Synthesis and characterization of soluble polyimides derived from 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride

A novel bis(ether anhydride) monomer, 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride, was synthesized from the nitro displacement of 4‐nitrophthalonitrile by the phenoxide ion of 2′,5′‐dihydroxy‐p‐terphenyl, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and cyclodehydration of the resulting bis(ether diacid). A series of new poly(ether imide)s bearing laterally attached p‐terphenyl groups were prepared from the bis(ether anhydride) with various aromatic diamines via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by thermal or chemical imidization to the poly(ether imide)s. The inherent viscosities of the poly(amic acid) precursors were in the range of 0.62–1.26 dL/g. Most of the poly(ether imide)s obtained from both routes were soluble in polar organic solvents, such as N,N‐dimethylacetamide. All the poly(ether imide)s could afford transparent, flexible, and strong films with high tensile strengths. The glass‐transition temperatures of these poly(ether imide)s were recorded as between 214 and 276 °C by DSC. The softening temperatures of all the poly(ether imide) films stayed in the 207–265 °C range according to thermomechanical analysis. For all the polymers significant decomposition did not occur below 500 °C in nitrogen or air atmosphere. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1008–1017, 2004     

Synthesis and characterization of aromatic poly(ether sulfone imide)s derived from sulfonyl bis(ether anhydride)s and aromatic diamines

Two sulfonyl group-containing bis(ether anhydride)s, 4,4′-[sulfonylbis(1,4-phenylene)dioxy]diphthalic anhydride ( IV ) and 4,4′-[sulfonylbis(2,6-dimethyl-1,4-phenylene)dioxy]diphthalic anhydride (Me- IV ), were prepared in three steps starting from the nucleophilic nitrodisplacement reaction of the bisphenolate ions of 4,4′-sulfonyldiphenol and 4,4′-sulfonylbis(2,6-dimethylphenol) with 4-nitrophthalonitrile in N,N-dimethylformamide (DMF). High-molar-mass aromatic poly(ether sulfone imide)s were synthesized via a conventional two-stage procedure from the bis(ether anhydride)s and various aromatic diamines. The inherent viscosities of the intermediate poly(ether sulfone amic acid)s were in the ranges of 0.30–0.47 dL/g for those from IV and 0.64–1.34 dL/g for those from Me- IV. After thermal imidization, the resulting two series of poly(ether sulfone imide)s had inherent viscosities of 0.25–0.49 and 0.39–1.19 dL/g, respectively. Most of the polyimides showed distinct glass transitions on their differential scanning calorimetry (DSC) curves, and their glass transition temperatures (T_g) were recorded between 223–253 and 252–288°C, respectively. The results of thermogravimetry (TG) revealed that all the poly(ether sulfone imide)s showed no significant weight loss before 400°C. The methyl-substituted polymers showed higher T_g's but lower initial decomposition temperatures and less solubility compared to the corresponding unsubstituted polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1649–1656, 1998     

Synthesis and properties of poly(ether imide)s derived from 2,6-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride and aromatic diamines

A new naphthalene unit-containing bis(ether anhydride), 2,6-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride, was synthesized in three steps starting from the nucleophilic nitrodisplacement reaction of 2,6-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). High-molar-mass aromatic poly(ether imide)s were prepared using a conventional two-step polymerization process from the bis(ether anhydride) and various aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0.65–2.03 dL/g. The films of poly(ether imide)s derived from two rigid diamines, i.e. p-phenylenediamine and benzidine, crystallized during the thermal imidization process. The other poly(ether imide)s belonged to amorphous materials and could be fabricated into transparent, flexible, and tough films. These aromatic poly(ether imide) films had yield strengths of 104–131 MPa, tensile strengths of 102–153 MPa, elongation to break of 8–87%, and initial moduli of 1.6–3.2 GPa. The glass transition temperatures (T_g's) of poly(ether imide)s were recorded in the range of 220–277°C depending on the nature of the diamine moiety. All polymers were stable up to 500°C, with 10% weight loss being recorded above 550°C in both air and nitrogen atmospheres. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1657–1665, 1998     

Synthesis and properties of poly(ether imide)s based on a benzonorbornane bis(ether anhydride)

