Synthesis and characterization of novel aromatic poly(amide‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl or 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic diamines

New aromatic diimide‐dicarboxylic acids having kinked and cranked structures, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b), were synthesized by the reaction of trimellitic anhydride with 2,2′‐bis(4‐aminophenoxy)biphenyl (1a) and 2,2′‐bis(4‐aminophenoxy)‐1,1′‐binaphthyl (1b), respectively. Compounds 2a and 2b were characterized by FT‐IR and NMR spectroscopy and elemental analyses. Then, a series of novel aromatic poly(amide‐imide)s were prepared by the phosphorylation polycondensation of the synthesized monomers with various aromatic diamines. Owing to structural similarity, and a comparison of the characterization data, a model compound was synthesized by the reaction of 2b with aniline. The resulting polymers with inherent viscosities of 0.58–0.97 dl g^?1 were obtained in high yield. The polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λ_max values of the poly(amide‐imide)s were also determined. The polymers were readily soluble in polar aprotic solvents. They exhibited excellent thermal stabilities and had 10% weight loss at temperatures above 500 °C under a nitrogen atmosphere. Copyright © 2003 Society of Chemical Industry     

Synthesis and properties of new aromatic poly(ester‐imide)s derived from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl) pyridine and various dihydroxy compounds

A novel class of wholly aromatic poly(ester‐imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32–0.49 dL g^?1 was prepared by the diphenylchlorophosphate‐activated direct polyesterification of the preformed imide‐ring‐containing diacid, 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6‐bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and ¹H NMR spectroscopy and elemental analysis. The ultraviolet λ_max values of the poly(ester‐imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m‐cresol, as well as in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide‐angle X‐ray diffraction. The resulting poly(ester‐imide)s showed nearly an amorphous nature, except poly(ester‐imide) derived from 4,4′‐dihydroxy biphenyl. The glass transition temperatures (T_g) of the polymers determined by differential scanning calorimetry thermograms were in the range 298–342 °C. The 10% weight loss temperatures (T_10%) from thermogravimetric analysis curves were found to be in the range 433–471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry     

Synthesis and properties of poly(amide–imide)s based on N,N′‐bis(4‐carboxyphenyl)‐4,4′‐oxydiphthalimide,p‐aminobenzoic acid and various aromatic diamines

A new diimide–diacid monomer, N,N′‐bis(4‐carboxyphenyl)‐4,4′‐oxydiphthalimide (I), was prepared by azeotropic condensation of 4,4′‐oxydiphthalic anhydride (ODPA) and p‐aminobenzoic acid (p‐ABA) at a 1:2 molar ratio in a polar solvent mixed with toluene. A series of poly(amide–imide)s (PAI, III_a–m) was synthesized from the diimide–diacid I (or I′, diacid chloride of I) and various aromatic diamines by direct polycondensation (or low temperature polycondensation) using triphenyl phosphite and pyridine as condensing agents. It was found that only III_k–m having a meta‐structure at two terminals of the diamine could afford good quality, creasable films by solution‐casting; other PAIs III using diamine with para‐linkage at terminals were insoluble and crystalline; though III_g–i contained the soluble group of the diamine moieties, their solvent‐cast films were brittle. In order to improve their to solubility and film quality, copoly(amide–imide)s (Co‐PAIs) based on I and mixtures of p‐ABA and aromatic diamines were synthesized. When on equimolar of p‐ABA (m = 1) was mixed, most of Co‐PAIs IV had improved solubility and high inherent viscosities in the range 0.9–1.5 dl g^?1; however, their films were still brittle. With m = 3, series V was obtained, and all members exhibited high toughness. The solubility, film‐forming ability, crystallinity, and thermal properties of the resultant poly(amide–imide)s were investigated. © 2002 Society of Chemical Industry     

Synthesis and characterization of novel optically active poly(amide–imide)s containing N,N′‐(pyromellitoyl)‐bis‐L‐valine diacid chloride and 5,5‐disubstituted hydantoin derivatives under microwave irradiation

