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Section 12. Chemistry
Tadjieva Shakhnoza Abduvalievna, Basic doctoral student, Tashkent chemical-technological institute Maksumova Oytura Sitdikovna, Professor, Doctor of Chemical Sciences Tashkent chemical-technological institute E-mail: omaksumovas@mail.ru Ergasheva Dilfuza Amilovna, Associate Professor, Candidate of Technical Sciences, Tashkent chemical-technological institute
COPOLYMERIZATION OF ISOHEXYLACRYLATE WITH STYRENE
Abstract. The copolymerization of isohexyl acrylate with styrene in the presence of a radical initiator in an environment of organic solvents has been studied. It has been determined that in all cases the copolymers are enriched in isohexyl acrylate units. The application as a comonomer leads to an increase in the reaction rate and the yield of the copolymer at last.
Keywords: copolymerization, isohexylacrylate, styrene, initiator, comonomer.
Introduction ity of functional monomers and find approaches to
The synthesis of polyfunctional polymers has at- clearing the features of radical processes that occur
tracted many researchers, and this interest is growing with the participation of various functional groups
steadily. This is due to a wide range of useful prop- in the formation of the polymer chain. Most often,
erties of these polymers, which have established vinyl and acrylic monomers containing carbonyl and
themselves as promising flocculants, sorbents, car- amino groups in the structure have been used to ob-
riers of physiologically active agents, separation tain such polymers [2, P. 140; 3, P. 199]. membranes, etc. [1, P. 188]. Success in this area of The results of the initiated radical copolymeriza-
high molecular compounds is determined, first of tion of methyl methacrylate with methacrylic acid
all, by the development of effective methods for the in a medium of solvents with different polarity: ac-
synthesis of polyfunctional polymers based on avail- etone, toluene and methanol are presented in the
able raw materials. One of the promising methods work [4, P. 140]. It is shown that the activation en-
for obtaining polymers with a complex of desired ergy increases in the presence of acetone and metha-
properties is radical copolymerization. The study of nol while it decreases in toluene. such reactions is not only of practical value, but also However, information on the copolymerization
important from a theoretical point of view, because of isohexyl acrylate is not available in the literature. In
it allows to evaluate the comparative reactive activ- connection with the above, the search, development
of new approaches and effective methods for the synthesis of new copolymers based on unsaturated ester - isohexyl acrylate with vinyl monomers is an urgent task.
The aim of this work is the synthesis of unsaturated ester based on 2-methyl- 1-pentene with acrylic acid and its copolymers with styrene.
Experimental part
Acrylic acid, 2-methyl-1-pentene, DMF, ethyl alcohol were distilled before use, and drying was carried out through standard methods. The initiators - dinitrile azobisisobutyric acid (DAC), benzoyl peroxide (PB) have been recrystallized from a solution in absolute ethanol, dried in a vacuum desiccator to constant weight.
The studies have been carried out through the gravimetric method [4, P. 304]. This method is based on the separation of the polymer from the reaction medium by precipitation of it in solvents that dissolve the monomer and do not dissolve the polymer. The polymer is released as a precipitate, which is washed with a precipitant and then it is dried to constant weight and weighed on an analytical balance. The reaction rate has been determined by the degree of conversion of the monomer to a given point in time,.
The copolymerization has been carried out in glass ground tubes. The required amount of initiator was placed in clean tubes with ground stoppers and the solvent, an ester based on 2-ethyl-1-pentene with acrylic acid, styrene in the required proportions, was poured. The mixture was stirred until the initiator was dissolved, then the tubes were purged with nitrogen for 10 minutes, carefully closed with glass stoppers and placed in a thermostat with a temperature of 60-80 °C. The copolymerization reaction was carried out to small degrees of conversion, which was determined by reaching a syrupy mass. It has been determined that in different ampoules the copolymerization rate is different - the reaction rate increases with increasing ester content in the mixture of comonomers. At the end of the copolymerization, the ampoules were cooled to room temperature and
the stoppers were opened, the contents were slowly poured with stirring into a glass with a precipitant (acetone, alcohol). Samples of the copolymers were cool- dehumidified and weighed to constant weight on an analytical balance with an accuracy of ±0.0002. The resulting copolymers are white powdery products that dissolve in benzene, toluene and dimethyl-formamide.