A novel bis(ether anhydride) monomer, 3,6‐bis(3,4‐dicarboxyphenoxy)benzonorbornane dianhydride, was synthesized from the nitro displacement of 4‐nitrophthalonitrile with 3,6‐dihydroxybenzonorbornane in the presence of potassium carbonate, followed by the alkaline hydrolysis of the intermediate bis(ether dinitrile) and the cyclodehydration of the resulting bis(ether diacid). A series of poly(ether imide)s bearing pendant norbornane groups were prepared from the bis(ether anhydride) with various aromatic diamines via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by thermal imidization to the poly(ether imide)s. The inherent viscosities of the poly(amic acid) precursors were 0.81–1.81 dL/g. The poly(ether imide) with m‐phenylenediamine as a diamine showed good organosolubility. Most of the cast poly(ether imide) films have had high tensile strengths and moduli. The glass‐transition temperatures of these poly(ether imide)s, except for those from rigid p‐phenylenediamine and benzidine, were recorded between 211 and 246 °C by differential scanning calorimetry. The softening temperatures of all the poly(ether imide) films stayed within 210–330 °C according to thermomechanical analysis. No polymers showed significant decomposition before 500 °C in a nitrogen or air atmosphere. A comparative study of the properties with the corresponding poly(ether imide)s without pendant substituents was also made. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1712–1725, 2002     

Blend of polyimide having internal acetylene units and oligoimide end-capped with biphenylenes

A N-Methylpyrrolidone (NMP) solution of polymic acid having internal acetylene units in the backbone was mixed with a NMP solution of oligomeric amic acid end-capped with biphenylenes to afford a miscible solution. The viscosity of polymic acid solution lowered considerably by the addition of oligomers, which could lead to improved processability. The amic acid mixture was thermally or chemically cyclized to give a blend of internal-reactive polymide and end-reactive oligoimide. Films of imide blends were easily prepared by casting solutions of the amic acid blends followed by imidization. The imide blends were thermally cured at 400°C for 10 min to give cross-linked polyimides that showed excellent thermal stability as confirmed by DSC, TGA, TMA, and viscoelastic analyses of the cured films. A selective co-crosslinking reaction between biphenylene in the oligomide and acetylene in the polyimide to give phenanthrene linkage is supposed to be the cause of the high thermal stability.     

Synthesis and characterization of new cardo polyimides prepared from 5,5-Bis[4-(4-aminophenoxy)phenyl]-4,7-methanohexahydroindane

A new cardo diamine monomer, 5,5-bis[4-(4-aminophenoxy)phenyl]-4,7-methanohexahydroindane (II), was prepared in two steps with high yield. The monomer was reacted with six different aromatic tetracarboxylic dianhydrides in N,N-dimethylacetamide (DMAc) to obtain the corresponding cardo polyimides via the poly(amic acid) precursors and thermal or chemical imidization. All the poly(amic acid)s could be cast from their DMAc solutions and thermally converted into transparent, flexible, and tough polyimide films which were further characterized by x-ray and mechanical analysis. All of the polymers were amorphous and the polyimide films had a tensile strength range of 89–123 MPa, an elongation at break range of 6–10%, and a tensile modulus range of 1.9–2.5 GPa. Polymers V_c, V_e, and V_f exhibited good solubility in a variety of solvents such as N-methyl-2-pyrrolidinone (NMP), DMAc, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, γ-butyrolactone, and even in tetrahydrofuran and chloroform. These polyimides showed glass-transition temperatures between 274 and 299°C and decomposition temperatures at 10% mass loss temperatures ranging from 490 to 521°C and 499 to 532°C in nitrogen and air atmospheres, respectively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2815–2821, 1999     

Synthesis and evaluation of novel polyimides derived from spirobichroman diether anhydride

A spirobichroman structure-containing diether anhydride (SBCDA), 6,6′-bis(3,4-dicarboxyphenoxy)-4,4,4′,4′,7,7′-hexamethyl-2,2′-spirobichroman dianhydride, was prepared by the nucleophilic nitrodisplacement of 4-nitrophthalonitrile with the phenolate ion of 6,6′-dihydroxy-4,4,4′,4′,7,7′-hexamethyl-2,2′-spirobichroman, followed by alkaline hydrolysis of the intermediate tetranitrile and dehydration of the resulting tetraacid. A series of high molecular weight poly(ether imide)s with inherent viscosities between 0.45 and 1.28 dL/g were synthesized from SBCDA and various aromatic diamines via a conventional two-stage procedure that included ring-opening polyaddition in N,N-dimethylacetamide (DMAc) to give poly(amic acid)s, followed by thermal cyclization to poly(ether imide)s. The intermediate poly(amic acid)s had inherent viscosities of 0.70–1.50 dL/g. Except for the poly(ether imide) obtained from p-phenylenediamine, the other poly(ether imide)s were soluble in various organic solvents and could be solution-cast into transparent, flexible, and tough films. These poly(ether imide)s had glass transition temperatures in the range 175–262°C and showed no significant decomposition below 420°C, with 10% weight loss being recorded above 446°C in nitrogen or air. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2801–2809, 1997     