Pyromellitic dianhydride (1,2,4,5‐benzenetetracarboxylic acid 1,2,4,5‐dianhydide) was reacted with L ‐valine in a mixture of acetic acid and pyridine (3:2) at room temperature, and then was refluxed at 90–100 °C, N,N′‐(pyromellitoyl)‐bis‐L ‐valine diacid was obtained in quantitative yield. The imide–acid was converted to N,N′‐(pyromellitoyl)‐bis‐L ‐valine diacid chloride by reaction with thionyl chloride. Rapid and highly efficient synthesis of a number of poly(amide–imide)s was achieved under microwave irradiation using a domestic microwave oven by polycondensation of N,N′‐(pyromellitoyl)‐bis‐L ‐valine diacid chloride with six different derivatives of 5,5‐disubstituted hydantoin compounds in the presence of a small amount of a polar organic medium that acts as a primary microwave absorber. A suitable organic medium was o‐cresol. The polycondensation proceeded rapidly, compared with conventional melt polycondensation and solution polycondensation and was almost completed within 8 min, giving a series of poly(amide–imide)s with inherent viscosities in the range 0.15–0.36 dl g^?1. The resulting poly(amide–imide)s were obtained in high yield and are optically active and thermally stable. All of the above compounds were fully characterized by Fourier‐transform infrared (FT‐IR) spectroscopy, elemental analysis, inherent viscosity (η_inh) measurements, solubility testing and specific rotation measurements. The thermal properties of the poly(amide–imide)s were investigated by using thermogravimetric analysis. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds

A series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry     

New poly(amide imide)s containing bis(4‐trimellitimidophenyl) sulfone and hydantoin moieties in the main chain: Synthesis and properties

Several new poly(amide imide)s were synthesized through the polycondensation reactions of bis(4‐trimellitimidophenyl) sulfone [N,N′‐(4,4′‐diphenylsulfone) bistrimellitimide] with a number of hydantoin derivatives in a medium consisting of thionyl chloride, N‐methyl‐2‐pyrrolidone, and pyridine. The polycondensations produced a series of novel poly(amide imide)s in high yields with inherent viscosities of 0.20–0.46 dL/g. The resulting poly(amide imide)s were characterized with elemental analysis, viscosity measurements, thermogravimetric analysis, derivative thermogravimetry, solubility testing, and Fourier transform infrared spectroscopy. All the polymers were soluble at room temperature in polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, and N‐methyl‐2‐pyrrolidone. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1776–1782, 2005     

New poly(amide‐imide) syntheses. 24. Synthesis and properties of fluorinated poly(amide‐imide)s based on 2,2‐bis[4‐(trimellitimidophenoxy)phenyl]hexafluoropropane and various aromatic diamines

An imide ring‐performed dicarboxylic acid bearing one hexafluoroisopropylidene and two ether linkages between aromatic rings, 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]hexafluoropropane (II), was prepared from the condensation of 2,2‐bis[4‐(4‐aminophenoxy)phenyl]hexafluoropropane and trimellitic anhydride. A novel series of poly(amide‐imide)s having inherent viscosities of 0.72 ∼ 1.86 dL g⁻¹ was prepared by the triphenyl phosphite‐activated polycondensation from the diimide‐diacid (II) with various aromatic diamines in a medium consisting of N‐methyl‐2‐pyrolidone, pyridine, and calcium chloride. Several of the resulting polymers were soluble in polar amide solvents, and their solutions could be cast into transparent, thin, flexible films having good tensile properties and high thermal stability. The 10% weight loss temperatures were all above 495°C in air or nitrogen atmosphere, and the glass transition temperatures were in the range of 237°–276°C. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 823–831, 1999     

Synthesis and characterization of new poly(amide‐imide)s based on 1,4‐bis(trimellitimido)‐2,5‐dichlorobenzene

