers 4733 3.1. Redox Properties of Oligomers and Polymers 4733 3.2. Specific Phenomena of n-Doping 4739 3.3. Conductivity in Charged Systems 4740 4. Controlling the Electropolymerization Process 4742 4.1. Influence of the Polymerization Technique 4742 4.2. Influence of Experimental Conditions 4743 4.3. Electropolymerization in Novel Electrolytic Media 4745

Electrochemistry of Conducting Polymers—Persistent Models and New Concepts†

Over the past twenty years, polypyrrole has appeared as the
most extensively studied conducting polymer. However, despite the volume of
work already done in this area, there has been little focus put on the
mechanism of polypyrrole synthesis, especially concerning the most
efficient method, electropolymerization. Numerous analytical techniques
have been used to study polypyrrole electrodeposition and/or doping.
However, the mechanism itself is still a controversial subject as there is
not one mechanism which is universally accepted. The mechanism proposed by
Diaz is the one most commonly referred to in the literature although
several other mechanisms are not lacking in support. The controversy lies
in the initiation step as each mechanism proposes a different way of
beginning the reaction, varying between electron transfer, proton transfer
and direct radical pyrrole formation. Without considering the initiation
step, there are many other factors including electrolyte, solvent,
temperature and pH which can influence the reaction mechanism during the
electropolymerization of pyrrole, thus impacting the characteristics of the
polymer formed at the electrode.

The mechanisms of pyrrole electropolymerization

The synthesis, properties and applications of polypyrrole (PPy), a representative of conducting polymers, are reviewed. Chemical and electrochemical methods for the preparation of PPy and PPy films and the effect of the reaction conditions on the properties of the polymer produced are discussed. The mechanisms of electrochemical polymerisation of pyrrole are compared. The physicomechanical properties of the polymer, its morphology and structure are discussed. The mechanism of charge transfer in PPy is considered within the framework of the model of quasi-equilibrium concentrations of polarons and bipolarons. The methods for modification of the electrochemical performance of PPy are reviewed, in particular, synthesis of PPy from pyrrole derivatives with the appropriate electroactive groups and introduction in the PPy of electroactive dopant anions and the effect of those on the electrochemical performance of PPy films are considered. Examples of the use of PPy are given and the prospects for its application in various areas are discussed. The bibliography includes 254 references.

https://iopscience.iop.org/article/10.1070/RC1997v066n05ABEH000261/pdf

Polypyrrole : a conducting polymer; its synthesis, properties and applications

Arylglyoxals in synthesis of heterocyclic compounds.

Pulse polymerized polypyrrole electrodes for high energy density electrochemical supercapacitor

The role of the counter-ion in the preparation of polypyrrole films with enhanced properties using a pulsed electrochemical potential

Structure property relationships in electrically conducting copolymers formed from pyrrole and N-methyl pyrrole

The inherent possibility of structural anisotropy in polypyrrole and other heterocyclic systems is introduced. By selecting the appropriate electrochemical variables including monomer and dopant type this intrinsic molecular anisotropy may be used to prepare films with well defined global anisotropy, in which the planes of the pyrrole rings prefer to lie parallel to the electrode surface. The conditions for obtaining such materials are discussed and some of the effects of these novel anisotropic structures on the resultant properties are highlighted. Attention is directed at charge transport and optical properties.

M.S. Kiani

Papers

The role of the counter-ion in the preparation of polypyrrole films with enhanced properties using a pulsed electrochemical potential

Structure property relationships in electrically conducting copolymers formed from pyrrole and N-methyl pyrrole

Influence of synthesis on the structure of electrochemically prepared electrically conducting polymers

Highly anisotropic electrically conducting films based on polypyrrole

Muon studies of conducting polymers