Synthesis and properties of poly(ether imide)s derived from 2,7-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride and various aromatic diamines

A naphthalene unit-containing bis(ether anhydride), 2,7-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride, was prepared in three steps starting from the nucleophilic nitrodisplacement reaction of 2,7-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). High-molar-mass aromatic poly(ether imide)s were synthesized using a conventional two-stage polymerization process from the bis(ether anhydride) and ten aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0.95–2.67 dL/g. The films of poly(ether imide)s derived from two rigid diamines, that is, p-phenylenediamine and benzidine, crystallized and embrittled during the thermal imidization process. The other poly(ether imide)s belonged to amorphous materials and could be fabricated into transparent, flexible, and tough films. These poly(ether imide) films had yield strengths of 91–115 MPa, tensile strengths of 89–136 MPa, elongation to break of 11–45%, and initial moduli of 1.7–2.2 GPa. The T_gs of poly(ether imide)s were recorded in the range of 222–256°C depending on the nature of the diamine moiety. All polymers were thermally stable up to 500°C, with 10% weight loss being recorded above 540°C in air and nitrogen atmospheres. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2281–2287, 1997     

Thermal and optical properties of some phosphorus‐containing poly(1,3,4‐oxadiazole‐ester‐imide)s

A series of phosphorus‐containing poly(1,3,4‐oxadiazole‐ester‐imide)s was prepared by polycondensation reaction of an aromatic dianhydride, namely 1,4‐[2‐(6‐oxido‐6H‐dibenz<c,e><1,2>oxaphosphorin‐6‐yl)]‐naphthalene‐bis(trimellitate)dianhydride, with different aromatic diamines containing 1,3,4‐oxadiazole ring. A solution imidization procedure was used to convert quantitatively the poly(amic acid) intermediates to the corresponding polyimides. The chemical structures of the monomers and polymers were confirmed by Fourier transform infrared, ¹H NMR and ³¹P NMR spectroscopy. The polymers were easily soluble in polar solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide and tetrahydrofuran. They exhibited good thermal properties having the decomposition temperature above 380°C and the glass transition temperature in the range of 201–232°C. Due to the presence of phosphorus the polymers gave high char yield in termogravimetric analysis, hence good flame retardant properties. Optical properties were analyzed in solution by using UV–vis and photoluminescence spectroscopy. Solutions of the polymers in NMP exhibited photoluminescence in the blue region. Copyright © 2010 John Wiley & Sons, Ltd.     

Cyclopolycondensation. XIII. New synthetic route to fully aromatic poly(heterocyclic imides) with alternating repeating units

Fully aromatic poly(heterocyclic imides) of high molecular weight were prepared by the cyclopolycondensation reactions of aromatic diamines with new monomer adducts prepared by condensing orthodisubstituted aromatic diamines with chloroformyl phthalic anhydrides. The low-temperature solution polymerization techniques yielded tractable poly(amic acid), which was converted to poly(heterocyclic imides) by heat treatment to effect cyclodehydration at 250–400°C under reduced pressure. In this way, the polyaromatic imideheterocycles such as poly(benzoxazinone imides), poly(benzoxazole imides), poly(benzimidazole imides) and poly(benzothiazole imides) were prepared, which have excellent processability and thermal stability both in nitrogen and in air. The poly(amic acids) are soluble in such organic polar solvents as N,N-dimethyl-acetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and the films can be cast from the polymer solution of poly(amic acids) (η_inh = 0.8–1.8). The film is made tough by being heated in nitrogen or under reduced pressure to effect cyclodehydration at 300–400°C. The polymerization was carried out by first isolating the monomer adducts, followed by polymerization with aromatic diamines. On subsequently being heated, the open-chain precursor, poly(amic acid), undergoes cyclodehydration along the polymer chain, giving the thermally stable ordered copolymers of the corresponding heterocyclic imide structure.     

