Synthesis and characterization of a positive‐working,aqueous‐base‐developable photosensitive polyimide precursor

A positive‐working, aqueous‐base‐developable photosensitive polyimide precursor based on poly(amic ester)‐bearing phenolic hydroxyl groups and a diazonaphthoquinone photosensitive compound was developed. The poly(amic ester) was prepared from a direct polymerization of 2,2′‐bis‐(3‐amino‐4‐hydroxyphenyl)hexafluoropropane and bis(n‐butyl)ester of pyromellitic acid in the presence of phenylphosphonic dichloride as an activator. Subsequently, the thermal imidization of the poly(amic ester) precursor at 300°C produced the corresponding polyimide. The inherent viscosity of the precursor polymer was 0.23 dL/g. The cyclized polyimide showed a glass‐transition temperature at 356°C and a 5% weight loss at 474°C in nitrogen. The structures of the precursor polymer and the fully cyclized polymer were characterized by Fourier transform infrared spectroscopy and ¹H‐NMR. The photosensitive polyimide precursor containing 25 wt % diazonaphthoquinone photoactive compound showed a sensitivity of 150 mJ/cm² and a contrast of 1.65 in a 3 μm film with 1.25 wt % tetramethylammonium hydroxide developer. A pattern with a resolution of 10 μm was obtained from this composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 352–358, 2002     

High‐performance copoly(benzimidazole‐benzoxazole‐imide) fibers: Fabrication,structure, and properties

Novel high‐performance copolyimide (co‐PI) fibers containing benzimidazole and benzoxazole ring in the main chain were prepared by a two‐step spinning via the poly(amic acid)s. Effects of the incorporated benzimidazole and benzoxazole units on the micro‐structure and properties of co‐PI fibers were investigated. Fourier transform infrared (FTIR) results indicated that hydrogen bonding is formed in the co‐PI fibers. The co‐PI fibers exhibited discernible crystallization peaks at 14°～15° and 23°～26° (2θ), showing crystalline‐like structure. Moreover, the packing type of benzimidazole‐imide units determined the macromolecules packing of co‐PIs. It was amazedly found that the co‐PI fibers exhibited higher tensile strength and initial modulus than those of corresponding homo‐PI fibers, reaching tensile strength of 2.2–2.6 GPa, initial modulus of 99.1–113.2 GPa. The results of dynamic mechanical analysis (DMA) indicated co‐PI2 fiber had a positive T_g deviation due to the presence of strong intermolecular hydrogen bonding between benzimidazole‐imide and benzoxazole‐imide units, which maybe lead to the effective stress transfer between benzimidazole‐imide units and benzoxazole‐imide units. In addition, the obtained PI fibers exhibited excellent thermal properties with the 10% weight loss temperatures under N₂ in the range of 574–585°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42001.     

Reduction and cyclization to form poly(benzimidazole amide imide) copolymers

Poly(amide imide) copolymers were synthesized with different molar ratios of 4,4‐diphenylmethane diisocyanate, two types of aromatic dianhydrides (pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐sulfonyl diphthalic anhydride (DSDA)), and a diacid, which was derived from 3,3′‐dinitrobenzidine and isophthaloyl chloride in a previous work. In this study, the copolymers were further reacted with a reducing agent, and the nitro groups in the copolymers were hydrogenated into amine groups. Then, the amine‐group‐containing poly(amide imide) copolymers were cyclized at 180°C to form the poly(benzimidazole imide amide) copolymers in poly(phosphoric acid), which acted as a cyclizing agent. The resultant copolymers were soluble in sulfuric acid and poly(phosphoric acid) at room temperature and in sulfolane or N‐methyl‐2‐pyrrolidone under heating to 100°C with 5% lithium chloride. According to wide‐angle X‐ray diffraction, all the copolymers were amorphous. According to thermal analysis, the glass‐transition temperature ranged from 270 to 322°C, and the 10% weight‐loss temperature ranged from 460 to 541°C in nitrogen and from 441 to 529°C in air. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 378–386, 2004     

Synthesis of thermally stable aromatic poly(imide amide benzimidazole) copolymers

