Organic Electrosynthesis - Fundamentals and Applications of Organic Electrochemistry - page 264

[85]. On the other hand, methods for
controlling their physical structures have been
relatively limited, but recently many studies
have focused on applying ultrasound to
polymerization processes, particularly
electropolymerization, for this purpose.
Osawa et al. found that the quality of
polythiophene films electropolymerized on an
anode can be enhanced by ultrasound. By
conventional methodology the films become
brittle, but by using ultrasound from a 45-kHz
cleaning bath, flexible and tough films (tensile
modulus 3.2 GPa and strength 90 MPa) can be
obtained [86].
The work of Atobe and co-workers was
probably the first 'modern' study investigating
electropolymerization under sonication in a
complete series of papers at low frequencies.
Starting from electro-organic reactions under
ultrasonic fields [87], polymerization of aniline
was studied both in electrochemical [88] and
chemical routes [89,90] as well as synthesis of
nanoparticle synthesis [91,92].
The behaviour of polypyrrole films
electropolymerized under ultrasonication was
also investigated, and unique properties in the
doping-undoping processes were highlighted.
The authors attributed their results to the
elaboration of highly dense film under
sonication, but also deplored the degradation of
the film due to high cavitation at 20 kHz