CC BY
12
UDC 678.65
T. A. Borukaev, R. Z. Oshroeva, N. I. Samoilyk, G. E. Zaikov
POLYAMIDES AND POLYAMIDOETHER IN MACROMOLECULES CONTAINING A TRIPHENYLMETHANE GROUPS
Keywords: 4,4'-diaminodiphenylmethane, polyamides, polyamidoethers, physical and mechanical properties, the liquid-crystalline
state.
Polyamides and polyamidoether, containing in macromolecules volume of triphenylmethane group are synthesized. The resulting polymer possess high thermal and strength properties, polyamidoether have thermotropic liquid crystal properties.
Ключевые слова: 4,4'- диаминодифенилметан, полиамиды, полиамидоэфиры, физико-механические свойства,
жидкокристаллическое состояние.
Синтезированы полиамиды и полиамидоэфиры, содержащие в объеме макромолекул трифенилметановую группу. Полученный полимер обладает повышенными тепловыми и прочностными свойствами, полиамидоэфир проявляет свойства термотропного жидкого кристалла.
Introduction
Aromatic polyamides (PA) and polyamidoether (PAE) have unique properties such as thermal stability, impact strength, thermal and chemical stability etc [13]. However, the high their melting and softening temperature, limited solubility, significant rigidity of macromolecules complicate the processing of these polymers in the products. Therefore, a great interest of researchers is causing aromatic PA and PAE, which would maintain their inherent high level of physical and mechanical properties, and at the same time were easily processed from solution and melt.
To solve this problem very promising is the use as a starting diamines derivatives of 4,4'-diaminotriphenylmethane. The last ones due to their chemical structure, bulky substituents, can have a beneficial impact on the process ability of polymers. In addition, these diamines -4,4'-diaminotriphenylmethane can easily be obtained in one stage from available compounds with a high output.
Experimental
In the work of the PA and PAE on base of diamines of triarylmethane set (Table 1) have been obtained by means of low-temperature polycondensation and copolycondensation of source monomers in a solution of N-methylpyrrolidone (MP) in an inert atmosphere.
Table 1 - The output and properties of PA and PAE on base of diamines of triarylmethane set
Poly mers* The concen tration of monomer, mol/L m , % о4 The solvent Intrinsic viscosity M, dL/g
I 1 98,3 DEA 1,5
II _„_ 97,1 _„_ 1,2
III _„_ 98,4 _„_ 1,5
IV _„_ 98,1 _„_ 1,3
V 0,6 90,8 MP 0,6
VI _„_ 91,1 _„_ 0,6
I — O _ O NH—^ ^—OH—^ ^—NH—C—/ \— C-"Ô " " . n
II O _ O - NH—^^—OH—^^—NH— C^1 C-. "6 " " . n
III O _ O NH—^ ^—OH—^ ^—NH—C—^ V- C- "Ф" " CH3 J n
IV O _ O M+- C^ V- C- ГФ" -] CH3 n
V H HO,__ O „ O^O - - n
VI H HO^O_ O_O "6" " " " -'n
Note: the Intrinsic viscosity ([q], dL/g) has been determined in a solution of dimethylformamide DMF (0,5 g per 100 ml of DMF) on the Ubbelohde type viscometer at the temperature of 20 C
As monomers have been used 4,4'-diaminotriphenylmethane, hydroquinone and dichlorohydrin of tere- and isophthalic acids. The reaction of obtaining PAE we can be represented as follows:
h2n—v z-1ch^ v- nh2 +
2C1OC
COC1 + HO
-OH
H
-N—A W
CH
Et3N -HCl
H O
// Чч 1 11 // \
O
-C—O
O
O—C-
/ V
3000 - 3100 cm-1 are responsible stretching vibrations of C-H communication aromatic rings (Fig.1).