Synthesis and characterization of poly(aryl amide imide)s derived from diphenyltrimellitic anhydride

The synthesis and characterization of a series of novel poly(aryl amide imide)s based on diphenyltrimellitic anhydride are described. The poly(aryl amide imide)s, having inherent viscosities of 0.39–1.43 dL/g in N-methyl-2-pyrrolidinone at 30°C, were prepared by polymerization with aromatic diamines in N,N-dimethylacetamide and subsequent chemical imidization. All the polymers were amorphous, readily soluble in aprotic polar solvents such as DMAC, NMP, dimethylsulfoxide, N,N-dimethylformamide, and m-cresol, and could be cast to form flexible and tough films. The glass transition temperatures were in the range of 284–366°C, and the temperatures for 5% weight loss in nitrogen were above 468°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4541–4545, 1999     

Polyimide containing internal acetylene units linked para to the aromatic ring

4,4′-Diaminodiphenylacetylene (p-intA) was reacted with 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and pyromellitic dianhydride (PMDA) in N-methyl-2-pyrrolidone (NMP) to give poly(amic acid) solution of moderate to high viscosity. Thermal imidization gave polyimide having acetylene units that are linked para to the aromatic connecting unit. Polyimide having acetylene units that are linked meta to the aromatic connecting unit also was prepared utilizing 3,3′-diaminodiphenylacetylene (m-intA) for comparison. The crosslinking behavior of the acetylene units was observed with DSC. Exotherm due to the crosslinking of the para-linked acetylene units appeared at ca. 340 to 380°C depending on the structure of polyimide, whereas meta-linked acetylene units appeared at lower temperature as 340–350°C. After thermal treatment at high temperature such as 350 or 400°C, the amount of the exotherm became smaller and finally disappeared on DSC, confirming the progress of crosslinking. Dynamic mechanical properties of the polyimide films show that glass transition temperature increased with higher heat treatment, also confirming the progress of crosslinking. Tensile properties of the polyimide films showed that rigid polyimide films consisting of p-intA with BPDA or PMDA have considerably higher modulus than those consisting of m-intA. Cold-drawing of the poly(amic acid) followed by imidization gave much higher modulus in the case of rigid polyimide. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2395–2402, 1997     

Synthesis and physical properties of N-substituted polyimides based on imidazole

AB-type monomers based on imidazole for the preparation of polyimides were synthesized by carrying out a substitution at the 1-position of 2-amino-4,5-dicyanoimidazole, followed by hydrolysis. Thus, pendant groups such as hexyl and 2,4-dinitrophenyl as an aliphatic long chain and an electron-withdrawing group, respectively, were introduced at the 1-position of the imidazole monomer. A solid-state polymerization was employed to prepare the poly(imidazoleimide)s in the form of a film from poly(imidazoleamic acid chloride)s by heating up to 180–200°C. The carbonyl stretching peaks of the imide ring appear at 1808 (sym) cm^?1 and 1756 (antisym) cm^?1. The effects of monomer structure on reactivity and the degree of imidization were investigated by comparing the viscosity of the resultant polymers and intensity of carbonyl peak at 1808 cm^?1. The difference in the hydrolysis rate between polyimides having short or long aliphatic pendant groups at the 1-position was observed using FT-IR. The inherent viscosity of the N-hexyl polyimide was 1.26 dL/g in N-methyl pyrrolidinone (NMP) and 0.22 dL/g in the case of N-2,4-dinitrophenyl poly(amic acid) in methanesulfonic acid at 30°C. The structural, physical, and material properties of the polyimides were characterized by infrared, nuclear magnetic resonance, luminescence, viscosimetric methods, differential scanning calorimetry, thermogravimetric analysis, optical microscopy, and wide angle x-ray scattering. Solution properties were also investigated by monitoring the viscosity as a function of time at 30°C. Luminescence spectroscopy of the poly(1-methyl imidazole imide) and poly(1-methyl imidazoleamic acid) films shows an emission band centered at 535 and 505 nm, respectively. Thermal properties are described comparing the weight loss and decomposition temperature as a function of the polymer structure and the degree of imidization. © 1993 John Wiley & Sons, Inc.     