3,3′‐Dinitrobenzidine was first reacted with excess m‐chlorophenyl acid to form a monomer with dicarboxylic acid end groups. Two types of aromatic dianhydrides (Pyromellitic diconhydride (PMDA) and 3,3′,4,4′‐sulfonyl diphthalic anhydride) were also reacted with excess 4,4′‐diphenylmethane diisocyanate to form polyimide prepolymers terminated with isocyanate groups. The prepolymers were further extended with the diacid monomer to form nitro groups containing aromatic poly(imide amide). The nitro groups in these copolymers were hydrogenated to form amine groups and then were cyclized at 180°C to form poly(imide amide benzimidazole) in poly(phosphoric acid), which acted as a cyclization agent. The resultant copolymers were soluble in sulfuric acid and poly(phosphoric acid), in sulfolane under heating to 100°C, and in the polar solvent N‐methyl‐2‐pyrrolidone under heating to 100°C with 5% lithium chloride. According to wide‐angle X‐ray diffraction, all the copolymers were amorphous. According to thermal analysis, the glass‐transition temperatures of the copolymers were 270–322°C. The 10% weight‐loss temperatures were 460–541°C in nitrogen and 441–529°C in air. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1435–1444, 2003     

The evolution of poly(hydroxyamide amic acid) to poly(benzoxazole) via stepwise thermal cyclization: Structural changes and gas transport properties

The thermally induced structure transformation and polymer chain rearrangement of a thermally rearranged (TR) material for gas separation has been explored in this work. A tremendous enhancement as high as 215 folds in CO₂ permeability has been achieved by converting the pristine poly(hydroxyamide amic acid) (PHAA) to the final polybenzoxazole (PBO) via thermal cyclization at 400 °C for 2 h. The evolution of the pristine polymer PHAA derived from 2,2-bis(3-amino-4-hydroxyphenyl)hexafluropropane (BisAPAF) and trimellitic anhydride chloride (TAC) by thermal treatment from 130 °C to 400 °C has been examined by various characterization techniques including elemental analysis, TGA, TGA-IR, DSC, ATR-FTIR, XPS, XRD and Positron Annihilation Lifetime Spectroscopy (PALS). The stepwise cyclization process commences with cyclodehydration followed by cyclodecarboxylation. At the first step, PHAA transforms to poly(imide benzoxazole) (PIBO) up to 300 °C, while at the second step, the final structure of PBO is formed at 400 °C. Following the changes in the cyclization process, gas transport properties also show the stepwise changes. The significant enlargements of polymer inter-chain distance and free volume cavity radius provide the fundamental understanding for the changes of gas transport properties at the molecular level.     

Synthesis and characterization of new cardo poly(ether imide)s derived from 9,9‐bis [4‐(4‐aminophenoxy)phenyl]xanthene

A series of new cardo poly(ether imide)s bearing flexible ether and bulky xanthene pendant groups was prepared from 9,9‐bis[4‐(4‐aminophenoxy)phenyl]xanthene with six commercially available aromatic tetracarboxylic dianhydrides in N,N‐dimethylacetamide (DMAc) via the poly(amic acid) precursors and subsequent thermal or chemical imidization. The intermediate poly(amic acid)s had inherent viscosities between 0.83 and 1.28 dL/g, could be cast from DMAc solutions and thermally converted into transparent, flexible, and tough poly(ether imide) films which were further characterized by X‐ray and mechanical analysis. All of the poly(ether imide)s were amorphous and their films exhibited tensile strengths of 89–108 MPa, elongations at break of 7–9%, and initial moduli of 2.12–2.65 GPa. Three poly(ether imide)s derived from 4,4′‐oxydiphthalic anhydride, 4,4′‐sulfonyldiphthalic anhydride, and 2,2‐bis(3,4‐dicarboxyphenyl))hexafluoropropane anhydride, respectively, exhibited excellent solubility in various solvents such as DMAc, N,N‐dimethylformamide, N‐methyl‐2‐pyrrolidinone, pyridine, and even in tetrahydrofuran at room temperature. The resulting poly(ether imide)s with glass transition temperatures between 286 and 335°C had initial decomposition temperatures above 500°C, 10% weight loss temperatures ranging from 551 to 575°C in nitrogen and 547 to 570°C in air, and char yields of 53–64% at 800°C in nitrogen. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of poly(propylene glycol)‐grafted polyimide precursors and preparation of nanoporous polyimides

