CC BY
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ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)
UDC 678.01:54.541.64:547:512
PREPARATION OF OPTICAL TRANSPARENT COMPOSITES ON THE BASIS OF BUTYL METHACRYLATE WITH a-METHYL STYRENE
S.B.Mamedli1, Q.Q.Mirguseinov2, A.H.Rahimli2, R.A.Akhmedova\ Ch.H.Ismayilova3
institute of Polymer Materials of Azerbaijan National Academy of Sciences 2Azerbaijan State University of Oil and Industry Azerbaijan Medical University
seide.mamedli@yandex.ru
Received 25.11.2021 Accepted 20.12.2021
The process of radical binary copolymerization of butyl methacrylate and a-methyl styrene in a solvent has been carried out and optically transparent copolymers at various molar ratios have been synthesized. The copolymers synthesized based on butyl methacrylate and a-methyl styrene have relatively high re-
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fraction coefficient ( nD =1.5880) and transmission values (about 86%). The copolymerization constants values (r1 and r2) of the above-mentioned monomer pairs have been found and Q-e parameters have been calculated. The microstructure of the obtained copolymer samples of the butyl methacrylate with a-methyl styrene has been determined.
Keywords: a-methyl styrene, butyl methacrylate, optically transparent materials, copolymerization, irradiation, light transmission, microstructure.
doi.org/10.32737/0005-2531-2022-1-34-40
Introduction
One of the most modern directions of the development of optically transparent polymers is the synthesis of binary or ternary copolymers with a complex of unique properties. Such optical transparent polymer compounds with good light transmission in addition have high physical-mechanical properties and can be widely used as optical lenses in devices suitable for opto- and micro-optoelectronics [1-5]. The most spreading optically transparent polymers are obtained from methacrylate and its esters [69]. The polymethylmethacrylate (PMMA) has the highest light transmission index [10]. In addition, PMMA practically does not contain harmful substances [11, 12] and is a much better choice for laser cutting. It is often preferred for its moderate properties, simplicity of handling and treatment, and also low cost [13]. The lacks of these polymers are thermal instability, low adhesion and high water absorption during exploitation and storage. Modifying PMMA with other substances, these lacks can be eliminated [14, 15]. The unmodified PMMA behaves brittle under load, especially under the action of impact force and has been more subjected to scratches than usual inorganic glass,
but modified PMMA can sometimes provide high strength.
Polystyrene (PS) as an optically transparent polymer takes the second place on exploitation. PS has high dielectric properties, transparency and chemical resistance, simple and relatively easy treatment technology and due to these qualities it is very important as a transparent polymer for general use [16, 17]. However, low adhesion, thermal stability and impact resistance also limit the use of polystyrene. Overcoming these lacks of PS and preparation of more qualitative transparent materials can be achieved by modification of PS with various and polyfunctional substances, and also by functionalization of styrene and its copolymeri-zation with other monomers, including methac-rylates [18-20].
With the aim of overcoming of the above-mentioned lacks of optically transparent materials, the copolymers on the basis of butyl methacrylate (BMA) and a-methyl styrene (a-MC) have been synthesized. The copolymers of this type are in great demand in various fields of technology and for creation of optically transparent materials with the best physical and physical-mechanical properties. This work has
been devoted to the discussion of the regularities of the copolymerization reaction of BMA with a-MS and the discussion of the results of the investigation of optical transparency and other properties of the obtained copolymer.
Experimental part
The radical binary copolymerization process of BMA with a-MS was carried out at temperature 600C in sterile ampoules in a thermostat in the presence of a radical initiator of dinitrile azobisisobutyric acid (AIBN). BMA and a-MS was copolymerized at various molar ratios. The obtained copolymer was purified by twofold precipitation from benzene solutions with methanol and dried at 300C in a vacuum (15-20 mm merc.c.).
The structure of the polymer has been revealed on the basis of IR spectral analysis, the composition of the obtained copolymer samples has been calculated on the basis of chemical and elemental analysis [21]. The obtained BMA copolymer with a-methyl styrene is dissolved in chloroform, benzene, CCl4, etc.
The IR spectra of the initial monomers and copolymer have been registered on the spectrometer «Agilent Cary 630 FTIR» of firm «Agilent Technogies», PMR spectra on the spectrometer «Fourier» of firm «Bruker» (GFR) (300.18 MHz) in a solution of deuterated chloroform.
The turbidimetric titration was carried out at 200C on the spectrometer KFK-2 on methodology [22].
Using the equation given in [23], the parameters of the copolymer microstructure were determined.
The refractive index of the obtained co-polymer samples was determined by means of equipment Anton Paar Abbemat 200. The spectral transmission coefficient of BMA samples with a-MS was measured on the spectrophotometer SF-46 in the wavelength range of 2001000 nm.