Synthesis,Characterization and Thermal Properties of Imide-Containing Phthalonitrile Polymers

A series of novel imide-containing phthalonitrile polymers with flexible aryl ether units have been synthesized and characterized. Bisphenol monomers were synthesized by a multi-step synthesis involving a condensation reaction between aromatic aldehydes and 2,6-dimethyl phenol, respectively. The bisphenols obtained were reacted with 4-nitrophthalonitrile to form aryl ether linkage containing bisphthalonitriles. These products were hydrolyzed to tetra carboxylic acid, which were subsequently converted into corresponding dianhydrides. The obtained dianhydrides were reacted with synthesized 4-(4′-aminophenoxy) phthalonitrile by thermal imidization leading to the formation of imide-containing phthalonitrile monomers. The synthesized monomers were cured with 3.5 wt% of aromatic diamine, 4,4′-diaminodiphenylsulphone(DDS). The structure and properties of all compounds synthesized were confirmed by using elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR, DSC, TGA and rheometric studies. The cure temperatures are found to be in the range of 283–302°C, the temperature of 5% and 10% weight loss from TGA are in the range of 433–492°C in N₂ and 424–478°C in air, char yield at 800°C is 40–51%.     

Synthesis and properties of new adamantane‐based poly(ether imide)s

A new adamantane‐based bis(ether anhydride), 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]adamantane dianhydride, was prepared in three steps starting from nitrodisplacement of 4‐nitrophthalonitrile with the potassium phenolate of 2,2‐bis(4‐hydroxyphenyl)adamantane. A series of adamantane‐containing poly(ether imide)s were prepared from the adamantane‐based bis(ether anhydride) and aromatic diamines by a conventional two‐stage synthesis in which the poly(ether amic acid)s obtained in the first stage were heated stage‐by‐stage at 150–270°C to give the poly(ether imide)s. The intermediate poly(ether amic acid)s had inherent viscosities between 0.56 and 1.92 dL/g. Except for those from p‐phenylenediamine, m‐phenylenediamine, and benzidine, all the poly(ether amic acid) films could be thermally converted into transparent, flexible, and tough poly(ether imide) films. All the poly(ether imide)s showed limited solubility in organic solvents, although they were amorphous in nature as evidenced by X‐ray diffractograms. Glass transition temperatures of these poly(ether imide)s were recorded in the range of 242–317°C by differential scanning calorimetry and of 270–322°C by dynamic mechanical analysis. They exhibited high resistance to thermal degrdation, with 10% weight loss temperatures being recorded between 514–538°C in nitrogen and 511–527°C in air. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1619–1628, 1999     

Synthesis and properties of new polyimides derived from 1,5-bis(4-aminophenoxy)naphthalene and aromatic tetracarboxylic dianhydrides

Novel aromatic polyimides containing bis(phenoxy)naphthalene units were synthesized from 1,5-bis(4-aminophenoxy)naphthalene (APN) and various aromatic tetracarboxylic dianhydrides by the usual two-step procedure that included ring-opening polyaddition in a polar solvent such as N,N-dimethylacetamide (DMAc) to give poly(amic acid)s, followed by cyclodehydration to polyimides. The poly(amic acid)s had inherent viscosities between 0.72 and 1.94 dL/g, depending on the tetracarboxylic dianhydrides used. Excepting the polyimide IVb obtained from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), all other polyimides formed brown, flexible, and tough films by casting from the poly(amic acid) solutions. The polyimide synthesized from BPDA was characterized as semicrystalline, whereas the other polyimides showed amorphous patterns as shown by the x-ray diffraction studies. Tensile strength, initial moduli, and elongation at break of the APN-based polyimide films ranged from 105–135 MPa, 1.92–2.50 GPa, and 6–7%, respectively. These polyimides had glass transition temperatures between 228 and 317°C. Thermal analyses indicated that these polymers were fairly stable, and the 10% weight loss temperatures by TGA were recorded in the range of 543–574°C in nitrogen and 540–566°C in air atmosphere, respectively. © 1993 John Wiley & Sons, Inc.     

Synthesis and properties of poly(arylene ether imide ketone)s

Poly(arylene ether ketone)s containing imide units were prepared by the aromatic nucleophilic displacement reaction of the potassium salts of bisphenols with bis(4-fluorobenzoyl)phthalimides in N-methyl-2-pyrrolidone at elevated temperature. The polymers having inherent viscosities of 0.34–0.77 dL/g were obtained in 2 h. The polymers exhibited glass transition temperatures ranging from 216 to 268°C and decomposition temperatures (5% weight loss under air atmosphere) ranging from 450–570°C mainly depending on the bisphenols used in the polymer synthesis. The isothermal TGA measurements (400°C under air or nitrogen atmosphere) revealed that the 4,4'-biphenol- and hydroquinone-based poly(arylene ether ketone imide)s belong to a superior class of heat resistant polymers. The mechanical properties of these polymers are also described. © 1994 John Wiley & Sons, Inc.     

