Synthesis and characterization of thianthrene-containing poly(benzoxazole)s

New thioether- and thianthrene-containing poly(benzoxazole)s (PBOs) were synthesized from 4,4′-thiobis[3-chlorobenzoic acid] and thianthrene-2,7- and -2,8-dicarbonyl chlorides with commercially available bis-o-aminophenols. Polymers were prepared via solution polycondensation in poly(phosphoric acid) at 90–200°C. Transparent PBO films were cast directly from polymerization mixtures or m-cresol. The films were flexible and tough. Non-fluorinated PBOs were soluble only in strong acids and AlCl₃/NO₂R systems by forming complexes with the benzoxazole heterocycle Glass transition temperatures ranged from 298–450°C, and thermogravimetric analysis showed good thermal stabilities in both air and nitrogen atmospheres. © 1995 John Wiley & Sons, Inc.     

Poly(arylene sulfide)s via nucleophilic aromatic substitution reactions of halogenated pyromellitic diimides

Nucleophilic aromatic substitution (SNAr) reactions are exploited to prepare poly(arylene sulfide)s (PAS's) via the reaction of bis-thiolates and dibrominated pyromellitic diimide (PMDI) derivatives. Small-molecule model studies reveal the reaction is well-defined and proceeds in quantitative yield in practical times at room temperature. Variation in comonomer feed ratios allowed some control over target polymer molecular weights in the step polymerization, but control was likely limited by the relatively poor polymer solubility in the dipolar aprotic solvents typically employed to promote SNAr reactions. One substitution pattern produces a steric “pocket” around the PMDI units, inducing a peculiar solubility trend in halogenated solvents; that is, greatly reduced solubility in CHCl₃ relative to CH₂Cl₂ and C₂H₂Cl₄. One example small-molecule readily dissolves in CHCl₃ at room temperature, then rapidly grows poorly soluble crystals revealed by single-crystal XRD to contain CHCl₃ molecules in the steric pockets. Finally, the recently demonstrated depolymerization of phthalonitrile-based PAS's via ipso substitution with monothiolates as chain scission agents yields quantitative molecular weight reduction to monomeric species from the polymers reported here.     

Synthesis and characterization of fluorinated poly(amide imide)s derived from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and aromatic diamines

A series of fluorinated poly(amide imide)s were prepared from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and various aromatic diamines [3,3′,5,5′‐tetramethyl‐4,4′‐diaminediphenylmethane, α,α‐bis(4‐amino‐3,5‐dimethyl phenyl)‐3′‐trifluoromethylphenylmethane, 1,4‐bis(4′‐amino‐2′‐trifluoromethylphenoxy)benzene, 4‐(3′‐trifluoromethylphenyl)‐2,6‐bis(3′‐aminophenyl)pyridine, and 1,1‐bis(4′‐aminophenyl)‐1‐(3′‐trifluoromethylphenyl)‐2,2,2‐trifluoroethane]. The fluorinated poly(amide imide)s, prepared by a one‐step polycondensation procedure, had good solubility both in strong aprotic solvents, such as N‐methyl‐2‐pyrrolidinone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and cyclopentanone, and in common organic solvents, such as tetrahydrofuran and m‐cresol. Strong and flexible polymer films with tensile strengths of 84–99 MPa and ultimate elongation values of 6–9% were prepared by the casting of polymer solutions onto glass substrates, followed by thermal baking. The poly(amide imide) films exhibited high thermal stability, with glass‐transition temperatures of 257–266 °C and initial thermal decomposition temperatures of greater than 540 °C. The polymer films also had good dielectric properties, with dielectric constants of 3.26–3.52 and dissipation factors of 3.0–7.7 × 10^?3, and acceptable electrical insulating properties. The balance of excellent solubility and thermal stability associated with good mechanical and electrical properties made the poly(amide imide)s potential candidates for practical applications in the microelectronics industry and other related fields. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1831–1840, 2003     

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.     