Results and discussion
It has been carried out the turbidimetric titration for clarification whether homopolymers of monomers are formed during their co-
polymerization reaction. For this case, the reaction product was dissolved in benzene and the various fractions were obtained by consecutive addition of definite quantities of precipitator (ethanol). The fractional and chemical (determination of double bonds) and IR spectral analyses of these fractions have been carried out and it has been found that the results practically are not differed. This fact indicates that BMA and a-MC homopolymers are not formed in the investigated binary system. The reaction product consists of a copolymer of these monomers, which has been also confirmed by turbodimetric titration of this solution in benzene; there is only one maximum on the differential curves obtained as a result of turbodimetric titration of the copolymer, and the integral curves correspond to a monotonically increasing function (Figure 1).
The structure of polymer on the basis of BMA and a-MS has been confirmed by the methods of IR and PMR spectroscopy, and its composition - by elemental analysis.
In the IR spectrum of the copolymer of BMA + a-MS there are absorption bands in the field of vibrations of benzene ring (valence vibrations of C-H bond at sp2-hybrid carbon atom - 3026 cm-1; the valence vibrations of C=C skeleton at 1452 cm-1) and unplanar deformation vibrations of =C-N (697 cm-1) bond, and also characterizing the structural fragments of butyl-methacrylate (absorption band at 1720 cm-1 and 1178 cm-1 indicating the presence of groups -C=O and -C-O-, respectively, i.e. ester groups) (Fig.2). Along with this, in the IR spectrum of the synthesized copolymer samples there is an absorption band in the field of 2800^3000 cm-1 corresponding to the valence vibrations of C-H bond in the aliphatic CH3, -CH2 and CH The comparison of IR spectra of mixtures of the used monomers and copolymers obtained on their basis shows that unlike a mixture of monomers in the spectra of copolymers obtained at all molar ratios of comonomers, the absorption bands corresponding to valence vibrations of C=C bonds of vinyl groups are absent. This is confirmed by the results of the PMR analysis. groups.
D2
2.0 1.5 1.0 0.5
I
7 4 \ w
у
• 1
AD/ДТ
2.0 1.5 1.0 0.5
0.3 0.4 0.5 Y
Fig. 1. Turbidimetric titration of copolymer of BMA + a-MS (1 - differential, 2 - integral).
Fig.2. IR spectra of BMA + a-MS
In the PMR spectrum of the copolymer, the signals characteristic for aromatic nucleus protons at 6.60-7.30 ppm have been detected (Fig. 3). In the PMR spectra of copolymers obtained at various molar ratios, the signals at 5 = 5.7-6.41 ppm corresponding to the double
bonds of the vinyl group are also absent. This indicates the course of copolymerization with the opening of these double carbon bonds.
It can be concluded that the reaction of radical copolymerization of BMA and a-MS proceeds on to the following scheme:
SftME 1H PMI BM*tBt
Г2 ■ Acquisition Р»гччг»г»:
Data 2021102»
Ti»a~ 14.3t
INSTRUM P00RIEB50C
PBCBIID 5 ЛШ1 DDL 13C-1
PULPRQG ttfSC
TD 327«
SOLVENT CDC13
DS 0
' г ■ ■ ■ ■ Г * ■1 I.....I.... I.... I .... I ■■■■,■■■.!■ T-, -,, ■■.-.-., ,■>.,....,.....,----,.....r-----------,-----
9 5 Э.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.S 4.0 3.5 3.0 2.5 2.0 1-5 1.0 0 5 ppm
Fig.3. PMR spectra of BMA + a-MS
fH3 CH3 fH3 CH3
n CH2=C + m CH2=Ç -► -f-CH2— Ç 4-fcH—i -
à I й ^
C4H9 C4H
Scheme
The obtained copolymer samples are white powders, soluble in CCl4, chloroform and benzene.
For determination of the dependence of the composition of the synthesized copolymer on the composition of the initial mixture of monomers, the copolymerization process was carried out at various molar ratios of BMA (M1) and a-MS (M2) (Table 1). According to the results of IR spectroscopy and elemental analysis, the content of m1 and m2 links in the copolymer has been determined.
It has been established that the copoly-merization constants value of BMA and a-MS
less than one (r1=0,50 and r2 =0,48), i.e., BMA + a-MS shows a close activity, as a result, the copolymer practically alternating structures should be formed [24, 25]. According to the values of these constants, the consumption rate of these monomers during the reaction is almost the same. However, at a degree of conversion 70-75%, the consumption of styrene is decreased, which has been connected with decrease of the solubility of styrene in the forming reaction medium. As a result, this fact leads to heterogeneity of the copolymer structure during deep conversion of monomers.
Table 1. The reaction conditions of the radical copolymerization of BMA + a-MS and the compositions of the obtained copolymers (initiator - 0.5% AIBN, solvent - benzene, degree of conversion <10%, T = 333K).
