научная статья по теме PREPARATION OF NEW POLY(ETHER-AMIDE-IMIDE)S FROM 1,4-BIS-[4-(TRIMELLITIMIDO)PHENOXY]BUTANE AND AROMATIC DIAMINES VIA DIRECT POLYAMIDATION Физика

ВЫСОКОМОЛЕКУЛЯРНЫЕ СОЕДИНЕНИЯ, Серия Б, 2011, том 53, № 6, с. 960-967

ПОЛИКОНДЕНСАЦИЯ

УДК 541.64:547.553

PREPARATION OF NEW POLY(ETHER-AMIDE-IMIDE)S FROM M-£/s-[4-(TRIMELLITIMIDO)PHENOXY]BUTANE AND AROMATIC DIAMINES VIA DIRECT POLYAMIDATION1 © 2011 г. Kh. Faghihi, M. Shabanian, and Z. Mirzakhanian

Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Faculty of Science,

Arak University, Arak, 38156, Iran e-mail: k-faghihi@araku.ac.ir Received September 3, 2010 Revised Manuscript Received December 2, 2010

Abstract—Several new Poly(ether-amide-imide)s were prepared by direct polycondensation reactions of 1,4-bis-[4-(trimellitimido)phenoxy]butane with various aromatic diamine. Two direct polycondensation techniques were used: direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone/triphenyl phosphite/calcium chloride/pyridine and direct polycondensation in a tosyl chloride/pyridine/N,N-dime-thylformamide system. All the monomers and polymers were fully characterized by means of FTIR, 1H-NMR spectroscopy and elemental analyses and properties of the polymers including solution viscosity, thermal behavior and solubility were studied.

INTRODUCTION

High-performance polymers are an important class of polymers and their applications are growing steadily. Many studies of new polymer syntheses have been focused on the preparation ofhigh-performance polymers. In general, they show high thermal stability, good chemical resistance and excellent mechanical properties. The incorporation of rigid segments in the polymer chain, especially in polyamide and polyimide, is an effective method to enhance the thermal stability. Although poly-imides have higher thermal stability than polyamides, they are generally insoluble and infusible in the imide form [1]. Thermal resistance of polyamides is lower than that of polyimides, but polyamides have better solubility and processability than polyimides [2].

Solubility of polyimides have been targeted by several means, such as introduction of flexible linkages, bulky substituents or bulky units in the polymer backbone incorporation of alicyclic or noncoplanar units [3—5].

Poly(amide-imide)s are one of the important co-polymers that show good balance between process-ability and thermal stability [6—11].

Poly(ether-imide) (PEI) is a high-performance thermoplastic with high thermal stability (Tg « ~ 220° C), and remarkable modulus of elasticity and tensile strength. PEI is used in advanced parts in electrical and electronics industry, in aircraft applications and in the automotive market [12, 13].

We synthesized a new series of poly(ether-amide-im-ide)s via reaction of diacid 6 containing ether and imide units with different diamines 7a—f. Reaction of the prepared diamine 4 with trimellitic anhydride 5 afforded a diimide-diacid compound 6. Polycondensation reaction of this diacid with six different diamines with two different methods was prepared new organosoluble poly(ether-amide-imide)s. Below shown reactions of preparing starting compounds and finishing polymers:

4

Scheme 1. Synthesis of diamine 4.

Статья печатается в представленном авторами виде.

1

O

O

AcOH/Py (3 : 2) Reflux

O

Scheme 2. Synthesis of diacid 6.

O

O

7d 7e 7f

Scheme 3. Synthesis of PEAIs 8a—f by two different methods.

EXPERIMENTAL

Materials

All chemicals were purchased from Fluka Chemical Co. (Switzerland), Aldrich Chemical Co. (Milwaukee), Merck Chemical Co. (Germany) and Acros Organics N.V/S.A (Belgium).

