Kinetics of Radical Polymerization of a Monomer Derived from Monoethanolamine Vinyl Ether and 1,4-Benzoquinone: A Polarographic Study

Article abstract of DOI:10.1023/A:1025621305767

Radical polymerization of a disubstituted monomer derived from monoethanolamine vinyl ether and 1,4-benzoquinone was studied by classical polarography. The optimal conditions for the synthesis of the redox polymer were found. The polymerization rate const

Full text of DOI:10.1023/A:1025621305767

Russian Journal of Applied Chemistry, Vol. 76, No. 3, 2003, pp. 460 463. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 3,
2003, pp. 475 478.
Original Russian Text Copyright
2003 by Ergozhin, Mukhitdinova, Shoinbekova, Nikitina, Nuranbaeva.
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
Kinetics of Radical Polymerization of a Monomer
Derived from Monoethanolamine Vinyl Ether
and 1,4-Benzoquinone: A Polarographic Study
E. E. Ergozhin, B. A. Mukhitdinova, S. A. Shoinbekova,
A. I. Nikitina, and B. M. Nuranbaeva
Bekturov Institute of Chemical Sciences, Ministry of Education and Science of the Kazakhstan Republic,
Almaty, Kazakhstan
Received February 27, 2002
Abstract Radical polymerization of a disubstituted monomer derived from monoethanolamine vinyl ether
and 1,4-benzoquinone was studied by classical polarography. The optimal conditions for the synthesis of the
redox polymer were found. The polymerization rate constants, preexponential term in the Arrhenius equation,
and activation energy were calculated.
The versatility of redox and ion-exchange poly-
mers, on the one hand, and the limited range of mono-
mers suitable for their synthesis, on the other hand,
require more intense studies in this field, with the aim
to develop novel sorption processes [1, 2]. The prob-
lem of preparing new redox monomers from cheap
and readily available precursors remains very urgent,
since the available redox resins do not always meet
the existing requirements. Among promising precur-
sors are quinones, which widely occur in the nature
and are fairly comprehensively studied. Previously
[1 5] we described redox polymers based on various
quinones and prepared by chemical modification of
polystyrene and styrene diene copolymers with qui-
nones, di- and trihydroxybenzenes, and their halo
derivatives.
unsaturated monomers is the polymerization rate con-
stant. However, only in a few papers [12 14] this
quantity was determined polarographically. The rela-
tionship between the rate constants of radical poly-
merization of monomers and the potentials of the half-
waves of their reduction on a mercury dropping elec-
trode were established in [13].
In this work we studied by classical polarography
the kinetics of radical polymerization of a disubsti-
tuted monomer derived from MEAVE and 1,4-benzo-
quinone (MEAVE 1,4-BQ), calculated the polymeri-
zation rate constants at various temperatures, the acti-
vation energy, and the preexponential term in the
Arrhenius equation.
EXPERIMENTAL
With the aim to extend the assortment of redox
resins and simplify their preparation, we developed a
procedure for single-stage synthesis of new unsatu-
rated monomers [6] from readily available and cheap
monoethanolamine vinyl ether (MEAVE) and various
quinones. This reduced the cost of redox ion exchang-
ers and made their production profitable; the capabil-
ity for reversible oxidation reduction allows repeated
use of these resins, which is important for commercial
applications.
Monoethanolamine vinyl ether was dried over
freshly distilled K CO and distilled from calcium
2
3
20
hydride; bp 114 C, n 1.4382.
D
1,4-Benzoquinone (pure grade) was recrystallized
from methanol; mp 116 C after purification.
Azobis(isobutyronitrile) (AIBN) was recrystallized
from absolute methanol; mp 102 103 C.
The monomer, 2,5-bis[N-(2-vinyloxy)ethyl]amino-
One of reliable, highly sensitive, and quick meth-
ods for analysis of macromolecular compounds is
polarography. It is widely used in kinetic studies of
polymerization of vinyl monomers [7 12]. It is known
that the principal characteristic of the reactivity of
1,4-benzoquinone C H N O , was prepared as fol-
14 18
2 4
lows. MEAVE was added in 6 : 1 ratio to a solution
1
of 1,4-BQ in 1,4-dioxane (28.2 g l , or 0.26 M) at
25 C with continuous stirring. After 15 min, distilled
1070-4272/03/7603-0460$25.00 2003 MAIK Nauka/Interperiodica