Thermal behavior of aromatic polyamic acids and polyimides containing oxadiazole rings

Two aromatic polyimides and the corresponding poly(amic acid)s, with oxadiazole and para/meta phenoxyphenylene rings in the backbone, were synthesized and the structure — thermal properties correlation was followed by dynamic mechanical analysis. Concerning the poly(amic acid)s, the glass transition domain was emphasized only for the compound with meta-oriented rings because the process of imidization takes place with increasing temperature. A multiplex experiment was performed to calculate the activation energy of the transition localized under 200°C. Consecutive heating-cooling-heating cycles were accomplished. All phenomena are discussed by cross-examination of the storage modulus (E′), loss modulus (E″) and loss factor tanδ variation with temperature.     

Assessment of amination reactions via nucleophilic aromatic substitution using conventional and eco-friendly energies

The efficiency of conventional heating energy source compared with Infrared (IR), Ultrasound (US), Microwave and the simultaneous combination US–IR eco-friendly approaches for preparation of new N-(5-R¹ _-amino-2-nitrophenyl)acetamides and 5-R¹-amino-2-nitroaniline by Nucleophilic Aromatic Substitution (S_NAr) via addition–elimination reactions on the halogens F, Cl, Br, I, employing amines as nucleophiles were explored. Moreover, phenyldiazenyl derivatives in good yields by an oxidative one-pot S_NAr-based amination reaction from an unusual oxidation of 2-phenylhydrazinyl derivatives in DMSO was prepared.     

A new class of aromatic poly(ether-ketone benzoxazole) copolymers by nucleophilic polycondensation: Synthesis and properties

A number of difluorophenyl benzoxazole (DB) monomers and 4,4′-difluorobenzophenone (DFB) were subjected to fluoro-displacement with two different phenoxides in a polar aprotic solvent. A series of novel poly(ether-ketone benzoxazole) copolymers (PAEKBOs) were more readily prepared, in which the generation of aryl-ether linkages was the copolymer forming reaction. The effects of monomer structure and polymerization conditions on the polymerization results and polymer solubility were analyzed. Copolymers 1, 2-X, 4 and 6 were obtained with high molecular weight. Copolymers 2-X and 4 showed organic solubility, especially the copolymers 2-X could dissolve in many usual organic solvents at the solid concentration of up to 20 wt%. TGA and DSC measurements confirmed that the copolymers 2-X, 4 and 6 were thermally stable up to 500 °C, and showed single enhanced T_gs and an amorphous morphology. The copolymers behaved in many respects as engineering thermoplastics. The properties and the processability of several members of the PAEKBOs offer the prospect of being candidates to substitute poly(ether-ether-ketone) (PEEK) using in a wider usage temperature range and being high performance materials for many applications as films, coatings for optical and electronic devices and gas separation membranes.     

Preparation of poly(ether ketone)s derived from 2,5‐furandicarboxylic acid via nucleophilic aromatic substitution polymerization

From the viewpoint of the suppression of the petroleum consumption, aromatic poly(ether ketone)s (PEKs) were prepared by the nucleophilic aromatic substitution polymerization of 2,5‐bis(4‐fluorobenzoyl)furan (BFBF) synthesized from biomass and aromatic bisphenols. The model reaction of BFBF and p‐methoxyphenol revealed that BFBF possessed enough reactivity for the nucleophilic aromatic substitution reactions. The polymerizations of BFBF and aromatic bisphenols afforded high molecular weight polymers with good yields in N‐methylpyrrolidone and diphenyl sulfone for several hours. The longer polymerization time brought about the formation of insoluble parts in any solvents and reduction of molecular weight. The obtained PEKs were thermoplastics and exhibited good thermal stability, mechanical properties, and chemical resistance comparable to common high‐performance polymers. The thermal properties were tunable with the structure of bisphenols. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3094–3101     

Synthesis and properties of fluorinated polyimides. 1. Derived from novel 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl

A new diamine monomer, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl (ATFT) was synthesized that led to a number of novel fluorinated polyimides by solution as well as thermal imidization routes when reacted with different commercially available dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), or 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides ATFT/BTDA and ATFT/6FDA derived from both routes were soluble in several organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide. The polyimide ATFT/PMDA was only soluble in N‐methylpyrollidone. The polyimide films had low water absorption of 0.3–0.7%, low dielectric constants of 2.72–3.3 at 1 Hz, refractive indices of 1.594–1.647 at 589.3 nm, and optical transparency >85%. These polyimides showed very high thermal stability with decomposition temperatures (5% weight loss) up to 532 °C in air and good isothermal stability; only 7% weight loss occurred at 400 °C after 7 h, and less than 0.6% weight loss was observed at 315 °C for 5 h. Transparent thin films of these polyimides exhibited tensile strengths up to 112 MPa, a modulus of elasticity up to 3.05 GPa, and elongation at break up to 21% depending on the repeating unit structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1016–1027, 2002     

Fluoride‐terminated hyperbranched poly(arylene ether phosphine oxide)s via nucleophilic aromatic substitution

A series of AB_x‐type triarylphosphine oxide monomers, bis‐(4‐fluorophenyl)‐(4‐hydroxyphenyl)phosphine oxide ( 4a ), bis‐(3,4‐difluorophenyl)‐(4‐hydroxyphenyl)phosphine oxide ( 4b ), and 4‐hydroxyphenyl‐bis‐(3,4,5‐trifluorophenyl)phosphine oxide ( 4c ) were prepared, characterized, and polymerized under nucleophilic aromatic substitution conditions [N‐methylpyrrolidone (NMP), K₂CO₃] to provide the corresponding hyperbranched poly(arylene ether phosphine oxide)s with number‐average molecular weights ranging from 9200 to 14,600 Da. NMR spectroscopic analysis indicated the presence of highly branched products with an approximate degree of branching of 0.57. The polymers were soluble in a variety of typical organic solvents and displayed excellent thermal stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1456–1467, 2002     

Effects of chemical structure and precursor on optical properties,thermo-mechanical properties,and molecular orientation and order of thin films of stiff aromatic polyimides

Thin films of rigid poly(p-phenylene pyromellitimide) (PMDA-PDA) and semi-rigid poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA), prepared by thermal imidization of the respective poly(amic acid) and poly(amic ethyl ester) precursors, were characterized with respect to their optical, thermomechanical and structural properties. Both polyimides exhibit an unusually large anisotropy between the in-plane and out-of-plane refractive indices, with n ranging from 0.198 to 0.216 for PMDA-PDA and from 0.230 to 0.242 for BPDA-PDA, nearly independent of the nature of the initial polyimide precursor, film thickness, and film preparation method. PMDA-PDA films exhibit low coefficients of thermal expansion (CTE's) of 6.5 and 8.2 ppm/C for the acid-derived and the ester-derived polyimides, respectively. In comparison, the BPDA-PDA films show CTE values of 4.3 and 18.0 for the acid-derived and ester-derived samples, respectively, despite the small differences in their optical anisotropies. Wide-angle x-ray diffraction patterns obtained in reflection and transmission for the various samples reveal a strong in-plane chain orientation for both PMDA-PDA and BPDA-PDA polyimides, with somewhat better intermolecular packing order for the ester-derived polyimide films. These effects of chemical structure and precursor on properties and structures of the polyimide films are discussed in light of recent theoretical considerations of semiflexible polymers.Dedicated to Prof E. W. Fischer on the occasion of his 65th birthday     

Synthesis and properties of polyimides derived from 1,7-bis(4-aminophenoxy)naphthalene and aromatic tetracarboxylic dianhydrides

The novel diamine, 1,7-bis(4-aminophenoxy)naphthalene (1,7-BAPON), was synthesized and used to prepared polyimides. 1,7-BAPON was synthesized through the nucleophilic displacement of 1,7-dihydroxynaphthalene with p-fluoronitrobenzene in the presence of K₂CO₃ followed by catalytic-reduction. Polyimides were prepared from 1,7-BAPON and various aromatic tetracarboxylic dianhydrides by the usual two-step procedure that included ring-opening polyaddition to give poly(amic acid)s, followed by cyclodehydration to polyimides. The poly(amic acid)s had inherent viscosities of 0.74-2.48 dL/g. Most of the polyimides formed tough, creasible films. These polyimides had glass transition temperatures between 247–278°C and their 10% weight loss temperatures were recorded in the range of 515–575°C in nitrogen atmosphere. © 1995 John Wiley & Sons, Inc.     