The introduction of lateral substituents in triphenylmethane, and the use of dichlorohydrin of isophthalic acid to obtain the PA don't lead to significant changes in the IR spectra. In the case of 4,4'-diamino-4"-methyltriphenylamineis observing the disappearance of the bands that correspond to the mono-substituted benzene rings, in General, the nature of the spectrum is preserved.
и
cm--
3400 2800 1600 1000 400
Fig. 1 - The IR spectrum of PA on the basis of 4,4'-diaminotriphenylmethane and dichlorohydrin terephthalic acid
As an HCl acceptor were solvent - MP and triethylamine.
Getting PA with low temperature polycondensation of diamines with dichlorohydrin of tere- and isophthalic acids in solution diethylacetamide (DEA) in an inert gas atmosphere we can be represented by the following scheme:
DEA -2HCl
The structure of the obtained polymer was confirmed using IR spectroscopy (IR spectrometer "Specord M-82", the range of 400 - 4000 cm-1) and elemental analysis. Elemental composition of the products of polycondensation is close to the calculated values.
Results and Discussion
The analyze polymers on basis 4,4'-diaminotriphenylmethane and dichlorohydrin terephthalic acid spectra is allows to establish the presence of the following groups: monosubstituted benzene ring (stripes 700 and 1110 cm-1), 1,4-disubstituted benzene rings (stripes 785, 1015, 1225 and 1320 cm-1), the stretching vibrations of C-C correspond stripes 1510 and 1560 cm-1, carbonyl group - stripe 1700 cm-1, the amino group - the strip with the inflection 3420 cm-1, and several stripes in the region of
In addition, IR spectra for PAE have been removed. The results of the spectrum analysis based on polymer of 4,4'-diaminotriphenylmethane, dichlorohydrin terephthalic acid and p-hydroquinone can detect the presence of the following groups: monosubstituted benzene ring (stripes 700, 720 and 1172 cm-1), 1,4-disubstituted benzene ring (stripes 812, 1016, and 1408 cm-1), the stripes 1508 - 1596 cm-1 correspond to stretching vibrations of C-C bond in aromatic rings, ester linkages - stripes 1732 cm-1, carbonyl, amide groups meet stripes 1636 and 1648 cm-1, as the amino group - the strip with the inflection 3400 cm-1, in addition there are several stripes sin the area 3032 - 3100 cm-1 which correspond to stretching vibrations of C-H bonds and aromatic rings (Fig. 2).
1000
400
3400 2800 1600 Fig. 2 - The IR spectrum of PAE based on 4,4'-diaminotriphenylmethane, hydroquinone and dichlorohydrin terephthalic acid
n
The use of dichlorohydrin isophthalic acid slightly changes the nature of the spectrum. In the spectra (Fig. 3) are detected stripes, corresponding to 1,3-disubstituted benzene nuclei (700, 876 and 1064 cm-1).
A determining process of thermal decomposition of polymers containing -CO-NH- and -C(O)-O- bonds, is a hydrolytic breakdown of amide and ether groups, catalyzed by terminal carboxyl and amino groups.
Aromatic PA are of great interest as polymers which possess high thermal stability [4]. However, the high temperature of their melting and softening limited solubility, significant rigidity of macromolecules complicate the processing of these polymers in the product.
Fig. 3 - The IR spectrum of PAE based on 4,4'-diaminotriphenylmethane, hydroquinone and dichlorohydrin isophthalic acid
We received as PAE through the introduction of ester groups in the main chain. It was interesting to compare the properties of polyamides and polyamidoether based diamines of triarylmethane series.
A study of the thermal stability of PA and PAE have been performed using derivatograph (TGA) Q -1500 by firm MOM (Hungary) in dynamic mode of heating in the temperature range 20 - 600 °C. The study has been conducted in an inert atmosphere and in air. The heating rate of the samples is 2.5 deg/min. Results of thermal analysis are shown in Table 2.
