Biology Reference
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However, this method was successfully used for the preparation of
the film of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with
poly(styrene sulfonic acid) (PSS) at the surface of ITO electrodes
[6] and for the preparation of immunosensors based on conjugated
poly(phenylenevinylene) derivatives of defined thickness [7].
10.2.3
Electropolymerization
Another method often used for the preparation of conducting
polymers, such as polypyrrole (Ppy), polyaniline (PANI), polythio-
phene, and their derivatives is deposition by electropolymerization
in the electrolyte-containing monomers. This method can be used
for the polymerization of compounds which possess a relatively
low anodic oxidation potential and are susceptible to electrophilic
substitution reaction. The electropolymerization is reported as a
simple as well as reproducible method, where the monomer is
first oxidized to a cation radical. Next, the molecule of monomer
is attached to form a dication. Repeated process lengthens out the
polymeric chain and the final polymer is formed. The advantage of
this method is that the rate of film deposition can be controlled by
varying the potential of the working electrode in the system. It is
a simple and reproducible method [8]. Electropolymerization can
be provided potentiostatically, galvanostatically, or by the potential
cycling method. In general, the potentiostatic method is used to
prepare thin films, while the galvanostatic method enables to
prepare thick films [9].
The properties of the polymeric films can be easily modified
by functionalization of the polymer. Two methods are reported for
these purposes:
(i) The functional groups are attached to the monomers through
covalent bonds and then electropolymerization is provided
[10]. The disadvantages of this method are loss of polymer
conductivity, steric hindrance, and cross-linkingeffects.
(ii) Another often used method is incorporation of a dopant into
the polymeric network electrostatically during the process of
electropolymerization [11].