A series of new aromatic poly(amide‐imide)s were synthesized by the triphenyl phosphite‐activated polycondensation of the diimide‐diacid, 1,4‐bis(trimellitimido)‐2,5‐dichlorobenzene (I), with various aromatic diamines in a medium consisting of N‐methyl‐2‐pyrrolidone (NMP), pyridine, and calcium chloride. The poly(amide‐imide)s had inherent viscosities of 0.88–1.27 dL g⁻¹. The diimide‐diacid monomer (I) was prepared from 2,5‐dichloro‐p‐phenylenediamine with trimellitic anhydride. All the resulting polymers were amorphous and were readily soluble in a variety of organic solvents, including NMP and N,N‐dimethylacetamide. Transparent, flexible, and tough films of these polymers could be cast from N,N‐dimethylacetamide or NMP solutions. Cast films had tensile strengths ranging from 92 to 127 MPa, elongations at break from 4 to 24%, and initial moduli from 2.59 to 3.65 GPa. The glass transition temperatures of these polymers were in the range of 256°–317°C, and the 10% weight loss temperatures were above 430°C in nitrogen. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 271–278, 1999     

Novel thermally stable poly(ether imide ester)s from 2,6‐bis (4‐aminophenoxy) pyridine

2,6‐Bis (4‐aminophenoxy) pyridine was prepared via reaction of 4‐aminophenol with 2,6‐dichloropyridine in the presence of potassium carbonate in N‐methyl‐2‐pyrrolidone (NMP). This pyridine‐based ether diamine was reacted with two moles of trimellitic anhydride to synthesize related diimide‐diacid (DIDA). A high temperature solution polycondensation reaction of DIDA with different diols in the presence of triethylamine hydrochloride in dichlorobenzene resulted in different poly(ether imide ester)s. The monomer and polymers were fully characterized, and the physical and thermal properties of the polymers were studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 570–576, 2005     

Synthesis and properties of poly(amide imide)s based on 2,2′‐ or 4,4′‐bis(4‐aminophenoxy)biphenyl and various bis(trimellitimide)s

Three series of isomeric poly(amide imide)s (series III, IV, and V) were synthesized by the direct polycondensation of 2,2′‐bis(4‐aminophenoxy)biphenyl (2,2′‐BAPB), 4,4′‐bis(4‐aminophenoxy)biphenyl (4,4′‐BAPB), or their equimolar mixture (2,2′‐BAPB/4,4′‐BAPB = 1/1) with 12 diimide diacids and with triphenyl phosphite and pyridine as condensing agents. A comparison of the physical properties of these three series was also made. The inherent viscosities of series III, IV, and V were 0.25–0.84, 0.25–1.52, and 0.43–1.30 dL g^?1, respectively. Most of the series III polymers showed better solubility because of the non‐para structure, with the solubility order found to be III > V > IV. According to X‐ray diffraction patterns, the amorphous poly(amide imide)s had excellent solubility, whereas the crystalline polymers were less soluble. All the soluble polymers afforded transparent, flexible, and tough films, which had tensile strengths of 57–104 MPa, elongations at break of 3–20%, and initial moduli of 2.05–2.86 GPa. The glass‐transition temperatures (measured by differential scanning calorimetry) were highest for series IV, which contained the rigid 4,4′‐biphenyl units (254–299°C); copolymer series V ranked second (237–277°C), and series III, with crank 2,2′‐biphenyl structures, had the lowest values (227–268°C). The 10% weight‐loss temperatures (measured by thermogravimetric analysis) were close to one another, ranging from 527 to 574°C in nitrogen and from 472 to 543°C in air. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2763–2774, 2002     

Synthesis and characterization of polyamides and poly(amide‐imide)s derived from 2,6‐bis(3‐aminophenoxy)benzonitrile or 2,6‐bis(4‐aminophenoxy)benzonitrile