A novel approach to prepare a polyimide nanofoam was explored by using a polyimide precursor grafted with a labile poly(propylene glycol) (PPG) oligomer. The PPG‐grafted polyimide precursor, poly((amic acid)‐co‐(amic ester)), was synthesized via partial esterification of poly(amic acid) derived from pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA) with bromo‐terminated poly(propylene glycol) in the presence of K₂CO₃ in hexamethylphosphoramide and N‐methylpyrrolidone. The precursor polymer film was spin‐coated onto a glass substrate, then imidized at 200 °C under nitrogen, and subsequently the PPG graft was decomposed by heating the film at 300 °C for 9 h in air, resulting in the PMDA/ODA polyimide nanofoam. The precursor polymers, polyimides and foamed polyimides were characterized by a variety of techniques including ¹H‐NMR spectroscopy, Fourier‐transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The homogeneously distributed nano‐sized pores of 20–40 nm were observed by transmission electron microscopy (TEM) of the foamed polyimide. Copyright © 2004 Society of Chemical Industry     

Synthesis and properties of poly(ether imide)s derived from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and aromatic ether–diamines

A series of poly(ether imide)s (PEIs) with light colors and good mechanical properties were synthesized from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and various aromatic ether–diamines via a conventional two‐step polymerization technique that included ring‐opening polyaddition at room temperature to poly(amic acid)s (PAAs) followed by thermal imidization. The precursor PAAs had inherent viscosities ranging from 0.71 to 1.19 dL/g and were solution‐cast and thermally cyclodehydrated to flexible and tough PEI films. All of the PEI films were essentially colorless, with ultraviolet–visible absorption cutoff wavelengths between 377 and 385 nm and yellowness index values ranging from 10.5 to 19.9. These PEIs showed high thermal stabilities with glass‐transition temperatures of 206–262°C and decomposition temperatures (at 10% weight loss) higher than 478°C. They also showed low dielectric constants of 3.39–3.72 (at 1 MHz) and low water absorptions below 0.85 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Enhanced solubility of novel poly(benzoxazole)s with a soft linkage and a rigid pendant group

Aromatic poly(benzoxazole)s are a class of rigid‐rod conjugated polymers. However, their poor solubility in organic solvents limits potential applications. Thus, a good method that can address this dilemma is needed, given that existing methods involve models with either poor solubility but good thermal stability or good solubility but poor thermal stability. In this paper we report a novel aromatic poly(benzoxazole) with a soft linkage and a rigid pendant group. Structural characterizations of the polymers via Fourier transform infrared and proton nuclear magnetic resonance spectroscopy reveal the formation of a benzoxazole ring and an imide ring. The introduction of rigid pendant groups improved the solubility and enhanced the thermal stability of the polymer, which was impaired by the incorporation of the soft linkage. Most of these polymers are soluble at room temperature or when heated in dimethyl sulfoxide, N,N‐dimethylformamide or N,N‐dimethylacetamide. Some polymers can even be dissolved in m‐cresol and tetrahydrofuran. A 10% weight loss in these polymers was observed at temperatures over 410 °C. Moreover, the incorporation of the imide pendant group increased the conjugation length of the polymer structural unit and accelerated electron delocalization. Copyright © 2012 Society of Chemical Industry     

Poly(amide imide)s and poly(amide imide) composite membranes by interfacial polymerization

Novel amic acid diamines (AADs) (2‐carboxyterephthalamido‐bis(alkyl or aryl amine)s, H₂N? X? NH(O?)C? C₆H₃(COOH)? C(?O)NH? X? NH₂, where X is were synthesized by reacting trimellitic anhydride chloride with aromatic or aliphatic diamines in dimethylformamide at 5–10 °C. Poly(amide imide)s (PAIs) with an amide to imide ratio of three in the polymer chains were prepared by interfacial polycondensation of the AADs in aqueous alkaline solution with isophthaloyl chloride or terephthaloyl chloride in dichloromethane at ambient temperature to form poly(amide amic acid)s, followed by their subsequent thermal cycloimidization. All of the PAIs were soluble in polar aprotic solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide and N‐methylpyrrolidone, and have inherent viscosities in the range 0.15–0.48 dL g^?1. The polymers were characterized by IR and NMR spectroscopy, TGA and DSC techniques. The PAIs have initial decomposition temperatures in the range 250–460 °C in air, and glass transition temperatures of 128–320 °C, depending upon the structures of the monomers. Composite membranes containing a poly(amide amic acid) and poly(amide imide) barrier layer on the top of a porous polyethersulfone support were prepared by in situ interfacial polymerization of the AADs in aqueous alkaline solution with trimesoyl chloride in hexane, and subsequent curing. The performances of these membranes were evaluated by using aqueous feed solutions containing 2000 ppm NaCl, Na₂SO₄ or CaCl₂. Copyright © 2006 Society of Chemical Industry     

Influence of azobenzene units on imidization kinetic of novel poly(ester amic acid)s and polymers properties before and after cyclodehydration

