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ISSN 2522-1841 (Online) AZERBAIJAN CHEMICAL JOURNAL № 3 2022 63
ISSN 0005-2531 (Print)
UDC 678.744.342:547.9
SYNTHESIS AND STUDY OF COPOLYMERS OF METHYL METHACRYLATE WiTH
OLIGOPROPYLENE MACROMONOMERS
V.M.Dostuyeva
Institute of Polymer Materials, NAS of Azerbaijan
azeri- [email protected]
Received 28.01.2022 Accepted 23.02.2022
The reaction of radical copolymerization of oligopropylene macromonomer (MO with methyl methacrylate (M2) has been carried out, the regularities of the reaction and the properties of the obtained products have been studied. It has been found that the values of the relative activity of these monomers are r1=0.02 and r2=12.2, respectively. The fact that the value of the copolymerization constant of the oligopropylene macromonomer is close to zero indicates that it is not prone to homopolymerization reactions and only undergoes copolymerization reactions. The dependence of some properties of the synthesized copolymer on their composition has been studied and it has been shown that with an increase in the amount of the fragment formed from the oligopropylene macromonomer, the softening temperature and intrinsic viscosity values of the copolymers decrease, and, accordingly, a sharp decrease in the average molecular weight is observed. This is due to the passivity of the oligopropylene macromonomer in copolymerization reactions and the high probability of a chain transfer reaction through the oligopropylene macromonomer.
Keywords: oligopropylene macromonomer, polymethyl methacrylate, copolymerization constants, high impact polymethyl methacrylate.
doi.org/10.32737/0005-2531-2022-3-63-69 Introduction
Polymethyl methacrylate (PMMA) is one of the most widely used polymers. The main quality of PMMA is determined by its high transparency. PMMA is an indispensable polymer material that is widely used in the production of lighting equipment, aviation, mechanical engineering, in the manufacture of medical devices and dentures, as well as transparent stationery, blood transfusion devices in medical technology and resonator elements in laser technology and optical discs in laser video players.
PMMA under normal conditions has such disadvantages as brittleness and low impact strength, which significantly limits its use. The chemical modification of polymethyl methacry-late by copolymerization of methyl methacry-late (MMA) with other monomers has led to the development of a range of high impact polymer materials. To increase the elasticity of the polymer material, MMA undergoes copolymerization reactions with monomers, which can also play the role of a structural plasticizer in copol-ymers [1-5].
In the scientific literature, the use of iso-butylene, butadiene, 1-butene, 3-methyl-1-bu-
tene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 5-methyl-1-hexene, 4-ethyl-hexane, 1-octene, 1-dodecene, n-butyl acrylate, 3-phenylpropene, as well as their mixtures and other alpha-olefins, is proposed as plasticizing comonomers [6-11]. Polymers based on 1-hexene are characterized by low glass transition temperature and high elastic properties. In copolymers based on 1-hexane, it acts as an internal plasticizer [12-14].
The use of compounds based on olefins as a plasticizer comonomer for the production of high-impact copolymer based on styrene and methyl methacrylate is considered an important area of research [15-20].
Previously, a new method for obtaining OPMM from polypropylene was proposed [21, 22]. Since these macromonomers retain unsatu-rated bonds at the end groups, they can also be easily functionalized with various reagents. As a result, it was possible to obtain new antibacterial oligomers [23] and composite materials based on them [24].
Taking into account these considerations, it seems interesting to use macromonomers of oligoethylene and oligopropylene (OPMM) as comonomers for the chemical modification of PMMA [25-27].
The present article is devoted to the preparation and study of copolymers of methyl methacrylate with an oligopropylene macro-monomer.
The scientific novelty of the study lies in the creation of copolymers of the MMA monomer with high molecular weight 1-alkenes (OPMM) with higher impact strength and elasticity than PMMA, in determining the patterns of the reactions of radical copolymerization of these monomers, the values of the copolymeri-zation constants and the parameters of the microstructure of the obtained copolymers, depending on reaction conditions.
Experimental part
Oligoropylene macromonomer was obtained by one-stage thermal destruction of isotactic polypropylene under special conditions - in a nitrogen atmosphere, in a vacuum distiller at a temperature of 320-3600C, at a pressure of 400-600 mm Hg [21]. Its average molecular weight is 400-600, the coefficient of molecular weight distribution is close to 1.1 and the melting point is 70-720C.
Methyl methacrylate (CH2=C(CHs)COOCHs) is a methyl ester of methacrylic acid, is a colorless oily liquid with an odor. It easily evaporates and ignites. Boiling point is 1010C, melting point is -480C, density it 0.94 g/cm3.