A series of polyamides and poly(amide‐imide)s was prepared by direct polycondensation of ether and nitrile group containing aromatic diamines with aromatic dicarboxylic acids and bis(carboxyphthalimide)s respectively in N‐methyl 2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. New diamines, such as 2,6‐bis(4‐aminophenoxy)benzonitrile and 2,6‐bis(3‐aminophenoxy)benzonitrile, were prepared from 2,6‐dichlorobenzonitrile with 4‐aminophenol and 3‐aminophenol, respectively, in NMP using potassium carbonate. Bis(carboxyphthalimide)s were prepared from the reaction of trimellitic anhydride with various aromatic diamines in N,N′‐dimethyl formamide. The inherent viscosities of the resulting polymers were in the range of 0.27 to 0.93 dl g^?1 in NMP and the glass transition temperatures were between 175 and 298 °C. All polymers were soluble in dipolar aprotic solvents such as dimethylsulfoxide, dimethylacetamide and NMP. All polymers were stable up to 350 °C with a char yield of above 40 % at 900 °C in nitrogen atmosphere. All polymers were found to be amorphous except the polyamide derived from isophthalic acid and the poly(amide‐imide)s derived from diaminodiphenylether and diaminobenzophenone based bis(carboxyphthalimide)s. Copyright © 2004 Society of Chemical Industry     

Direct synthesis of new soluble and thermally stable poly(urethane‐imide)s from an imide ring‐containing dicarboxylic acid using diphenylphosphoryl azide

The direct preparation of various aromatic poly(urethane‐imide)s from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) using diphenylphosphoryl azide (DPPA) was investigated. The polymers were mainly obtained by the conversion of imide ring‐containing diacid 1 to corresponding di(carbonyl azide) 2 with DPPA and then to diisocyanate 3 through the Curtius rearrangement of compound 2 followed by polyaddition of 3 in different amounts with aromatic dihydroxy compounds. The molecular weights of the resulting poly(urethane‐imide)s were evaluated viscometrically. All of the resulted polymers were thoroughly characterized by spectroscopic methods and elemental analyses. The poly(urethane‐imide)s exhibited an excellent solubility in a variety of polar solvents. Crystallinity nature of the polymers was estimated by means of WXRD. The glass‐transition temperatures of the polymers determined by DSC method were in the range of 191–202°C. The 10% weight loss temperatures of the poly(urethane‐imide)s from their thermal gravimetric analysis curves were found to be in the range of 392–416°C in nitrogen. The films of the resulting polymers were also prepared by casting the solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 869–877, 2006     

Synthesis and characterization of new rigid‐rod and organosoluble poly(amide–imide)s based on 1,4‐bis(trimellitimido)‐2,3,5,6‐tetramethylbenzene

A series of new aromatic poly(amide–imide)s (PAIs) was synthesized by triphenyl phosphite‐activated polycondensation of the diimide–diacid, 1,4‐bis(trimellitimido)‐2,3,5,6‐tetramethylbenzene (I), with various aromatic diamines in a medium consisting of N‐methyl‐2‐pyrrolidone (NMP), pyridine, and calcium chloride. The PAIs had inherent viscosities of 0.82–2.43 dL/g. The diimide–diacid monomer (I) was prepared from 2,3,5,6‐tetramethyl‐p‐phenylenediamine with trimellitic anhydride (TMA). Most of the resulting polymers showed an amorphous nature and were readily soluble in a variety of organic solvents including NMP, N,N‐dimethylacetamide (DMAc), and N,N‐dimethylformamide (DMF). Transparent, flexible, and tough films of these polymers could be cast from DMAc solutions. Their cast films had tensile strengths ranging from 80 to 95 MPa, elongation at break from 10 to 45%, and initial modulus from 2.01 to 2.50 GPa. The 10% weight loss temperatures of these polymers were above 510°C in nitrogen. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1162–1170, 2000     

Microwave‐assisted and classical heating polycondensation reaction of bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine with diisocyanates as a new method for preparation of optically active poly(amide imide)s

A new class of optically active poly(amide imide)s were synthesized via direct polycondensation reaction of diisocyanates with a chiral diacid monomer. The step‐growth polymerization reactions of monomer bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine (BPABTL) (5) as a diacid monomer with 4,4′‐methylene bis(4‐phenylisocyanate) (MDI) (6) was performed under microwave irradiation, solution polymerization under gradual heating and reflux condition in the presence of pyridine (Py), dibuthyltin dilurate (DBTDL), and triethylamine (TEA) as a catalyst and without a catalyst, respectively. The optimized polymerization conditions according to solvent and catalyst for each method were performed with tolylene‐2,4‐diisocyanate (TDI) (7), hexamethylene diisocyanate (HDI) (8), and isophorone diisocyanate (IPDI) (9) to produce optically active poly(amide imide)s by the diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.09–1.10 dL/g. These polymers are optically active, thermally stable, and soluble in amide type solvents. All of the above polymers were fully characterized by IR spectroscopy, ¹H NMR spectroscopy, elemental analyses, specific rotation, and thermal analyses methods. Some structural characterization and physical properties of this new optically active poly(amide imide)s are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1647–1659, 2004     

