ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 9, pp. 1500−1504. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © E.K. Fomina, L.P. Krul’, E.V. Grinyuk, 2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 9, pp. 1359−1363.
AND POLYMERIC MATERIALS
Phase State of Aqueous Solutions
of Acrylamide–Sodium Acrylate Copolymers
in the Presence of Copper, Zinc, and Manganese Ions
E. K. Fomina
, L. P. Krul’
, and E. V. Grinyuk
Research Institute of Physicochemical Problems, Leningradskaya ul. 14, Minsk, 220050 Belarus
Belarussian State University, Leningradskaya ul. 14, Minsk, 220050 Belarus
Received May 25, 2015
Abstract—Introduction of copper(II), zinc(II), and manganese(II) ions into aqueous solutions of acrylamide–
sodium acrylate copolymer leads to phase separation. The position of the boundary between the liquid phase
and the precipitate is determined by the copolymer composition, its concentration in solution, and nature and
concentration of the ion being introduced.
Water-soluble polymers, in particular, copolymers of
acrylamide (AAm) with sodium acrylate (ANa), exhibit
high adhesion, ﬁ lm-forming, and water-retaining power.
They are widely used in agricultural practice as a compo-
nent of aqueous protective and stimulating formulations
(PSFs) containing chemical or microbiological plant
protection agents, growth regulators, and macro- (N, P, K)
and microelements (Cu, Zn, Mn, Co, Mo, Fe, etc.) [1, 2].
Most frequently, micro- and macroelements are used in
the form of salts dissociating in water. It is well known
that the presence of metal ions can lead to phase sepa-
ration of aqueous solutions of AAm–АNa copolymers
[3, 4]. Such separation is undesirable, as it complicates
or makes impossible at all the commercial use of PSFs
for treatment of seeds or vegetating crops, because the
insoluble compounds formed in the aqueous medium plug
the nozzles through which the plants are being sprayed
with the solution.
The phase state of aqueous solutions of AAm–
АNa copolymers depends not only on the nature
and concentration of microelement ions, which are
subject to regulations based on experimental data on
their agrochemical activity, but also on the number of
other factors (chemical composition of the copolymer,
parameters of its molecular structure, concentration in
solutions, pH of solution) [3, 4], which can be varied in
the course of PSF preparation.
However, the effect of microelement ion additions
on the phase state of aqueous solutions of AAm–АNa
copolymers was not studied systematically.
This study was aimed at determining how the com-
position and concentration of the ААm–АNa copolymer
and the concentrations of microelement ions inﬂ uence the
phase state of the system consisting of water, ААm–АNa
copolymer, and М(II) acetate, where М is Cu, Zn, or Mn.
AAm–ANa copolymers of different compositions
were synthesized in aqueous solutions in the presence
of the redox initiating system ammonium persulfate
(APS)–sodium sulﬁ te (SS) by the known procedure .
As starting monomers we used acrylic acid pre-
liminarily puriﬁ ed by vacuum distillation and AAm.
Acrylic acid was neutralized with a 10% aqueous NaOH
solution. All the chemicals used were of chemically
pure grade. The initiating system was a mixture of 10%
aqueous solutions of APS and SS. The concentration of
the monomers in aqueous solution was also 10 wt %.
APS was taken in an amount of 0.5 wt % relative to the