Copolymerization of 2-chloro-substituted p-cyclopropylstyrenes with styrene and properties of the resulting copolymers

Article abstract of DOI:10.1007/s11167-005-0281-4

2,2-Dichloro- and 2-chloro-1-(p-vinylphenyl)cyclopropanes were prepared and brought into copolymerization with styrene. The effect of substituents on the reactivity of the monomers was examined. The physicomechanical properties of the copolymers were stud

Full text of DOI:10.1007/s11167-005-0281-4

Russian Journal of Applied Chemistry, Vol. 78, No. 2, 2005, pp. 311 314. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005,
pp. 316 319.
Original Russian Text Copyright
2005 by K. Guliev, Ponomareva, A. Guliev.
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
Copolymerization of 2-Chloro-Substituted p-Cyclopropylstyrenes
with Styrene and Properties of the Resulting Copolymers
K. G. Guliev, G. Z. Ponomareva, and A. M. Guliev
Institute of Polymeric Materials, National Academy of Sciences of Azerbaijan, Sumgait, Azerbaijan
Received July 14, 2004
Abstract 2,2-Dichloro- and 2-chloro-1-(p-vinylphenyl)cyclopropanes were prepared and brought into co-
polymerization with styrene. The effect of substituents on the reactivity of the monomers was examined.
The physicomechanical properties of the copolymers were studied.
One of the ways to improve the physicomechani-
cal, thermal, and optical properties and enhance the
flame resistance of polystyrene plastics is copolymer-
ization of styrene with other monomers. In so doing,
it is possible to vary the properties of the copolymers
in a wide range.
tions of the benzene ring. Strong bands at 1213 and
1
1
1170 cm and bands at 1110 and 1013 cm are
characteristic of 1,4-disubstituted benzenes and belong
to the in-plane bending modes of the four hydrogen
atoms of the benzene ring.
Changes in the intensities of the bands belonging
to the main functional groups of I and II suggest
changes in the composition of the monomeric units.
The copolymerization of styrene with substituted
styrenes has been studied extensively [1 7].
In this study, we prepared 2,2-dichloro- and 2-chlo-
ro-1-(p-vinylphenyl)cyclopropanes (I, II, respectively)
and performed their copolymerization with styrene in
the bulk and in solution; we also examined the effect
of the chlorinated substituents on the reactivity of the
monomers and on the properties of the resulting co-
polymers. We found that styrene smoothly copolymer-
izes with the monomers synthesized, without opening
of the cyclopropane ring; the resulting copolymers are
soluble.
The IR data allow us to ascribe the following struc-
ture to the copolymers:
(
(
)
CH2
CH
)
CH2
CH
n
m
X
where X = 2Cl (I), Cl (II).
For this pair of monomers, we calculated the co-
polymerization constants and the Alfrey Price param-
eeters Q and e [8]. To evaluate the distribution of
units in the macromolecular chain, we calculated the
microstructural parameters LM , LM , and R [9]. The
The copolymerization under the conditions of our
experiments occurred through opening of the double
bond, yielding macromolecules with pendant phenyl
groups (unsubstituted and those bearing chlorinated
cyclopropane fragments). This is suggested by the
spectra of the copolymers. The ratio of the monomeric
units (I or II to styrene) in the copolymer was esti-
mated from the chlorine content determined by ele-
mental analysis.
1
2
results are listed in Table 1.
Table 1 shows that, at any ratio of the starting
monomers, the copolymer is always enriched in units
of mono- or gem-dichloro-substituted cyclopropyl-
styrenes, which is due to the higher reactivity of these
monomers, caused by the presence of the substituted
cyclopropane ring.
The IR spectra of both the starting monomers and
copolymers thereof contain characteristic bands be-
1
longing to vibrations of the C Cl bond (675 cm )
1
and cyclopropane ring (1030 1040 cm ). The spectra
The chlorine atoms, which are present in I and II as
substituents in the cyclopropane ring and are separated
from the reaction center by the phenyl ring and a cy-
of the copolymers also contain well-defined bands at
1
1450, 1500, 1585, and 1605 cm belonging to vibra-
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312
GULIEV et al.