Synthesis and characterization of poly(ester‐ether‐imide)s derived from 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene

A series of novel aromatic poly(ester‐ether‐imide)s with inherent viscosity values of 0.44–0.74 dL g^?1 were prepared by the diphenylchlorophosphate‐activated direct polycondensation of an imide ring‐containing diacid namely 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene ( 1 ) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. Owing to comparison of the characterization data, an ester‐containing model compound ( 2 ) was also synthesized by the reaction of 1 with phenol. The model compound 2 and the resulted polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λ_max values of the poly(ester‐ether‐imide)s were also determined. The resulting polymers exhibited an excellent organosolubility in a variety of high polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone. They were soluble even in common less polar organic solvents such as pyridine, m‐cresol, and tetrahydrofuran on heating. Crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resulted polymers exhibited nearly an amorphous nature. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 221 and 245°C. Thermal behaviors of the obtained polymers were characterized by thermogravimetric analysis, and the 10% weight loss temperatures of the poly(ester‐ether‐imide)s were found to be over 410°C in nitrogen. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of new optically active poly(amide‐imide‐urethane) thermoplastic elastomers,derived from 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L‐leucine‐p‐aminobenzoic acid) and PEG‐MDI

A new class of optically active poly(amide‐imide‐urethane) was synthesized via two‐step reactions. In the first step, 4,4′‐methylene‐bis(4‐phenylisocyanate) (MDI) reacts with several poly(ethylene glycols) (PEGs) such as PEG‐400, PEG‐600, PEG‐2000, PEG‐4000, and PEG‐6000 to produce the soft segment parts. On the other hand, 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L ‐leucine‐p‐amidobenzoic acid) (2) was prepared from the reaction of 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L ‐leucine) diacid chloride with p‐aminobenzoic acid to produce hard segment part. The chain extension of the above soft segment with the amide‐imide 2 is the second step to give a homologue series of poly(amide‐imide‐urethanes). The resulting polymers with moderate inherent viscosity of 0.29–1.38 dL/g are optically active and thermally stable. All of the above polymers were fully characterized by IR spectroscopy, elemental analyses, and specific rotation. Some structural characterization and physical properties of this new optically active poly(amide‐imide‐urethanes) are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2288–2294, 2004     

Facile synthesis of novel optically active poly(amide‐imide)s containing N,N′‐(pyromellitoyl)‐bis‐l‐phenylalanine diacid chloride and 5,5‐disubstituted hydantoin derivatives under microwave irradiation

Pyromellitic dianhydride (1,2,4,5‐benzenetetracarboxylic acid 1,2,4,5‐dianhydide) (1) was reacted with L‐phenylalanine (2) in a mixture of acetic acid and pyridine (3 : 2) at room temperature, then was refluxed at 90–100°C and N,N′‐(Pyromellitoyl)‐bis‐L ‐phenylalanine diacid (3) was obtained in quantitative yield. The imide‐acid (3) was converted to N,N′‐(Pyromellitoyl)‐bis‐L ‐phenylalanine diacid chloride (4) by reaction with thionyl chloride. Rapid and highly efficient synthesis of poly(amide‐imide)s (6a–f) was achieved under microwave irradiation by using a domestic microwave oven from the polycondensation reactions of N,N′‐(Pyromellitoyl)‐bis‐L ‐phenylalanine diacid chloride (4) with six different derivatives of 5,5‐disubstituted hydantoin compounds (5a–f) in the presence of a small amount of a polar organic medium that acts as a primary microwave absorber. Suitable organic media was o‐cresol. The polycondensation proceeded rapidly, compared with the conventional melt polycondensation and solution polycondensation, and was almost completed within 10 min, giving a series of poly(amide‐imide)s with inherent viscosities about 0.28–0.44 dL/g. The resulting poly(amide‐imide)s were obtained in high yield and are optically active and thermally stable. All of the above compounds were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity (η_inh), solubility test and specific rotation. Thermal properties of the poly(amide‐imide)s were investigated using thermal gravimetric analysis (TGA). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 516–524, 2004     