The IR-spectra of the ester and the synthesized copolymers have been recorded on a SISTEM-200 FT-IR spectrophotometer.
Results and discussions
The method of esterification of acrylic acid with liquid olefins is a convenient method for the synthesis of esters. Synthesis of an ester based on 2-meth-yl-1-pentene with acrylic acid has been carried out according to the procedure described in [5, P. 260]. The structure of the obtained ether was confirmed by the IR-spectral method (Fig. 1).
In the IR-spectrum of an ester based on 2-meth-yl- 1-pentene with acrylic acid, new absorption bands of stretching vibrations of the C-O-C bond in the region of 1297 cm-1 were found, stretching vibrations of the carbonyl group having a double bond in the region of 1704 cm-1, absorption bands of the -CH3, -CH2 groups at 2583-2934 cm-1, and there is no wide spectrum of carboxyl groups in the region of 3600 cm-1. The absorption bands at 1636 cm-1 correspond to the -C=C- bond stretching vibrations; the ether band C-C (=O)-O and O-C-C - consisting of two interacting antisymmetric vibrations are observed in the range 1045-1297cm- 1 (see fig. 1).
The copolymerization of ester of 2-ethyl-1-pen-tene and acrylic acid (M1) with styrene (M2) has been carried out in the low-conversion region at a temperature of 60-80 °C in the presence of a radical initiator of benzoyl peroxide (BP) in an organic solvent. Dimethylformamide was used as a solvent.
To determine the effect of the composition of the initial mixture ofmonomers on the composition of the resulting copolymers, the reaction has been carried out at various molar ratios of comonomers (Table 1).
cm-1
Figure 1. IR-spectrum of an ester based on 2-ethyl-1-pentene with acrylic acid
Table 1. - Copolymerization of M1 with M2 in a DMF solution (BP = 5 • 10-3 mol/l, 60 °C, 3 hours)
Composition of initial mixture,% mole Yield,% Composition of copolymer,% mole
М, М2 m, m2
10 9o 2.5 11.2 88.8
3o 7o 3.7 33.6 66.4
so so s.o 55.6 44.4
7o 3o 6.1 78.o 22.o
9o 1o 8.4 97.8 2.2
The results show that the ester is a more active monomer compared to styrene.
It should be noted that the copolymerization of the ester with styrene is completely inhibited in the presence ofhydroquinone and atmospheric oxygen, which confirms the radical nature of the process mechanism.
The structure of the obtained copolymers has been determined by IR-spectroscopy. The IR-spec-tra of the copolymers have been analyzed and com-
pared with the spectra of the starting monomers and their homopolymers obtained under similar conditions. In the IR-spectra of the copolymers, absorption bands characteristic of the double bond of monomers in the regions of 1636-1640 cm-1 are absent, which confirms the course of the reaction along the vinyl groups of the starting monomers. The stretching vibrations of the C - O and C=0 groups are in the region of 1155 cm-1 and 1681-1716 cm-1.
The solubility and other properties of the co- solve in dimethylformamide, dimethyl sulfoxide,
polymers depend both on the ratio of comonomer benzene, toluene.
units in the copolymer chain and on the nature of Thus, an unsaturated ester based on 2-eth-
the second comonomer, styrene. The synthesized yl-1-pentene and acrylic acid has been synthesized
copolymers based on M1 with M2, at all ratios of and copolymerized with styrene in dimethylfor-
monomer units in the macromolecule, well dis- mamide in the presence of benzoyl peroxide at a
temperature of 60 °C.
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3. Batig S. M., Melnichenko V. I. Kinetic parameters of the copolymerization of methyl methacrylate with methacrylic acid in the presence of solvents of different polarity // News of the Donetsk National University. Ser. A: Natural sciences. 2014.- No. 1.- P. 140-143.
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