Table 2 - Thermal properties of polyamides and polyamidoether
Polymers Intrinsic viscosity M, dL/g Weight loss at temperature, °C (on air) Softening point, T, оС
10 % 50%
I 1,5 425 50% 300
II 1,2 420 >500 290
III 1,5 415 _„_ 290
IV 1,3 410 _„_ 285
V 0,6 400 _„_ 265
VI 0,6 385 _„_ 255
As the table shows, the maximum thermal stability is PA based on 4,4'-diaminotriphenylmethane and dichlorohydrin terephthalic acid. In [5, 6] it is noted that the thermal stability of PA increases in the number of m, m<m, p<p, p, when using the substituted diamines for the synthesis of the PA, the thermal stability of polymers is slightly decreased. The introduction of macromolecules ester groups in the main chain also leads to a reduction of the thermal stability.
The differential thermal analysis (DTA) curve analysis enables to determine the position of the thermal effects associated with oxidative and thermo-oxidative processes. For PA thermal effects on DTA curves associated with oxidative processes we were observed at a temperature as with a maximum at 290 °C.
Intensive mass loss that meets of the basic thermal oxidativedestruction process, was start at a temperature of 380oC (Fig. 4).
Fig. 4 - Dynamic Thermogravimetric analysis (TGA) of PA on the basis of 4,4'-diaminotriphenylmethane, of dichlorohydrin terephthalic acid (1); Dynamic Thermogravimetric analysis of PAE based on 4,4'-diaminotriphenylmethane, hydroquinone and dichlorohydrin terephthalic acid (2); Differential thermal analysis (DTA) of PA (3)
For PAE thermal effect was observed (DTA) at a temperature of 250 °C, associated with the melting of the polymer. Thermal decomposition located in the range of 360-450 °C, which is lower than the PA. Low temperature resistant PAE compared to the PA can be explained by the activity of the ester group in the process of heating of the sample and a lower value of the energy gap ester bonds in contrast to the amide. The depth of the transformations when heated in air for PA and PAE are much greater than in an inert atmosphere and the maximum weight of the residue when heated to 500 °C, respectively, less than in an inert atmosphere.
The change in physical properties with temperature, you can determine the operating temperature range of the polymer and its processing. In this regard, we have investigated the thermo mechanical properties of the obtained polymers. Studies were performed on the instrument universal measuring device (UMD-70) [7] in the temperature range 20-300 °C in dilatometer mode with a constant heating rate of 5 °C.
The results of dilatometer analysis are presented in Table 2. From the analysis of experimental
data (Table 2), we can conclude that the softening point is higher in the PA than PAE. High softening point of the PA can be explained by the presence of hydrogen bonds formed between the amide groups of adjacent molecules. This results in a net of hydrogen bonds, which pervades the whole mass of PA, as shown by Fuller [8]. The energy of hydrogen bonds is less than the main valence bonds (N-C, C-C), however, due to their significant number in each macromolecule total interaction energy can be considerable.
Introduction to basic chain PA ester groups leads to a decrease of the melting temperature of the polymer. The reduction probably occurs by increasing the flexibility of the chain of macromolecules.
For PA and PAE decrease the softening point in the case of using isophthalic acid instead of terephthalic acid (Table 2). This is because aromatic PA with m-phenylene groups in the chain un like poly-p-phenyleneterephthalamide have «like fiber» location of phenylene cycles [6]. Along the fibre axis, alternately arranged benzene nucleus at an angle of 10 and 20 °C to the axis. Amide groups are almost perpendicular to the plane of the benzene ring, the rotation of which causes the low symmetry of the aromatic m-polyamides and, consequently, minor orderliness, increased solubility and a lower softening point.