Synthesis and properties of new aromatic poly‐(ether benzoxazole)s from 2,2′‐bis(4‐amino‐3‐hydroxyphenoxy)biphenyl and aromatic dicarboxylic acid chlorides

A new bis(o‐aminophenol) with a crank and twisted noncoplanar structure and ether linkages, 2,2′‐bis(4‐amino‐3‐hydroxyphenoxy)biphenyl, was synthesized by the reaction of 2‐benzyloxy‐4‐fluoronitrobenzene with biphenyl‐2,2′‐diol, followed by reduction. Biphenyl‐2,2′‐diyl‐containing aromatic poly(ether benzoxazole)s with inherent viscosities of 0.52–1.01 dL/g were obtained by a conventional two‐step procedure involving the polycondensation of the bis(o‐aminophenol) monomer with various aromatic dicarboxylic acid chlorides, yielding precursor poly(ether o‐hydroxyamide)s, and subsequent thermal cyclodehydration. These new aromatic poly(ether benzoxazole)s were soluble in methanesulfonic acid, and some of them dissolved in m‐cresol. The aromatic poly(ether benzoxazole)s had glass‐transition temperatures of 190–251 °C and were stable up to 380 °C in nitrogen, with 10% weight losses being recorded above 520 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2656–2662, 2002     

Synthesis and properties of novel cardo aromatic poly(ether‐benzoxazole)s

Three new bis(ether‐acyl chloride) monomers, 1,1‐bis[4‐(4‐chloroformylphenoxy)phenyl]cyclohexane ( 1a ), 5,5‐bis[4‐(4‐chloroformylphenoxy)phenyl]‐4,7‐methanohexahydroindan ( 1b ), and 9,9‐bis[4‐(4‐chloroformylphenoxy)phenyl]fluorene ( 1c ), were synthesized from readily available compounds. Aromatic polybenzoxazoles bearing ether and cardo groups were obtained by the low‐temperature solution polycondensation of the bis(ether‐acyl chloride)s with three bis(aminophenol)s and the subsequent thermal cyclodehydration of the resultant poly(o‐hydroxy amide)s. The intermediate poly(o‐hydroxy amide)s exhibited inherent viscosities in the range of 0.35–0.71 dL/g. All of the poly(o‐hydroxy amide)s were amorphous and soluble in many organic polar solvents, and most of them could afford flexible and tough films by solvent casting. The poly(o‐hydroxy amide)s exhibited glass‐transition temperatures (T_g's) in the range of 141–169 °C and could be thermally converted into the corresponding polybenzoxazoles approximately in the region of 240–350 °C, as indicated by the DSC thermograms. Flexible and tough films of polybenzoxazoles could be obtained by thermal cyclodehydration of the poly(o‐hydroxy amide) films. All the polybenzoxazoles were amorphous and showed an enhanced T_g but a dramatically decreased solubility as compared with their poly(o‐hydroxy amide) precursors. They exhibited T_g's of 215–272 °C by DSC and showed insignificant weight loss before 500 °C in nitrogen or air. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4014–4021, 2001     

Synthesis and characterization of polyimides based on new fluorinated 3,3′-diaminobiphenyls

Two new fluorinated diamine monomers, 3,3′-diamino-5,5′-bis(trifluoromethyl)biphenyl and 3,3′-diamino-6,6′-bis(trifluoromethoxy)biphenyl, as well as a known nonfluorinated analog, 3,3′-diaminobiphenyl, were synthesized. Reaction of these diamines with rigid, highly rod-like dianhydrides produced poly(amic acid)s and polyimides, which were spin coated and thermally treated to produce polyimide films for evaluation in electronics applications. It was hoped that these polyimide films would exhibit an ideal combination of low thermal expansion, reduced water absorption, and low dielectric constant but with improved elongation due to the “crankshaft” nature of the 3,3′-biphenyl unit. Unlike polyimide films from analogous 4,4′-diaminobiphenyls, however, the 3,3′-diaminobiphenyl-based polyimides did not yield low in-plane thermal expansion coefficient in spin-coated films. In some cases high elongation was achieved, but with high thermal expansion. These new diamines may nevertheless find utility in polyimides and polyaramides for membrane, fiber, and other applications. Additionally, they may be useful in modifying the properties of polymer backbones via copolymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2441–2451, 1997     