In this article, the imidization reaction kinetic of novel poly(ester amic acid)s with azobenzene units as side groups was studied by dynamic experiments by means of differential scanning calorimetry. Polymers differ in the number of chromophore moieties in their repeating unit and position in which azobenzene group is attached to the polymer chain. The kinetic parameters of poly(ester amic acid)s conversion to poly(ester imide)s was compared with data calculated for parent polymer, that is, without azobenzene groups. For the first time to our knowledge, the imidization kinetic of polymers with side azobenzene groups was studied. Kinetic parameters, such as the activation energy and frequency factor were estimated with the by Ozawa model [(E(O) and A(O)), respectively] and Kissinger model [(E(K) and A(K), respectively]. The values of activation energy determined with both models were in the range 167.1–198.3 kJ/mol. The lowest activation energy of imidization reaction exhibited polymer in which azobenzene units were placed between amide linkages. Polymers were characterized by FTIR, ¹H‐NMR, X‐ray, and UV–vis methods. The glass transition temperature of resultant poly(ester imide)s was in the range of 217–237°C. The presence of chromophore units slightly decreased T_g and significantly improved their solubility and optical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Processable and colorless fluorinated poly(ether imide)s based on an isopropylidene‐containing bis(ether anhydride) and various aromatic bis(ether amine)s bearing trifluoromethyl groups

A series of novel organosoluble and light‐colored fluorinated poly(ether imide)s (PEIs) ( IV ) having inherent viscosities of 0.43–0.59 dL/g were prepared from 4,4′‐[1,4‐phenylenbis(isopropylidene‐1,4‐phenyleneoxy)]diphthalic anhydride ( I ) and various trifluoromethyl‐substituted aromatic bis(ether amine)s by a standard two‐step process with thermal and chemical imidization of poly(amic acid) precursors. These PEIs showed excellent solubility in many organic solvents and could be solution‐cast into transparent and tough films. These films were essentially colorless, with an UV–visible absorption edge of 361–375 nm and a very low b* value (a yellowness index) of 15.3–17.0. They also showed good thermal stability with glass‐transition temperature of 191–248°C, 10% weight loss temperature in excess of 494°C, and char yields at 800°C in nitrogen more than 39%. The thermally cured PEI films showed good mechanical properties with tensile strengths of 83–96 MPa, elongations at break of 8–11%, and initial moduli of 1.7–2.0 GPa. They possessed lower dielectric constants of 3.25–3.72 (1 MHz). In comparison with the V series nonfluorinated PEIs, the IV series showed better solubility, lower color intensity, and lower dielectric constants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 620–628, 2007     

Synthesis and properties of hydrogen‐bonded poly(amide‐imide) hybrid films

Poly(amide‐imide), PI, hybrid films are prepared by using sol–gel techniques. First, the poly(amide amic acid) with controlled block chain length of 5000 and 10,000 g/mol and uncontrolled chain length are synthesized by condensation reaction with 4,4′‐diaminodiphenyl ether (ODA), 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), trimellitic anhydride chloride (TMAC) and terminated with p‐aminopropyltrimethoxysilane (APrTMOS). And then the imidization reactions of poly (amide amic acid) are proceeded to obtain the poly (amide‐imide) hybrid film. Hybrid films with 5000 g/mol block chain length possess higher storage modulus, lower glass transition temperature and damping intensity comparing to films with 10,000 g/mol block chain length. The addition of TMAC to the poly(amide‐imide) hybrids is due to the increase of toughness and intermolecular hydrogen bonding, which is the average strength of intermolecular bonding and studied by the hydrogen‐bonded fraction (f_bonded), frequency difference (Δν) and shiftment. Meanwhile, PI hybrid films containing more APrTMOS and TMAC content possess higher thermal and mechanical properties. On the other hand, hybrid films with 10,000 g/mol block chain length and more TMAC content have higher gas permeabilities than other films. The degradation temperatures of 5 wt % loss of all hybrid films are all higher than 540°C and increased as the increase of TMAC content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

New,organo‐soluble,thermally stable aromatic polyimides and poly(amide‐imide) based on 2‐[5‐(3,5‐dinitrophenyl)‐1,3, 4‐oxadiazole‐2‐yl]pyridine