Table 1. Copolymerization of 2,2-dichloro- and 2-chlorocyclopropylstyrenes I and II (M1) with styrene (M2)
Starting
Copolymer com-
Parameters of copolymerization of I and II
Microstructure*
mixture, mol % position, mol %
(M1) with styrene (M2)
M1
M2
M1
M2
LM
LM
R
r1
r2
r1r2
Q1
e1
Cl, %
1
2
Cyclopropylstyrene (I)
10
25
50
75
90
90
75
50
25
10
17.10
35.95
59.75
79.87
91.85
82.90
64.05
40.43
20.19
1.134 5.500 30.15
1.403 2.500 51.24
2.210 1.500 53.91 1.21 0.06 0.50 0.03 0.605 3.523
4.630 1.167 34.50
5.70
11.98
1.508 19.86
26.62
8.15 11.890 1.056 15.45
Cyclopropylstyrene (II)
5.68 29.37
30.62
10
25
50
75
90
90
75
50
25
10
16.66
35.07
59.13
79.68
91.77
83.34
64.93
40.87
20.32
1.13
1.4
2.2
4.6
3.31
6.98
1.486 11.76
15.85
2.56
1.52
1.17
1.06
50.5
53.76 1.20 0.04 0.52 0.02 0.624 2.77
34.66
16.98
7.96 10.72
18.25
*
(L , L ) Mean lengths of blocks of the corresponding monomeric units; (R) harwood parameter of block structure.
M1
M2
clopropane fragment in the p-position relative to the
styrene double bond, decrease the copolymerization
constants relative to unsubstituted styrene. This is due
to increased conjugation in the monomer molecule as
a result of the effect of the substituents additionally
stabilizing the forming radical. The copolymerization
constants of I and II differ insignificantly.
conjugation in the monomer molecule, but only slight-
ly depends on the number of chlorine atoms. This is
confirmed by the UV spectra of I and II, in which
the absorption maxima are located at 295 and 292 nm,
respectively.
To reveal regular trends in the polymerization and
study the properties of the copolymers, we performed
copolymerization of I and II with styrene in a wide
range of ratios of the starting monomers.
The influence exerted by the chlorine atoms on the
vinyl group through the three-membered carbon ring
and phenyl ring leads to an increase in the extent of
The kinetic curves of initiated copolymerization of
I with styrene at 70 C (see figure) show that, after
37 46% conversion of the monomers is reached, the
copolymerization occurs with autoacceleration. The
effect becomes more pronounced as the content of I
in the mixture is increased. The molecular weight of
the forming polymers appreciably increases at high
conversions.
Experiments on thermal copolymerization at high
temperatures (110 150 C) revealed no appreciable
self-acceleration, and the intrinsic viscosity of the
copolymers remained virtually constant at all the con-
versions. Some properties of the copolymers are given
in Table 2.
Table 2 shows that introduction of chloro-substi-
tuted cyclopropylstyrene units into the polystyrene
chain increases the Vicat softening point and enhances
the optical and physicomechanical properties, com-
pared to styrene homopolymer. Some of the copoly-
mers obtained show self-extinguishing behavior. This
property becomes more pronounced with an increase
in the content of I in the copolymer.
Variation with time of the (1 5) yield A and (6, 7) intrin-
sic viscosity [ ] of 2,2-dichloro-1-(p-vinylphenyl)cyclo-
propane (I) styrene copolymer. 70 C. Content of I in the
starting mixture, %: (1, 7) 100, (2) 90, (3) 80, (4, 6) 70,
and (5) 0.