Synthesis of polyimides with lower H2O-absorption and higher thermal properties by incorporation of intramolecular H-bonding

To introduce intramolecular hydrogen bonds in the polyimides (PIs), 5(6)-amino-2-(5-aminopyridin-2-yl)-benzimidazole (PyPABZ) were designed and synthesized. The intramolecular interaction was indicated by Fourier transform infrared when different copolyimides were prepared with 4,4′-oxydianiline and PyPABZ. These modified poly(benzimidazole imide)s eliminate the problem of high water absorption for benzimidazole (BI)-containing PIs in the materials applications. Moreover, the high packing coefficient and rigidity of these copolyimides caused by the strong intramolecular interaction from the H-bonding and the resulting PIs exhibited outstanding thermal properties such as high glass-transition temperature (T_g) and low coefficient of thermal expansion.     

Pattern formation of polyimide by using photosensitive polybenzoxazole as a top layer

A versatile method for positive-type patterning of polyimide (PI) based on a two-layer photosensitive poly(benzoxazole) (PSPBO) and poly(amic acid) (PAA) film has been developed to provide a promising material in the field of microelectronics. This patterning system consisted of a pristine PAA thick bottom-layer and a poly(o-hydroxy amide) (PHA) thin top layer with 9,9-bis[4-(tert-butoxycarbonyl-methyloxy)phenyl]fluorene (TBMPF) as a dissolution inhibitor, and (5-propylsulfonyloxyimino-5H-thiophene-2-ylidene)-(2-methylphenyl)-acetonitrile (PTMA) as a photoacid generator (PAG). The PHA and PAA were prepared from 4,4′-(hexafluoroisopropylidene)-bis(o-aminophenol) and 4,4′-oxybis(benzoic acid) derivatives, and 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 4,4′-oxydianiline, respectively, in N,N-dimethylacetamide. This two-layer system based on PHA (150-nm thickness) and PAA (1.5-μm thickness) showed high sensitivity of 35 mJ/cm² and high contrast of 10.3 when exposed to a 365 nm line (i-line), post-baked at 100 °C for 2 min, and developed in a 2.38 wt.% tetramethylammonium hydroxide aqueous solution/5 wt.% iso-propanol at 25 °C. A clear positive image of a 4-μm line-and-space pattern was printed on a film which was exposed to 100 mJ/cm² of i-line by a contact-printing mode and fully converted to the corresponding PBO/PI pattern upon heating at 350 °C, confirmed by FT-IR spectroscopy. This two-layer system could be applied to the patterning of various PAAs.     

Synthesis of polyphenylquinoxaline copolymers via aromatic nucleophilic substitution reactions of an A‐B quinoxaline monomer

A self‐polymerizable quinoxaline monomer (A‐B) has been synthesized and polymerized via aromatic nucleophilic substitution reactions. An isomeric mixture of self‐polymerizable quinoxaline monomers—2‐(4‐hydroxyphenyl)‐3‐phenyl‐6‐fluoroquinoxaline and 3‐(4‐hydroxyphenyl)‐2‐phenyl‐6‐fluoroquinoxaline—was polymerized in N‐methyl‐2‐pyrrolidinone (NMP) to afford high molecular weight polyphenylquinoxaline (PPQ) with intrinsic viscosities up to 1.91 dL/g and a glass‐transition temperature (T_g) of 251 °C. A series of comonomers was polymerized with A‐B to form PPQ/polysulfone (PS), PPQ/polyetherether ketone (PEEK), and PPQ/polyethersulfone (PES) copolymers. The copolymers readily obtained high intrinsic viscosities when fluorine was displaced in NMP under reflux. However, single‐electron transfer (SET) side reactions, which limit molecular weight, played a more dominant role when chlorine was displaced instead of fluorine. SET side reactions were minimized in the synthesis of PPQ/PS copolymers through mild polymerization conditions in NMP for longer polymerization times. Thus, the T_g's of PES (T_g = 220 °C), PEEK (T_g = 145 °C), and PS (T_g = 195 °C) were raised through the incorporation of quinoxaline units into the polymer. Copolymers with high intrinsic viscosities resulted in all cases, except in the case of PPQ/PEEK copolymers when 4,4′‐dichlorobenzophenone was the comonomer. © 2001 John Wiley & Sons, Inc. J Polym Sci A Part A: Polym Chem 39: 2037–2042, 2001     