Techniques

'H-NMR and 13C-NMR spectra were recorded on a Bruker 300 MHz instrument (Germany). Fourier transform infrared (FTIR) spectra were recorded

on Galaxy series FTIR 5000 spectrophotometer (England). Spectra of solid were performed by using KBr pellets. Vibration transition frequencies were reported in wave number (cm-1). Band intensities were assigned as weak (w), medium (m), shoulder (sh), strong (s) and broad (br). Inherent viscosities were measured by a standard procedure by using a Technico® Merk Viscometer. Thermal Gravimetric Analysis (TGA) data for polymers were taken on a Mettler TA4000 System under N2 atmosphere at rate of 10 grad/min. Elemental analyses were performed by Vario EL equipment.

Monomer Synthesis

1,4-éis-[4-nitrophenoxy]butane 3

(6.00 g, 43.11 mmol) of 4-nitrophenol 1 and (2.97 g, 21.55 mmol) of dry K2CO3 in 30 ml dimethyl formamide (DMF) were added in a 100 ml round-bottomed flask. Then a solution of (4.46 g, 20.67 mmol) 1,4-dibromobutane 2 in 5 ml dry DMF was added drop-wise to reaction mixture. The reaction mixture was heated for 6 h at 120°C, then was cooled and poured onto crushed ice. The precipitated white product was collected by filtration, dissolved in CH2Cl2 and washed successively with NaOH (2 M), HCl (1 M) and water. Then CH2Cl2 solution was dried over Na2SO4 and concentrated in vacuum and product was recrystallized from ethanol, affording 4.59 g (65.4%) ofwhite solid 3, m.p: 140-142°C, FTIR (KBr, cm-1): 3058 (w), 1609 (s), 1534 (s), 1411 (m), 1348 (s), 1181 (s), 1111 (s), 987 (s), 852 (s), 756 (m), 702 (s), 543 (m). 1H-NMR (300 MHz, DMSO-d6, TMS): SH, p.p.m. 8.17-8.20 (d, 4H), 7.12-7.15 (d, 4H), 4.19 (t, 4H), 1.92 (m, 4H) ppm. 13C-NMR (300 MHz, DM-SO-d6): 8C, p.p.m. 164.37, 142.78, 126.31, 115.41, 68.10, 26.17 ppm. Elemental analysis: calculated for C16H16N2O6, %: C, 57.83; H, 4.85; N, 8.43; found, %: C, 57.68; H, 4.81; N, 8.33.

1,4-A/s-[4-aminophenoxy]butane 4

Into a 100 ml round-bottomed flask were added (1.00 g, 3.67 mmol) of 1,4-èis-[4-nitrophenoxy]bu-tane 3 and 0.1 g of 10% Pd-C, and 20 ml of ethanol were introduced into a 100-ml round-bottomed flask to which 7 ml of hydrazine monohydrate was added drop-wisely over a period of 1 h at 85°C. After the complete addition, the reaction was continued at reflex temperature for another 5 h. Then, the mixture was filtered to remove the Pd-C and the filtrate was poured into water and dried to afford 0.71 g (87%).

1,4-éis-[4-(trimellitimido)phenoxy]butane 6

Into a 100-ml, round-bottom flask, 0.204 g (0.75 mmol) of 1,4-èis-[4-aminophenoxy]butane 4, 0.29 g (1.5 mmol) of trimellitic anhydride 5, 20 ml of a mixture of acetic acid and pyridine (3 : 2) and a stirring bar were placed. The mixture was stirred at room temperature overnight and then refluxed for 4 h. After that time the solvent was removed under reduced pressure, and the residue was dissolved in 100 ml of cold water; then, 5 ml of concentrated HCl was added. The solution was stirred until a brown precipitate formed, and then the precipitate was filtered off and dried in vacuum to give 0.414 g (89%) of dicarboxylic acid 6: mp > 320°C, FTIR (KBr, cm-1): 2500-3500 (m, br), 1782 (w), 1720 (s, br), 1610 (w), 1512 (m), 1388 (s, br), 1292 (w), 1248 (m), 1176 (w), 1099 (w), 1055 (w), 976 (w), 823 (m), 721 (s), 524 (m) cm-1. 1H-NMR (300 MHz, DMSO-d6, TMS): 8H, p.p.m. 12.79 (s, br,