The copolymerization reaction of OPMM with MMA was carried out in a glass ampoule in the presence of 0.2% benzoyl peroxide (BP) using a water bath at 750C for 24 hours. The obtained samples of the copolymer are colorless powders, readily soluble in aromatic solvents and decane.
The IR spectra of the monomers and co-polymers were recorded on an ALPHA IR Fourier spectrometer (BRUKER, Germany) in the frequency range of 600-4000 cm-1.
The intrinsic viscosity values of the co-polymer samples were determined in a decane solution using an Ubbelohde viscometer.
The softening temperature of the copol-ymers was determined by the Vika method on a WPM, VEB Thüringer Industriewerk Rauen-stein device.
The copolymerization constants are found by a graphical method using the Fine-man-Ross equation [28].
Results and discussion
Comparison of the IR spectra of the monomer and the obtained copolymer shows that the intensities of the absorption bands corresponding to the bending and stretching vibrations characterizing the double bond of the vinyl groups of the monomers decrease during copolymerization and are practically not recorded in the IR spectrum of the copolymer (Figures 1a and 1b).
The above and other results support the obtaining of copolymers. Thus, in the IR spectrum of the copolymer, absorption bands belonging to the ether group of methyl methacrylate structural units (1731 u 1161 cm-1), methyl group of oligopropylene units (2841, 2869, 2916, 2952 cm-1) have been identified.
The relative activity of monomers OPMM copolymerization (M1) with MMA (M2), in the radical reaction i.e. copolymerization constants (r1=0.02 and r2=12.20) have been determined graphically using the Fineman-Ross equation. The results are shown in table 1. It has been found that OPMM practically does not enter into the homopolymerization reaction and acts as a more passive monomer in the copolymeri-zation reaction with MMA.
It is known that the copolymerization constant is defined as the ratio of the rate constants (r1 = K11/K12 and r2= K22/K21) of the combination reaction of the active radical center formed from a monomer (or from an elongated chain with a monomer end) with a monomer and another monomer. The value of r1 = 0.02 in the studied monomer pair shows that the radical centers formed by OPMM are practically not bound to their monomer; they interact with MMA molecules in the process of copolymeri-zation. This is due both to the electronic structure of OPMMs and to their large sizes, i.e. with spherical difficulties. The value of the co-polymerization constant for a similar excess of MMA monomer in this reaction can be determined as r2=12.2.
Fig. 1a. IR spectrum OPMM.
Fig. 1b. IR spectrum of OPMM copolymer with MMA.
Thus, MMA is a compound that polymerizes easily and binds MMA molecules at a faster rate when copolymerized with radical center of OPMM formed from this monomer. The resulting copolymer macromolecules with a
statistical structure consist of oligopropylene units and blocks of methyl methacrylate. This is confirmed by the values of the parameters of the microstructure of the synthesized samples of the copolymer.
The values of the copolymerization constants indicate that in the OPMM + MMA system OPMM is prone to copolymerization reaction, and formed copolymer macromolecules consisting of a random structure, OPMM units and blocks formed from MMA. The parameters of the microstructure of the copolymer macro-molecules were calculated from the values of the copolymerization constants (Table 1).
As can be seen from the table, the relative activity of the MMA (M2) monomer is higher during the copolymerization of the used monomers. This is usually associated with the
high activity of MMA in radical transformations, and, on the other hand, with the passivity of 1-alkenes in radical polymerization, as well as with the relatively high molecular weight of OPMM (Figure 2).
The value of the relative activity of OPMM is close to zero, and the relative activity of MMA is very high, which indicates a high probability of obtaining block copolymers. The microstructure parameters calculated from the copolymerization constants of macromolecules also confirm the results expected (Figure 3).
Table 1. Indicators for calculating the relative activity of monomers in the copolymerization reactions of OPMM (M1) and MMA (M2) (in mass, T=70°C, initiator-BP-0.2%, reaction time-1 hour)
The composition of the initial mixture of monomers, mol.% Yield, % Composition of copolymers, mol.% r1 r2 Microstructures of copolymers
M1M2 m1 m2 0.02 12.2 LM 1 LM 2 R
10:90 5.8 0.89 99.11 0.113 110.8 1.79
25:75 6.5 2.63 97.37 1.007 37.6 5.18
50:50 7.9 7.15 92.85 1.02 13.2 14.07
75:25 8.3 16.54 83.46 1.06 5.067 32.64
90:10 12.0 33.38 66.62 1.18 2.36 56.49
LM and LM - the average length of blocks consisting of the corresponding monomeric residues; R - coefficient of the Harvoord block
Fig. 2. Dependence of the composition of copolymers on the composition of the mixture of monomers in the copolymerization reactions of OPMM and MMA.
