Organic Electrode Reactions - Fundamentals and Applications of Organic Electrochemistry - page 170

polymerization is useful for application in
electrochemical devices such as sensors and
displays [90]. This chapter deals with
electro-oxidative polymerization,
electro-reductive polymerization and
electrosynthesis of polysilane. Polymerization
of vinyl monomers using an electrogenerated
initiator system is summarized elsewhere [91],
although recent developments in this process
are included in this chapter.
5.8.1 Electro-oxidative Polymerization of
Aromatic Monomers
The electron-rich aromatic and hetero-aromatic
monomers listed in Figure 5.18 can be easily
oxidized on the anode surface to form their
radical cation states. The radical cations couple
to form C-C bonds, and following
deprotonation this leads to a neutral dimer ( Eq.
5.36 ). The generated conjugated dimer has a
lower oxidation potential than that of the
monomer, so further oxidation of the dimer
leads to oligomerization and polymerization.
The highly conjugated polymers are no longer
soluble in electrolytic medium and therefore are
deposited on the anode surface as a film. The
deposited polymer is oxidatively doped during
the application of potential for polymerization,
thus the film formed is not passive but still
conductive to carry out a continuous
electrochemical reaction on the electrode. In
this procedure, the coupling position of