ISSN 0012ꢀ5008, Doklady Chemistry, 2010, Vol. 432, Part 1, pp. 121–125. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.M. Lopatin, S.S. Bukalov, L.A. Leites, Yu.V. Korshak, L.N. Nikitin, A.R. Khokhlov, 2010, published in Doklady Akademii Nauk, 2010, Vol. 432, No. 1,
pp. 55–59.
CHEMISTRY
Synthesis of Polyaniline
in Supercritical Carbon Dioxide
A. M. Lopatina, S. S. Bukalova, L. A. Leitesa, Yu. V. Korshakb,
L. N. Nikitina, and Academician A. R. Khokhlova
Received December 11, 2009
DOI: 10.1134/S0012500810050010
Supercritical carbon dioxide (scꢀCO2)—an enviꢀ cell through a system of valves. The desired temperaꢀ
ture is maintained by means of a thermostat in which
the autoclave is placed. Carbon dioxide with a purity
of 99.995% (State Standard GOST 8050ꢀ85) was used
in the synthesis of PANI.
ronmentally acceptable, inexpensive, nontoxic, and
nonflammable medium—is widely used as a solvent in
synthesis and modification of polymers based on variꢀ
ous monomers [1, 2]. As a rule, an advantage of using
scꢀCO2 is the absence of side reactions of chain termiꢀ
nation and chain transfer to the solvent [2], which
ensures the preparation of highꢀpurity polymers.
The following regents were used as purchased:
aniline (99.8%, Aldrich) dodecylbenzenesulfonic acid
(DBSA, Aldrich) with an admixture of isomers C10–
C13, ammonium persulfate (98%, Aldrich), and
anhydrous ethanol (96%, Khimmed, Russia).
In recent years, attention has been focused on the
possibility of using scꢀCO2 in polycondensation proꢀ
cesses [3, 4]. Of special interest is the synthesis and modꢀ
ification of conducting polymers polypyrrole [5], polyaꢀ
niline (PANI) [6], etc., as well as design of hybrid mateꢀ
rials based on these polymers, in an scꢀCO2 medium.
The oxidative polymerization of aniline in scꢀCO2
was carried out in several stages.
At the first stage, the salt of DBSA and aniline was
synthesized by the direct reaction of two reagents in a
liquid phase at room temperature. The reaction began
as soon as two liquids taken in an equimolar ratio—
DBSA (6.53 g, 20 mmol) and aniline (1.86 g,
20 mmol)—contacted each other when mixed in the
reactor. The mixture grew turbid within 1–2 s and then
solidified within 30–40 s to form a white mass (8.31 g,
99%) of anilinium dodecybenzenesulfonate. This salt
turned out to be soluble in a supercritical medium.
Elemental analysis showed that the product was of
high purity.
Traditional methods of production of PANI involve
the oxidative polymerization of the monomer with the
use of ammonium persulfate (NH4)2S2O8 as the oxiꢀ
dant or electrochemical synthesis, which is currently
more popular since it offers significant advantages over
the chemical synthesis [7].
In the present work, we developed for the first time
the method of synthesis of PANI through oxidative
polymerization of aniline in scꢀCO2 and characterized
the products by spectroscopy.
For C24H37S1N1O3 anal. calcd. (%): C, 69.13;
H, 9.00; N, 3.45; S, 7.57. Found (%): C, 69.31; H,
9.04; N, 3.27; S, 7.46.
The setup for synthesis by means of scꢀCO2 is
shown in Fig. 1. It is equipped with a generator creatꢀ
ing a pressure of up to 35 MPa, which is connected
through a system of capillaries with a stainless steel
autoclave with a working volume of 30 mL. The setup
is equipped with pressure gauges for controlling the
scꢀCO2 parameters. Carbon dioxide CO2 is fed to the
At the second stage, anilinium dodecybenzeneꢀ
sulfonate and ammonium persulfate taken in a 1 :
1.25 molar ratio (the optimal ratio for the classical
synthesis) were placed onto the bottom of the autoꢀ
clave. The system was thermostated at 70°C, and
CO2 was introduced to a pressure of 35 MPa. The
reaction was carried out for 2 h, and then the autoꢀ
clave was cooled to room temperature. The pressure
was reduced to atmospheric, and the resulting prodꢀ
uct was washed with ethanol and water. Then, PANI
(insoluble black powder) was dried in air to constant
weight. The reaction of formation of PANI is shown
in Scheme 1.
a Nesmeyanov Institute of Organoelement Chemistry,
Russian Academy of Sciences, ul. Vavilova 28, Moscow,
119991 Russia
b Mendeleev Russian University of Chemistry
and Technology, Miusskaya pl. 9,
Moscow, 125047 Russia
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