New, thermally stable polyimides and a poly(amide‐imide) containing a 1,3,4‐oxadiazole‐2‐pyridyl pendant group based on 2‐[5‐(3,5‐diaminophenyl)‐1,3,4‐oxadiazole‐2‐yl]pyridine were synthesized. The synthesis and characterization of the model compound 2‐{5‐[(3,5‐bistrimellitimido)phenyl]‐1,3,4‐oxadiazole‐2‐yl}pyridine (DIDA) were also investigated, and DIDA was used in the preparation of the poly(amide‐imide) in an ionic liquid, 1‐butyl‐3‐methylimidazolium bromide, as a polymerization solvent. The polymers were characterized by separating and characterizing the poly(amic acid) intermediates using infrared and elemental analyses. The prepared polymers were soluble in polar and aprotic solvents, such as dimethylformamide, dimethylsulfoxide, N‐methyl‐2‐pyrrolidone and dimethylacetamide. Thermal behaviour of the polymers was studied using thermogravimetric analysis and differential scanning calorimetry. The inherent viscosities of the polyimide and poly(amide‐imide) solutions were in the range 0.34–0.85 dL g^?1 (in concentrated sulfuric acid with a concentration of 0.125 g dL^?1 at 25 ± 0.5 °C). The removal of Co(II) from aqueous solutions was performed using one of the polyimides. It was found that this polymer had a maximum adsorption capacity and efficiency at pH = 10.0. Copyright © 2012 Society of Chemical Industry     

Thermally stable and organosoluble cardo binaphthylene based poly(amide imide)s and poly(ester imide)s

A new imide‐containing dicarboxylic acid based on a twisted binaphthylene unit, 2,2′‐bis(N‐trimellitoyl)‐1,1′‐binaphthyl (1), was synthesized from 1,1′‐binaphthyl‐2,2′‐diamine and trimellitic anhydride in glacial acetic acid. The structure of compound 1 was fully characterized with spectroscopic methods and elemental analysis. Series of thermally stable and organosoluble poly(amide imide)s (4a–4d) and poly(ester imide)s (5a–5d) with similar backbones were prepared by the triphenyl phosphite and diphenylchlorophosphate activated direct polycondensation of diimide dicarboxylic acid 1 with various aromatic diamines and diols, respectively. With due attention to the structural similarity of the resulting poly(amide imide)s and poly(ester imide)s, most of the differences between these two block copolyimides could be easily attributed to the presence of alternate amide or ester linkages accompanied by imide groups in the polymer backbone. The ultraviolet maximum wavelength values of the yellowish polymers were determined from their ultraviolet spectra. The crystallinity of these copolyimides was estimated by means of wide‐angle X‐ray diffraction, and the resultant polymers exhibited a nearly amorphous nature, except for the polymers derived from benzidine and 4,4′‐binaphthol. The poly(amide imide)s exhibited excellent solubility in a variety of highly polar aprotic solvents, whereas the poly(ester imide)s showed good solubility in less polar solvents. According to differential scanning calorimetry analyses, polymers 4a–4d and 5a–5d had glass‐transition temperatures between 331 and 357°C and between 318 and 342°C, respectively. The thermal behaviors of the obtained polymers were characterized by thermogravimetric analysis, and the 10% weight loss temperatures of the poly(amide imide)s and poly(ester imide)s were between 579 and 604°C and between 566 and 577°C in nitrogen, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3203–3211, 2006     

Imide-to-benzoxazole rearrangement in ortho substituted poly(4-4'-diphenylene pyromellitimide)s

Summary Ortho substituted poly(4,4'-diphenylene pyromellitimide)s were prepared from pyromellitic dianhydride and 3,3′-dihydroxybenzidine or 3,3′-dimethoxybenzidine. Thermal cyclodehydration of the corresponding poly(amic acid)s, PAA, led to the formation of ortho-hydroxy- or o-methoxy-polyimides, while catalytic imidization in the presence of aliphatic anhydrides was accompanied by acylation of the OH groups resulting in the formation of lateral acetoxy substituents. The direction of the latter reaction was controlled by the acidity of dehydration agents and the use of a catalyst. Imidization in the presence of acetic anhydride and pyridine led to poly[(3,3'-diacetoxy-4,4'-diphenylene)pyromellitimide] and the use of trifluoroacetic anhydride resulted in the formation of the corresponding polyisoimide with ortho-trifluoroacetoxy groups. This polyisoimide was completely soluble in amide solvents above 60°C. The polymers were studied by FTIR spectroscopy, TGA, and WAXS. It was found that ortho substituents such as OH and methoxy groups could react with the imide cycle above 350°C causing its rearrangement to benzoxazole. The formation of notable amounts of benzoxazole was also observed for o-acetoxy polyimides. Received: 20 November 2001/Revised version: 19 March 2002/ Accepted: 19 March 2002     