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COPOLYMERIZATION OF 2-CHLORO-SUBSTITUTED p-CYCLOPROPYLSTYRENES WITH STYRENE 313
Table 2. Physicomechanical characteristics of the copolymers prepared
Copolymers with indicated content of I or II, %
Parameter
Polystyrene
40
60
I
II
I
II
1
Intrinsic viscosity [ ], dl g
Refractive index
1.15
1.5895
103
1.17
1.6010
119
16
1.5905
1.6040
1.6010
Vicat softening point,
C
116
128
126
2
Brinell hardness, kgf cm
14
15
Ultimate tensile strength, MPa
Relative elongation at break, %
39.0
1.7
34.8
1.5
35.0
35.0
1.5
Copolymers with indicated content of I or II, %
70 80 90
Parameter
Polystyrene
I
II
I
II
I
II
1
Intrinsic viscosity [ ], dl g
Refractive index
1.15
1.5895
103
1.13
1.6053
132
24
1.15
1.610
139
1.6038
130
16
1.6080
1.6115
1.6105
Vicat softening point,
Brinell hardness, kgf cm
C
148
136
2
14
27
19
Ultimate tensile strength, MPa
Relative elongation at break, %
39.0
1.7
45.0
1.9
47.0
46.8
1.9
48.7
Thus, the properties of the copolymers derived
from chloro-substituted cyclopropylstyrenes are gov-
erned by the substituent in the monomers, and the
activity of the monomers in the copolymerization
depends on the extent of conjugation of the vinyl
electrons with the substituent p electrons.
The purity of the monomers was checked chroma-
tographically; it was 99.9% in all the cases. The kinet-
ics of the copolymerization of I and II with styrene
was studied in ampules in a nitrogen atmosphere at
various ratios of the starting monomers. To determine
the copolymerization parameters, the reaction was
stopped at 10% conversion. The compositions of
the copolymers were determined by elemental analy-
sis for chlorine, and their molecular weights were es-
timated from the intrinsic viscosity, determined with
an Ubbelohde viscometer at 25 C in benzene. All
the copolymers were reprecipitated from a benzene
solution with methanol. The softening points of the
copolymers were determined by the Vicat method.
The physicomechanical parameters of the copolymers
were determined with film samples prepared by cast-
ing from a benzene solution. The IR spectra were
measured with a Specord M-80 spectrophotometer.
EXPERIMENTAL
The starting monomer, 2,2-dichloro-1-(p-vinyl-
phenyl)cyclopropane I, was prepared as described in
[6]. 2-Chloro-1-(p-vinylphenyl)cyclopropane II was
prepared as follows. Sodium metal (0.1 mol, 2.3 g)
was added in small pieces to a solution of I (0.2 mol,
42.6 g) in benzene, after which methanol was added
dropwise with stirring and cooling on an ice bath.
After the reaction was complete, distilled water was
added, the organic layer was separated, and the aque-
ous layer was extracted with ether. The combined
organic phases were evaporated, and the product was
vacuum-distilled; bp 78 80 C/1 mm Hg. Yield 36%
After appropriate purification and drying, all the
copolymers were white powders soluble in aromatic
and chlorinated hydrocarbons.
(12.85 g); n2D0 = 1.5630, d420 = 1.12, MRDcalc/MRDexp
=
52.388/51.76. Analytical data:
CONCLUSIONS
Found, %: C 73.95, H 6.16, Cl 19.88.
(1) New monomers, 2,2-dichloro- and 2-chloro-
Calculated, %: C 73.58, H 6.05, Cl 19.75.
1-(p-vinylphenyl)cyclopropanes, were prepared, and
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314
GULIEV et al.
their copolymerization with styrene was performed.
These monomers are more reactive than styrene in
polymerization, owing to the presence of a substituted
cyclopropane ring.
Vysokomol. Soedin., Ser. B, 1970, vol. 12, no. 10,
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(2) The copolymerization constants and Alfrey
Price parameters of the cyclopropylstyrenes were
calculated. The chlorine substituents in the cyclo-
propane ring make higher the relative reactivity con-
stants and the specific activity of the monomers.
(3) The physicomechanical properties of the co-
polymers were determined. Introduction of chloro-
substituted cyclopropylstyrene units into the polysty-
rene chain increases the softening point, refractive
index, and hardness of the copolymers.
6. Guliev, K.G., Nazaraliev, Kh.G., and Guliev, A.M.,
Azerb. Khim. Zh., 1999, no. 1, pp. 87 90.
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and Guliev, A.M., Azerb. Khim. Zh., 2002, no. 3,
pp. 45 50.
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9. Zil’berman, E.N., Vysokomol. Soedin., Ser. B, 1979,
1. Bylina, G.S., Burykina, L.K., and Ol’dekop, Yu.A.,
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