As we noted above, PAE based on 4,4'-diaminotriphenylmethane, dichlorohydrin terephthalic acid and hydroquinone is a partially crystalline polymer (degree of crystallinity of about 35%) with melting point 265 oC. For the detection of phase transitions have been used methods of differential scanning calorimetry (DSC), dilatometry and optical microscopy. Observation of PAE (V) in a polarizing microscope with a heating table shows that the polymer melts at 270 0C, exhibiting thermotropic liquid crystalline properties. The polymer melt has a nematic liquid crystal state.
The study of polymers using differential scanning calorimetry ( DSC we were performed on the device "Metlef' at heating rate of 8 °C/min) have been shown that when heated sample V (Fig. 5, curve 1) exothermic effect was being observed at 260 0C associated with the crystallization of the polymer, which is then a thermal melting point. After cooling (cooling rate 5 °C/min) during the second cycle of heating the endothermic effect at a temperature of 265oC (Fig. 4, curve 3) was being detected.
Temperature of isotropization (T), have been defined using the DSC thermograms, is 285 °C. The visual observation of PAE in a polarizing microscope, we could not clearly determine T, the polymer acquires a brownish-carbonized color. This area increases in size. The results of DTA (see above) showed that the polymer V losses 5% of the weight in the field of 290-350 °C. Temperature isotropization of PAE coincides with the thermal decomposition and it is not thermodynamically controlled phase equilibrium. The observed bending of the thermograms (Fig. 5, curves 1 and 3) is associated with the transition to the rubbery state of PAE, which is 195°C.
EXO
ENDO
260
250 2
3
265
\ fi*5
272
100
200
300 Т. С
Fig. 5 - Differential scanning calorimetry (DSC) of PAE based on 4,4'-diaminotriphenylmethane, hydroquinone and dichlorohydrin terephthalic acid: 1 - the first heating of the sample, 2 - cooling, after the first heating and 3 - second heating
Monitoring PAE based on dichlorohydrin isophthalic acid in a polarizing microscope are showed that the polymer is melted at a temperature of 255 °C, it is not showing liquid crystal properties, associated with shortness of rotation of the segmental of chain macromolecules. For that reason, and low values of the melting temperature PROBES on the basis of dichlorohydrin isophthalic acid. Thus, the introduction of the nonlinear circuit unit steam-meta leads to lower degree of order of the macromolecules of polymers.
Thus, aromatic polyamides and polyamidoether with triarylmethane fragments in the main chain have been obtained. The obtained polymers are easily processed from solution and melt. It is found that the synthesized polymers show increased thermal stability, films based on polyamides have high strength characteristics. It is shown that polyamidoether based on dichlorohydrin terephthalic acid exhibits liquid crystalline properties in the temperature range of 270285 °C.
This Work is carried out with the financial support of the Ministry of Education and Science as part of the state task (project code 2199).
References
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7. V.J. Teitelbaum. Thermal analysis of polymers. - Moscow: Science, 1979. - p. 236 [in Russian].
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© T. A. Borukaev - Doctor of Chemistry, Full Professor, Kabardino-Balkarian State University, Nal'chik, Russia, [email protected], R. Z. Oshroeva - Ph.D., Associate Professor, Head of Department, Kabardino-Balkarian State University, Nal'chik, Russia, N. 1 Samoilyk - Ph.D., Associate Professor, Kabardino-Balkarian State University, Nal'chik, Russia, G E. Zaikov -Doctor of Chemistry, Full Professor, Plastics Technology Department, Kazan National Research Technological University, Kazan, Russia.
© Т. А. Борукаев - доктор химических наук, профессор, Кабардино-Балкарский государственный университет, Нальчик, Россия, [email protected], Р. З. Ошроева - кандидат химических наук, доцент, заведующий кафедрой, Кабардино-Балкарский государственный университет, Нальчик, Россия, Н. И. Самойлик - кандидат биологических наук, доцент, Кабардино-Балкарский государственный университет, Нальчик, Россия, Г. Е. Заиков - доктор химических наук, профессор, кафедра Технологии пластических масс, Казанский национальный исследовательский технологический университет, Казань, Россия.