Thermal and thermo‐oxidative degradation properties of poly(benzimidazole amide imide) copolymers

In this study, 3,3′‐dinitrobenzidine was first reacted with excess isophthaloyl chloride to form a monomer with dicarboxylic acid end groups. Two types of aromatic dianhydride, [viz., pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐sulfonyldiphthalic anhydride (DSDA)] also were reacted with excess 4,4′‐diphenyl‐ methane diisocyanate (MDI) to form polyimide prepolymers terminated with isocyanate groups. The prepolymers were reacted further with the diacid monomer to form a nitro group–containing aromatic poly(amide imide) copolymers. The nitro groups in these copolymers were hydrogenated to form amine groups and cyclized at 180°C to form the poly(benzimidazole amide imide) copolymers in polyphosphoric acid (PPA), which acts as a cyclization agent. From the viscosity measurements, copolymer appeared to be a reasonably high molecular weight. From the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements it was shown that the glass transition temperature of copolymers was in the range of ～270–322°C. The 10% weight loss temperatures were in the range of 460 ～ 541°C in nitrogen and ～441–529°C in air, respectively. The activated energy and the integration parameter of degradation temperature of the copolymers were evaluated with the Doyle‐Ozawa method. It indicated that these copolymers have good thermal and thermo‐oxidative stability with the increase in imide content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2072–2081, 2004     

Pervaporation membranes based on imide‐containing poly(amic acid) and poly(phenylene oxide)

Three imide‐containing poly(amic acids) were synthesized and used for homogeneous and composite membrane preparation. The transport properties of composite membranes consisting of an imide‐containing poly(amic acid) top layer on an asymmetric porous poly(phenylene oxide) support were studied in the pervaporation of aqueous solutions of organic liquids (ethanol, isopropanol, acetone, and ethylacetate) and organic/organic mixtures (ethylacetate/ethanol, methanol/cyclohexane). For most of the aqueous/organic mixtures, the composite membranes exhibited dehydration properties. Dilute aqueous solutions of ethylacetate were an exception. In these solutions, the composite membranes exhibited organophilic properties, high permeability, and selectivity with respect to ethylacetate. In the pervaporation of methanol/cyclohexane mixtures, methanol was removed with very high selectivity. To account for specific features of pervaporation on the composite membranes, the sorption and transport properties of homogeneous membranes prepared from polymers comprising the composite membrane [imide‐containing poly(amic acids) and poly(phenylene oxide)] were studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2361–2368, 2003     

Synthesis and properties of PMR type poly(benzimidazopyrrolone‐imide)s

PMR type poly(benzimidazopyrrolone‐imide) or poly(pyrrolone‐imide) (PPI) matrix resin was synthesized using the diethyl ester of 4,4′‐(hexafluoroisopropylidene)diphthalic acid (6FDE), 3,3′‐diaminobenzidine, para‐phenylenediamine, and monoethyl ester of cis‐5‐norbornene‐endo‐2,3‐dicarboxylic acid (NE) in anhydrous ethyl alcohol with N‐methylpyrrolidone. The homogeneous matrix resin solution (40–50% solid) was stable for a storage period of 2 weeks and showed good adhesion with carbon fibers, which ensured production of prepregs. The chemical and thermal processes in the polycondensation of the monomeric reactant mixture were monitored by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, etc. Thermosetting PPI as well as short carbon fiber‐reinforced polymer composites was accomplished at optimal thermal curing conditions. The polymer materials, after postcuring, showed excellent thermal stability, with an initial decomposition temperature > 540°C. Results of MDA experiments indicate that the materials showed > 70–80% retention of the storage modulus at 400°C and glass transition temperatures as high as 440–451°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1600–1608, 2001     

Copolyimides new polybenzoxazinone-imides

New polybenzoxazinone-imides have been synthesized by cyclopolycondensation reaction of 4,4′-diaminodiphenylmethane-3,3′-dicarboxylic acid with diacid chlorides containing preformed imide rings. The low temperature solution polycondensation technique, used in these experiments, afforded poly(amic acids) of high molecular weight in the first step, which subsequently underwent thermal cyclodehydration at 200–300°C to give polybenzoxazinone-imides in the second step. The obtained polymers have been characterized by IR absorption, elemental and thermogravimetric analyses. From 10% polymer solution flexible and transparent films have been cast with good mechanical and insulating properties.