Poly(arylether amides) and poly(aryletherketone amides) via aromatic nucleophilic substitution reactions of self‐polymerizable AB and AB2 monomers

Two new extended self‐polymerizable AB monomers, N‐(4‐fluorobenzoyl)‐4‐amino‐4′‐hydroxydiphenylether and N‐(4‐fluorobenzoyl)‐4‐amino‐4′‐hydroxybiphenyl, were prepared. The monomers were homopolymerized and copolymerized to high‐molecular‐weight, linear poly(arylether amides) in N‐methylpyrrolidone (NMP)/toluene in the presence of potassium carbonate at elevated temperature. The polymers retained NMP up to 200 °C. Samples containing small amounts of the solvent (5–10 wt %) were soluble in polar aprotic solvents. However, after complete removal of the NMP, the polymers were only soluble in strong acids such as sulfuric acid and methanesulfonic acid (MSA). The polymers, which had intrinsic viscosities of 0.57–1.49 dL/g (30.1 ± 0.1 °C in MSA), were semicrystalline with melting temperatures above 400 °C. Two new self‐polymerizable AB₂ amide monomers, N,N′‐bis(4‐fluorobenzoyl)‐3,4‐diamino‐4′‐hydroxydiphenylether and N,N′‐bis(4‐fluorobenzoyl)‐3,5‐diamino‐4′‐hydroxybenzophenone, were also prepared and polymerized to give a hyperbranched poly(arylether amide) and a hyperbranched poly(aryletherketone) amide. The arylfluoride‐terminated, amorphous polymers had intrinsic viscosities of 0.34 and 0.24 dL/g (30.0 ± 0.1 °C in m‐cresol), glass‐transition temperatures of 210–269 °C, and were soluble in a wide variety of organic solvents. Matrix‐assisted laser desorption/ionization time‐of‐flight analysis indicated that the components of the low‐molecular‐weight fractions contained cyclic structures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2374–2389, 2003     

New organosoluble and thermally stable poly(amide‐imide)s with benzoxazole or benzothiazole pendent groups: synthesis and characterization

Two new benzoxazole or benzothiazole‐containing diimide‐dicarboxylic acid monomers, such as 2‐[3,5‐bis(N‐trimellitimidoyl)phenyl]benzoxazole ( 2 _o ) or 2‐[3,5‐bis(N‐trimellitimidoyl)phenyl]benzothiazole ( 2 _s ) were synthesized from the condensation reaction between 3,5‐diaminobenzoic acid and 2‐aminophenol or 2‐aminothiophenol in polyphosphoric acid (PPA) with subsequent reaction of trimellitic anhydride in the presence of glacial acetic acid, respectively, and two new series of modified aromatic poly(amide‐imide)s were prepared. This preparation was done with pendent benzoxazole or benzothiazole units from the newly synthesized diimide‐dicarboxylic acid and various aromatic diamines by triphenyl phosphite‐activated polycondensation. In addition, the corresponding unsubstituted poly(amide‐imide)s were prepared under identical experimental conditions for comparative purposes. Characterization of polymers was accomplished by inherent viscosity measurements, FT‐IR, UV–visible, ¹H‐NMR spectroscopy and thermogravimetry. The polymers were obtained in quantitative yields with inherent viscosities between 0.39 and 0.81 dl g^?1. The solubilities of modified poly(amide‐imide)s in common organic solvents as well as their thermal stability were enhanced compared to those of the corresponding unmodified poly(amide‐imide)s. The glass transition temperature, 10% weight loss temperature, and char yields at 800°C were, respectively, 7–26°C, 17–46°C and 2–5% higher than those of the unmodified polymers. Copyright © 2010 John Wiley & Sons, Ltd.