Fig. 3. Dependence F1 (fr1) /fl-Flz/fl in the reaction of radical copolymerization of OPMM with MMA.
ÇH3 ÇH3 ÇH3
+ m CH2= С—(СН2— СН—)nCH2— СН '
сн, — с - СН
СН-СН,
Table 2. Influence of composition on the properties of copolymers obtained in the copolymerization reactions of OPMM with MMA
№ The amount of OPMM in a mixture of monomers, wt. % The amount of OPMM units in copolymers, wt. % Yield, % M dl/g Softening temperature, 0C
1 0.00 0 80.50 0.70 83
2 0.50 0.25 17.90 0.41 78
3 1.00 1.00 13.93 0.30 73
4 2.50 2.10 10.95 0.18 70
5 5.00 3.25 10.32 0.11 65
The dependences of some properties of the synthesized copolymers on their composition have been studied. The results are presented in Table 2.
As can be seen from Table 2, as the relative amount of OPMM in the mixture of monomers increases, a sharp decrease in the yield and intrinsic viscosity of the copolymers and, accordingly, the value of the average molecular weight is observed. This is naturally associated with the high passivity of OPMM, as well as the transfer of high chain capacity through OPMM in copolymerization reactions.
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metílmetakrílatin polípropílen makromonomerlorí ílo birgopolímerlorínín
ALINMASI VO TODQÍQÍ V.M.Dostuyeva
Oliqopropilen makromonomerinin (Mi) metilmetakrilatla (M2) radikal birgapolimerla§ma reaksiyasi hayata kegirilmi§, reaksiyanin qanunauygunluqlari va mahsullan tadqiq edilmiíjdir Müayyan edilmi§dir ki, bu monomerlarin nisbi aktivliklarinin qiymatlari müvafiq olaraq r1=0.02 va r2=i2.2-dir. Oliqopropilen makromonomeri ügün birgapolimerla§ma sabitinin qiymatinin sifira yaxin olmasi onun homopolimerla§ma reaksiyasina meyilli olmadigini va yalniz birgapolimerla§ma reaksiyalanna ugradigini góstarir. Sintez olunmu§ birgapolimerin bazi xassalarinin onlann tarkibindan asililigi óyranilmi§ va góstarilmi§dir ki, oliqopropilen makromonomerindan formala§an fraqmentin miqdannin artmasi ila birgapolimerlarin yum§alma temperaturu va xarakteristik ózülülüyünün qiymatlari azalir, buna uygun olaraq da orta molekul kütlasinin kaskin azalmasi mü§ahida olunur. Buna sabab birgapolimerla§ma reaksiyalarinda oliqopropilen makromonomerinin passivliyi va zancirin oliqopropilen makromonomerinin vasitasila ótürülmasi reaksiyasinin ba§ verma ehtimalinin yüksak olmasidir.
Agar sozlar: Oliqopropilen makromonomeri, polimetilmetakrilat, birgapolimerla§ma sabithri, zarbaya davamli polimetilmetakrilat.
СИНТЕЗ И ИССЛЕДОВАНИЕ СОПОЛИМЕРОВ МЕТИЛМЕТАКРИЛАТА С ОЛИГОПРОПИЛЕНОВЫМИ МАКРОМОНОМЕРАМИ
В.М. Достуева
Проведена реакция радикальной сополимеризации олигопропиленового макромономера (Mi) с метилмет-акрилатом (M2), изучены закономерности реакции и свойства полученных продуктов. Найдено, что значения относительной активности этих мономеров составляют ri=0.02 и r2=i2.2 соответственно. Тот факт, что значение константы сополимеризации олигопропиленового макромономера близко к нулю, указывает на то, что он не склонен к реакциям гомополимеризации и подвергается только реакции сополимеризации. Изучена зависимость некоторых свойств синтезированного сополимера от их состава и показано, что с увеличением количества фрагмента, образующегося из олигопропиленого макромономера, температура размягчения и значения характеристической вязкости сополимеров снижаются, соответсвенно наблюдается резкое снижение средней молекулярной массы. Это связано с пассивностью олигопропиленового макромономера в реакциях сополимеризации и высокой вероятностью реакции передачи цепи через олигопропиленовый макромономер.
Ключевые слова: Олигоропиленовый макромономер, полиметилметакрилат, константы сополимеризации, ударопрочный полиметилметакрилат.