№ Composition of the initial mixture, mol.% Composition of copolymers, mol.% Copolymerization constants rrr2 Light transmission, %
M1 M2 mi m2 T1 r2
1 10 90 16,56 83,44
2 25 75 32,35 67,65
3 50 50 50,336 49,664 0,5 0,48 0,24 86
4 75 25 68,31 31,69
5 90 10 83,926 16,074
Qi=0.24, ei=0.963; Q2=0.72, e2=-0.23
Table 2. Microstructure parameters of copolymers of BMA and a-MS obtained at various initial molar ratios of monomers
№ Composition of the initial mixture, mol.% Composition of copolymers, mol.% Copolymer microstructure
M1 M2 m1 m2 LM1 lm2 R
1 10 90 16,56 83,44 1,05 5,32 31,39
2 25 75 32,35 67,65 1,166 2,44 55,45
3 50 50 50,336 49,664 1,5 1,48 67,11
4 75 25 68,31 31,69 2,5 1,16 54,64
5 90 10 83,926 16,074 5,5 1,05 30,51
*LM and Lm2 - average length of blocks of monomer link; R - Harwood 's block factor
It is seen from Table 2 that the average length of Mi (LMi) blocks in the composition of copolymer macromolecules is increased with an increase of molar quantity of BMA. For the system of BMA + a-MS, the largest Harwood constant values are fixed in the range of BMA + a-MS = (50 - 50):(30 - 70) mol %.
The copolymer of BMA + a-MS has positive properties both of BMA homopolymer and a-MS, the polymer - with more unique properties (n20 =1.5880) than BMA and a-MS. The refraction index of the synthesized polymer has been confirmed by the device Anton Paar Ab-bemat 200. The refractive index of the copoly-mer presented in this paper is higher than at PMMA (1,491). Most likely, this difference has been connected with the second and third structures of the obtained copolymer.
It has been detected that the synthesized polymer also has a sufficiently high light transmission value (86%). These qualities allow to use the copolymer on the basis of BMA and a-MS in optics and in the production of lenses for microelectronics.
Conclusions
The radical copolymerization with BMA and a-MS has been carried out. The structure of the synthesized copolymer has been confirmed
by IR and PMR spectra, and the composition has been determined by a method of elemental analysis. The copolymerization reaction of the investigated monomer system was carried out at various molar ratios of monomers and their low conversion depth (10-12%), there have been detected the quantity of links of type m1 and m2 in the copolymer. It was found that the relative activity of BMA in the polymerization reaction of BMA and a-MS is greater than the activity of styrene monomer (r1>r2), r1=0,50, r2=0,48. It has been established that the obtained copoly-mers of BMA + a-MS have a high optical transparency ( n^0 =1.5880) and a close light transmission index (86%). The dependence of the light transmission of the polymer BMA + a-MC on the composition and microstructure of the polymer has been determined.
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BUTÍLMETAKRÍLATIN a-METÍLSTÍROL ÍLO BÍRGOPOLÍMERÍ OSASINDA OPTÍKÍ §OFFAF
KOMPOZÍTLORÍN ALINMASI
S.B.Mammadli, Q.Q.Mirhüseynov, e.H.Rahimli, RO.ehmadova, C-H.Ísmayilova
Butilmetakrilatm a-metilstirol ila halledicida radikal binar birgapolimerla§ma reaksiyasi hayata kegirilmi§ va monomerlarin müxtalif mol nisbatlarinda optiki §affaf birgapolimerlar sintez edilmi§dir. Müayyan edilmi§dir ki,
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butilmetakrilat va a-metilstirol asasinda sintez edilmi§ birgapolimerlar kifayat qadar yüksak ¡jüasindirma (nD =1.5880) va i§iqburaxma göstaricilarina (86%-a yaxin) malikdir. Qeyd edilan monomer cütünün birgapolimerla§ma sabitlari (r1=0.50 va r2=0.48) tayin edilmi§ va Q-e parametrlari hesablanmi§dir. Butilmetakrilatin a-metilstirol ila birgapolime-rinin mikroqurulu§ göstaricilari tayin edilmi§dir.
Agar sözlzr: a-metilstirol, butilmetakrilat, optiki §affaf materiallar, birgapolimerla^ma, jüasindirma, i§iqburaxma, mikrostruktur.
ПОЛУЧЕНИЕ ОПТИЧЕСКИХ ПРОЗРАЧНЫХ КОМПОЗИТОВ НА ОСНОВЕ БУТИЛМЕТАКРИЛАТА
И a-МЕТИЛСТИРОЛОМ
С.Б.Мамедли, Г.Г.Миргусейнов, А.Г.Рахимли, Р.А.Ахмедова, Ч.О.Исмайлова
Проведен процесс радикальной бинарной сополимеризации бутилметакрилатаи a-метилстирола в растворителе и синтезированы оптически прозрачные сополимеры в различных мольных соотношениях сомономеров. Было обнаружено, что сополимеры, синтезированные на основе бутилметакрилата и a-метилстирола, имеют
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относительно высокие значения коффицента проломления (^ =1.5880) и пропускание (около 86%). Найдены значения константы сополимеризации (r1 и r2) вышеуказанных мономерных пар и рассчитаны параметры Q-e. Определена микроструктура полученных образцов сополимера бутилметакрилата с a-метилстиролом.
Ключевые слова: a-метилстирол, бутилметакрилат, оптически прозрачные материалы, сополимеризация, светопропускание, микроструктура.