Synthesis and characterization of organosoluble poly(arylate‐imide)s prepared from direct polycondensation of bis(trimellitimide)‐diacids and various bisphenols

Three diimide‐diacids, 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]hexafluoropropane ( I‐A ), 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]propane ( I‐B ), and 5,5′‐bis[4‐ (4‐trimellitimidophenoxy)phenyl]hexahydro‐4,7‐methanoindan ( I‐C ), were prepared by the azeotropic condensation of trimellitic anhydride with three analogous diamines. Three series of alternating aromatic poly(arylate‐imide)s, having inherent viscosities of 0.41–0.82 dL/g, were synthesized from these diimide‐diacids ( I‐A , I‐B , and I‐C ) with various bisphenols by direct polycondensation using diphenyl chlorophosphate and pyridine as condensing agents. All of the polymers were readily soluble in a variety of organic solvents such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, and even in the less polar tetrahydrofuran. These polymers could be cast into transparent and tough films, which had strength at break values ranging from 73 to 98 MPa, elongation at break from 6 to 11%, and initial modulus from 1.6 to 2.2 GPa. The softening temperatures of the polymers were recorded at 145–248°C. They had 10% weight loss at a temperature above 450°C and left 35–51% residue even at 800°C in nitrogen. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3818–3825, 2003     

New poly(amide–imide)s syntheses. 17. Preparation and properties of poly(amide–imide)s derived from N-phenyl-3,3-bis[4-(4-aminophenoxy)-phenyl]phthalimidine,trimellitic anhydride,and various aromatic diamines

A dicarboxylic acid ( 1 ) bearing two phthalimide rings was prepared by the condensation of N-phenyl-3,3-bis[4-(4-aminophenoxy)phenyl]phthalimidine and trimellitic anhydride. A new family of poly(amide–imide)s having inherent viscosities of 0.65–1.65 dl/g was prepared by the triphenyl phosphite activated polycondensation of the diimide–diacid 1 with various aromatic diamines in a medium consisting of N-methyl-2-pyrrolidone (NMP), pyridine, and calcium chloride. All the resulting polymers showed an amorphous nature and were readily soluble in polar solvents such as NMP and N,N-dimethylacetamide. The soluble poly(amide–imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range 249–340°C and the 10% weight loss temperatures were above 545°C in nitrogen.     

Synthesis and properties of new poly(amide‐imide)s based on 2,5‐bis(trimellitimido)chlorobenzene

A series of new aromatic poly(amide‐imide)s were synthesized by the triphenyl phosphite‐activated polycondensation of the diimide‐diacid, 2,5‐bis(trimellitimido)chlorobenzene (I) with various aromatic diamines in a medium consisting of N‐methyl‐2‐pyrrolidone (NMP), pyridine, and calcium chloride. The poly(amide‐imide)s had inherent viscosities of 0.76–1.42 dL g⁻¹. The diimide‐diacid monomer (I) was prepared from 2‐chloro‐p‐phenylenediamine with trimellitic anhydride. Most of the resulting polymers showed an amorphous nature and were readily soluble in a variety of organic solvents, including NMP and N,N‐dimethylacetamide. Transparent, flexible, and tough films of these polymers could be cast from N,N‐dimethylacetamide or NMP solutions. Their cast films had tensile strengths ranging from 74 to 95 MPa, elongations at break from 7 to 11%, and initial moduli from 1.38 to 3.25 GPa. The glass transition temperatures of these polymers were in the range of 233°–260°C, and the 10% weight loss temperatures were above 450°C in nitrogen. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1691–1701, 1999