2H), 8.39-8.42 (d, 2H), 8.29-8.39 (s, 2H), 8.04-8.07 (d, 2H), 7.34-7.37 (d, 4H), 7.06-7.11 (d, 4H), 4.12 (t, 4H), 1.88-1.93 (m, 4H) ppm. Elemental analysis:

: C, 65.81; H, 3.90; N, : C, 65.71; H, 3.88; N, 4.50.

calculated for C34H24N2O10 4.51; found,

Polymer Synthesis

Poly(amide-imide)s 8a—f were synthesized by two different methods in the following:

Method A: Direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/tri-phenyl phosphite (TPp)/calcium chloride (CaCl2)/ pyridine (Py)

0.17 g (0.275 mmol) of 1,4-to-[4-(trimellitimi-do)phenoxy]butane 6, 0.275 mmol of diamine, 0.1 g (0.9 mmol) of calcium chloride, 0.84 ml (3.00 mmol) of triphenyl phosphite, 0.1 ml of pyridine and 1.5 ml N-methyl-2-pyrrolidone (NMP) were placed into a 25-ml round-bottomed flask, which was fitted with a stirring bar. The reaction mixture was heated under reflux at 120°C for 9 h. Then, the reaction mixture was poured into 50 ml of methanol and the precipitated polymer was collected by filtration and washed thoroughly with hot methanol and dried at 60°C for 10 h under vacuum.

Method B: Direct Polycondensation in a Tosyl Chloride (TsCl)/Pyridine (Py)/N,N-Dimethylforma-mide (DMF) System

A solution of 0.1 ml pyridine, 0.078 g (0.411 mmol) of TsCl after 30 min stirring at room temperature was treated with 0.1 ml (1.36 mmol) of DMF for additional 30 min. The reaction mixture was added dropwise to a solution 0.084 g (0.137 mmol) of diacid 6 in 0.2 ml of pyridine. The mixture was maintained at room temperature for 30 min, and then to this mixture a solution 0.137 mmol of diamine in 0.1 ml of pyridine was added dropwise and the whole solution was stirred at room temperature for 30 min and at 110°C for 2 h. As the reaction proceeded, the solution became viscous, then was precipitated in 50 ml of methanol and filtered off, dried under vacuum.

RESULTS AND DISCUSSION

Monomer Synthesis

1,4-Ws-[4-aminophenoxy]butane 4 was synthesized according our previous work [14]. At first 1,4-¿is-[4-nitrophenoxy]butane 3 was prepared by the reaction of two equimolars 4-nitrophenol 1 and one equimolar 1,4-dibromobutane 2. Then dinitro compound 3 was reduced by using 10% Pd-C, ethanol and hydrazine monohydrate (Scheme 1).

As shown in Scheme 2, the dicarboxylic acid 6 was obtained by the condensation of the appropriate diamine 4 with two mole equivalents of trimellitic anhydride 5 in refluxing mixture of glacial acetic acid and

a

HO

о , о

-i f e

OCH 2CH 2CH2CH2O N

O O

OH

O

O

14 12 10 8 6 4 2

§h> PPm

Fig. 1. 'H-NMR spectrum of diacid 6.

pyridine. The condensation reaction between the amines and anhydride groups, as well as the subsequent cyclodehydration reaction was carried out in the heterogeneous solution. The chemical structure and purity of dicarboxylic acid 6 was proved with elemental analysis, FTIR, 'H-NMR spectroscopy. The FTIR spectrum of the dicarboxylic acid 6 showed absorption bands around 2500-3500 cm-1 (acidic H's), 1782 cm-1 (asymmetric imide C=O stretching), 1720 (symmetric imide C=O stretching and acid C=O stretching), and 1388 cm-1 (

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