Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 4, pp. 728−731.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
E.V. Sivtsov, O.G. Yasnogorodskaya, E.V. Chernikova, A.P. Voznyakovskii, 2010, published in Zhurnal Prikladnoi Khimii, 2010,
Vol. 83, No. 4, pp. 676−679.
AND POLYMERIC MATERIALS
Determination of the Molecular-Weight Characteristics
of Polyacrylic Acid and Its Copolymer
with Butyl Acrylate
E. V. Sivtsov
, O. G. Yasnogorodskaya
, E. V. Chernikova
and A. P. Voznyakovskii
St. Petersburg State Institute of Technology, St. Petersburg, Russia
Lomonosov Moscow State University, Moscow, Russia
Lebedev Research Institute of Synthetic Rubber, St. Petersburg, Russia
Received June 8, 2009
Abstract—A new procedure was suggested for pretreatment of polyacrylic acid and its copolymer with butyl
acrylate with the aim of examining the molecular-weight distribution: chemical modiﬁ cation by esteriﬁ cation
with benzyl alcohol. Conditions were chosen for turbidimetric titration of the resulting polymers. The results
conﬁ rmed the efﬁ ciency of isopropanol as chain-transfer agent in copolymerization of acrylic acid with butyl
acrylate. The molecular-weight characteristics of polyacrylic acid prepared by radical polymerization in water in
the presence of Cu(II) ions were determined.
Polymeric surfactants play an important role in
science and engineering. Their behavior and mechanism
of the action largely differ from those of the low-
molecular-weight analogs, but basic studies in this
ﬁ eld are considerably fewer than it should be expected.
Compounds containing carboxy groups, responsible
for their diphilic nature, form an important group of
polymeric surfactants. The simplest representatives of
this group are polyacrylic acid (PAA) and its copolymers
with hydrophobic monomers, e.g., butyl acrylate (BA).
It is interesting that PAA can behave quite differently
depending on the molecular weight (MW). Relatively
low-molecular-weight PAA (MW up to several
thousands) is a good dispersant. It stabilizes suspensions
and prevents scale deposition [1, 2]. High-molecular-
weight PAA, on the contrary, favors coagulation of the
dispersed phase and is an effective ﬂ occulant .
Control of the molecular-weight characteristics of
PAA and development of reliable procedures for their
determination is a topical problem.
The AA–BA copolymer containing 5 mol % BA units
was prepared by radical polymerization of a mixture of
the monomers in water and in isopropanol under the
In water, the concentration of the monomers (M) was
as follows: AA 1.2 and BA 6.3 × 10
; as initiator we used
ammonium persulfate (AP) (4 × 10
M). The synthesis
was performed at 85°C up to complete exhaustion of the
monomers, with additional introduction of water so as to
avoid gel formation and obtain a 5% aqueous solution of
the polymer by the end of the synthesis.
In isopropanol, we prepared an AA–BA copolymer of
lower MW than in water, using the well-known property
of isopropanol as an effective chain-transfer agent in
radical chain reactions. The synthesis was performed
with azobis(isobutyronitrile) (AIBN) as initiator at 70–
75°C. The component concentrations were as follows,
M: AA 1.02, BA 5 × 10
, and AIBN 4.8 × 10
complete exhaustion of the monomers, we obtained
a 10% solution of the polymer in isopropanol.
It is known [3, 4] that AA polymers of relatively
low MW can be obtained in the presence of Cu