KINETICS OF RADICAL POLYMERIZATION
461
Table 1. Elemental composition and some physicochemical properties of the monomer derived from MEAVE and 1,4-BQ
and of its polymer
Calculated, %/Found, %
SEC** ROC***
Com-
pound
Yield,
%
[ ],*
dl g
,**
g cm
Tm, C
1
3
1
C
H
N
O
mg-equiv g
Monomer 60.43/60.47 6.47/6.58 10.07/11.08 23.03/12.87 62.36 172 175
Polymer 60.43/60.49 6.47/6.49 10.07/11.00 23.03/22.02 67.80 216 218
0.4442
1.0714
0.43
8.7
4.2
* The intrinsic viscosity was determined at 25 C in DMF.
** The density and static exchange capacity were determined according to [15].
*** The redox capacity was determined according to [1].
water was added, the precipitate was filtered off, re-
precipitated, and dried first in air and then in a vacu-
um oven at 40 50 C to constant weight. The chemi-
cal composition and some physicochemical properties
of the MEAVE 1,4-BQ are listed in Table 1.
urements, the solutions were purged with argon to
remove oxygen. The half-wave potentials were deter-
mined by graphic solution of the wave equation in the
coordinates logi/(I i) vs. E, where i is the current
at voltage E and I is the diffusion current [16, 17].
Experiments on studying the kinetics of radical
polymerization of the new disubstituted redox mono-
mer based on MEAVE and 1,4-BQ, 2,5-bis[N-(2-vin-
yloxy)ethyl]amino-1,4-benzoquinone (MEAVE 1,4-
BQ), were performed as described above; after a cer-
tain time, the ampules were successively opened, and
samples were taken for polarographic analysis. The
samples were diluted with DMF to stop the reaction.
Polarographic measurements were performed in 25%
DMF, with phosphate buffer solution (pH 7.4) as sup-
porting electrolyte. The conversion was judged from
the amount of the unchanged monomer. Experiments
revealed a linear relationship between the heights of
the polarographic waves and the monomer concentra-
tion in the solution. The monomer content was deter-
mined from the calibration plot.
Polymerization of MEAVE 1,4-BQ was performed
as follows. AIBN, 1 7 wt % relative to the monomer,
was added into an ampule containing a solution of the
1
monomer in dimethylformamide (DMF; 0 44 g l ).
The ampule was purged with argon, sealed, thorough-
ly shaken, and placed in a thermostat heated to 55
75 C. After reaction completion, the ampule was
quickly transferred in a beaker filled with ice, cooled,
and opened. The precipitate was filtered off and dried
first in air at 20 25 C and then in a vacuum oven at
40 50 C. The polymer yield was 50.0 67.8%. The
optimal conditions are as follows: monomer concen-
1
tration in DMF 25 g l (0.0899 M); AIBN amount
1
5 wt % relative to the monomer (1.25 g l , or 0.762
2
10 M); 68 C; 120 min. The main physicochemical
characteristics of the polymer are given in Table 1.
Analysis of the reaction mixture furnished informa-
tion on the degree of conversion and allowed con-
struction of the polymerization curves (Fig. 1).
The IR spectra of the new quinoid derivative of
MEAVE contains the following absorption bands,
cm : NH stretching 3256; NH bending 1552; C=O
1
stretching 1660; C=C stretching 1568, 1440; =C N
stretching 1328; and C O C stretching 1200. The
absorption band of quinoid rings in the spectrum of
the polymer becomes broader, which is typical of
polymeric quinones, and these bands are shifted to-
To calculate the overall polymerization rate con-
stants, we determined the reaction order. The log-
arithmic dependence of the polymerization rate on the
initiator concentration (Fig. 2) and the linear depen-
1
ward higher frequencies to 1680 cm . The bands at
A, %
1
about 3040 cm characteristic of the vinyl group
1
disappear, whereas the bands at 2936 and 1496 cm
belonging to the CH groups grow in intensity.
2
The polarograms were taken in a temperature-
controlled cell at 25 0.5 C with a PU-1 polarograph
equipped with a mercury dropping electrode having
, min
2/3 1/6
the open-curcuit capillary characteristic m
t
=
Fig. 1. Kinetic curves of MEAVE 1,4-BQ polymerization:
(A) polymer yield and ( ) time. Temperature, C: (1) 68,
(2) 75, (3) 62, and (4) 55.
2/3 1/2
4.38 mg
s
. As reference electrode was used satu-
rated calomel electrode. Prior to polarographic meas-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 76 No. 3 2003

462
ERGOZHIN et al.
In the chosen scale, tan = tan32 = 0.6249,
1
logV [mol l 1 min ]
=
3
10 , and activation energy E = 4.571 0.6249 =
1
1
2.86 kcal mol (11.95 kJ mol ).
The synthesized disubstituted monomer derived
from MEAVE and 1,4-BQ readily polymerizes, in
contrast to the starting MEAVE, which, as reported
in [20, 21], does not form homopolymers in the pres-
ence of radical initiators. Apparently, this is due to the
reactivity of the radical, which is the decisive factor
in homopolymerization. The higher the electron den-
sity localized on the double bond, the more reactive is
the monomer [7, 10]. The polarographic parameters
are also determined by the electron density localized
on the double bond: the higher the electron density,
the more negative is the half-wave potential of the
reduction of the double bond, i.e., the more negative
the potential, the readier is the polymerization, which
is indeed the case with MEAVE 1,4-BQ.
log [In] [wt %]
Fig. 2. Logarithmic plot of the polymerization rate, logV,
vs. initiator concentration log[In].
logcmon [M]
, min
Fig. 3. Plot of logc
vs. time of MEAVE 1,4-BQ poly-
mon
merization.
CONCLUSIONS
1
103/T, K
1
ln k [s ]
(1) Radical polymerization of the new disubsti-
tuted derivative based on monoethanolamine vinyl
ether and 1,4-benzoquinone was studied, and optimal
conditions were found for formation of the polymeric
redox resin.
Fig. 4. Logarithm of the rate constant lnk of MEAVE
1,4-BQ polymerization as a function of temperature T.
(2) The kinetics of radical homopolymerization
was studied, and the rate constants, activation energy,
and preexponential term in the Arrhenius equation
were calculated.
dence of logc of the monomer on the reaction time
(Fig. 3) show that the reaction is first-order with re-
spect to the initiator (n = 0.80) and monomer (m =
0.86) and is described by relationships characteristic
of first-order reactions.
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, where is the slope of the
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