Kinetic study of low‐temperature imidization of poly(amic acid)s and preparation of colorless,transparent polyimide films

Conventional synthesis of polyimides includes high‐temperature (160–350 °C) imidization of poly(amic acid)s. In the present work, imidization has been carried out at much lower temperatures (40–160 °C). 1,2,4,5,‐cyclohexanetetracarboxylic dianhydride (HPMDA) or pyromellitic dianhydride (PMDA) was polymerized with an aromatic diamine, 4,4′‐diaminodiphenylmethane (DDPM), to give poly(amic acid)s, which were then imidized chemically. Imidization was more than 90% complete even at the very low imidization temperature of 40 °C. It was found that the imidization occurs in two steps: an initial rapid cyclization and a subsequent slower cyclization. The activation energy for the rapid process was determined to be 4.3 kJ/mol, and that of the slower process, 4.8 kJ/mol. As the imidization temperature decreases, the transmittance of the resulting polyimides tends to gradually increase, the cutoff wavelength decreases and the color becomes pale. A partially aliphatic polyimide based on HPMDA and DDPM prepared at 40 °C yielded thin films that were highly transparent and colorless, and had good flexibility, solubility and thermal stability. The polyimide films prepared in this study may be good candidates for flexible, transparent plastic substrates in the display industry. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1593–1602     

Synthesis,characterization, and crystallization of thermoplastic aromatic semi‐crystalline poly(ester‐imide)s based on bis(trimellitic acid anhydride) phenyl ester

A high molecular weight aromatic homopoly(ester‐imide) (homoPEI) was synthesized from homopoly(ester‐amic acids) (homoPEAA), which was obtained from the reaction of bis(trimellitic acid anhydride) phenyl ester (BTAH) with 4‐4'‐oxydianiline ether (ODA). This homoPEI was melt‐processable semi‐crystalline polymer and displayed dual endothermic transitions which were attributed to the different levels of crystal perfection and size in the crystal structures. Four high molecular weight aromatic copoly(ester‐imide)s (coPEIs) were synthesized via copoly(ester‐amic acids)s (coPEAA) from the reaction of 4, 4'‐oxydiphthalic anhydride (ODPA) and BTAH with ODA. The molar percentage of BTAH varied from 10 to 40%. When the molar percentages of BTAH were 30 and 40%, the resulting two coPEIs were crystallinable and their melting temperatures were 361°C and 356/371°C, respectively. Differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) results indicated that the crystal structures included short segments of BTAH/ODA and ODPA/ODA. The initial crystallization of the two coPEIs took place during imidization process. Thermogravimetric (TA) and mechanical analysis confirmed that both homoPEI and coPEIs showed almost no weight loss until 400°C in N₂ and good mechanical properties. Copyright © 2009 John Wiley & Sons, Ltd.     

New organosoluble polyimides with low dielectric constants derived from bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl] diphenylmethylene

A new kink diamine with trifluoromethyl group on either side, bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]diphenylmethane (BTFAPDM) , was reacted with various aromatic dianhydrides to prepare polyimides via poly (amic acid) precursors followed by thermal or chemical imidization. Polyimides were prepared using 3,3′, 4,4′-biphenyltetracarboxylic dianhydride(1), 4,4′-oxydiphthalic anhydride(2), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (3), 4,4′-sulfonyldiphthalic anhydride(4), and 4,4′-hexafluoroisopropylidene-diphathalic anhydride(5). The fluoro-polyimides exhibited low dielectric constants between 2.46 and 2.98, light color, and excellent high solubility. They exhibited glass transition temperatures between 227 and 253°C, and possessed a coefficient of thermal expansion (CTE) of 60-88 ppm/°C. Polymers PI-2, PI-3, PI-4, PI-5 showed excellent solubility in the organic solvents: N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridkie and tetrahydrofuran (THF). Inherent viscosity of the polyimides were found to range between 0.58 and 0.72 dLg-1. Thermogravimetric analysis of the polyimides revealed a high thermal stability decomposition temperature in excess of 500°C in nitrogen. Temperature at 10 % weight loss was found to be in the range 506-563°C and 498-557°C in nitrogen and air, respectively. The polyimide films had a tensile strength in the range 75-87 MPa; tensile modulus, 1.5-2.2 GPa; and elongation at break, 6-7%.