One-pot synthesis of polyimides via Ni-catalyzed coupling of bis(chlorophthalimide)s

A one-pot synthesis method for the preparation of polyimides containing biphenyl units was developed via nickel-catalyzed coupling reaction of bis(chlorophthalimide)s which were prepared from chlorophthalic anhydrides and diamines in xylene. The resulting polyimides had inherent viscosities of above 0.60 dL g⁻¹. In the meantime, the copolymerizations from a mixture of three isomeric bis(chlorophthalimide)s gave the polymers with inherent viscosities of 0.36-0.55 g dL⁻¹. The solubility and film formability of the copolymers were better than those of homopolymers from bis(4-chlorophthalimide). The 10% weight loss of these polyimides was between 470 and 531 °C.     

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     

Sulfide and sulfoxide based poly(ether-amide)s: Synthesis and characterization

Two new diacid monomers, 2,2′-sulfide bis(4-methyl phenoxy acetic acid) and 2,2′-sulfoxide bis(4-methyl phenoxy acetic acid) were successfully synthesized by refluxing the 2,2′-sulfide bis(4-methyl phenol) and 2,2′-sulfoxide bis(4-methyl phenol) with chloroacetonitrile in the presence of potassium carbonate, and subsequent basic reduction. Two novel series of poly(sulfide-ether-amide)s and poly(sulfoxide-ether-amide)s with aliphatic units in the main chain were prepared from diacids with various diamines.The polyamides were obtained in quantitative yields and their inherent viscosities were in the range of 0.43-0.89 dl g⁻¹ at a concentration of 0.5 g dl⁻¹ in N,N-dimethylacetamide (DMAc) solvent at 25 °C. They showed good thermal stability. The temperature for 10% weight loss in argon atmosphere was in the range of 350-415 °C. The polymers showed glass transition temperatures between 228 and 261 °C. Almost all of the polyamides were readily soluble in a variety of polar solvents such as N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO).     

Thermal decomposition products of copoly(arylene ether sulfone)s characterized by direct pyrolysis mass spectrometry

Pyrolysis products with mass of up to 850 Da were detected by direct pyrolysis mass spectrometric (DPMS) analysis of a series of copoly(arylene ether sulfone)s (PES-PPO) synthesized by nucleophilic condensation of either 4,4′-dichlorodiphenylsulfone (CDPS) or 4,4′-bis-(4-chlorophenyl sulfonyl) biphenyl (long chain dichloride, LCDC) with different molar ratios of hydroquinone (HQ) or dihydroxydiphenylsulfone (HDPS). Pyrolysis products retaining the repeating units of the initial copolymers were formed at temperatures ranging from 420 °C to 470 °C (near the initial decomposition temperature). At temperatures higher than 450 °C were observed products containing biphenyl units, formed by the elimination process of SO₂ from diphenyl sulfone bridges. Products having biphenyl and dibenzofuran moieties were detected in the mass spectra recorded at temperatures above 550 °C. These units were formed by loss of hydrogen atom from diphenyl ether bridges. Although the EI (18 eV) mass spectra of the pyrolysis products of the samples investigated were very similar, it was found that the relative intensity of some ions reflects the molar composition of the copolymers analysed. Cyclic and linear oligomers with very low molecular mass, present in the crude copolymers, were also detected by DPMS. Thermogravimetric analysis also showed their excellent thermal stability below 400 °C. It indicates that the copolymers yield a char residue of 40-45% at 800 °C, which increases with the PPO mole fraction in the samples.     

Regularly alternating poly(amideimide)s containing pendent pentadecyl chains: Synthesis and characterization

Two new aromatic diamines containing preformed amide linkages, viz., N,N′-(4-pentadecyl-1,3-phenylene)bis(4-aminobenzamide) I and N,N′-(4-pentadecyl-1,3-phenylene)bis(3-aminobenzamide) II, were synthesized by reaction of 4-pentadecylbenzene-1,3-diamine with 4-nitrobenzoylchloride and 3-nitrobenzoylchloride, followed by reduction of the respective dinitro derivatives. A series of new poly(amideimide)s was synthesized by polycondensation of I and II with four commercially available aromatic dianhydrides, viz., pyromellitic dianhydride (PMDA), 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 4,4′-oxydiphthalic anhydride (ODPA), and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) in N,N-dimethylacetamide (DMAc) employing conventional two step method via poly(amic acid) intermediate followed by thermal imidization. Reference poly(amideimide)s were synthesized by polycondensation of N,N′-(1,3-phenylene)bis(4-aminobenzamide) and N,N′-(1,3-phenylene)bis(3-aminobenzamide) with the same aromatic dianhydrides. Inherent viscosities of poly(amideimide)s containing pendent pentadecyl chains were in the range 0.37-1.23 dL/g in N,N-dimethylacetamide at 30 ± 0.1 °C indicating the formation of medium to high molecular weight polymers. The poly(amideimide)s containing pendent pentadecyl chains were found to be soluble in N,N-dimethylacetamide, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and pyridine and could be cast into transparent, flexible and tough films from their N,N-dimethylacetamide solution. Wide angle X-ray diffraction patterns exhibited broad halo indicating that the polymers were essentially amorphous in nature. X-ray diffractograms also displayed sharp reflection in the small angle region (2θ ≈ 3°) for poly(amideimide)s containing pentadecyl chains indicating the formation of layered structure arising from packing of flexible pentadecyl chains. The glass transition temperatures observed for reference poly(amideimide)s were in the range 331-275 °C and those for poly(amideimide)s containing pendent pentadecyl chains were in the range 185-286 °C indicating a large drop in T_g owing to the “internal plasticization” effect of pentadecyl chains. The temperature at 10% weight loss (T₁₀), determined by TGA in nitrogen atmosphere, were in the range 460-480 °C indicating their good thermal stability.     

Novel organosoluble and colorless poly(ether imide)s based on 1,1-bis[4-(3,4-dicarboxyphenoxy)phenyl]cyclohexane dianhydride and trifluoromethyl-substituted aromatic bis(ether amine)s

A series of novel fluorinated poly(ether imide)s (IV) having inherent viscosities of 0.70-1.08 dL/g were prepared from 1,1-bis[4-(3,4-dicarboxyphenoxy)phenyl]cyclohexane dianhydride (I) and various trifluoromethyl (CF₃)-substituted aromatic bis(ether amine)s II_a-g by a standard two-step process with thermal and chemical imidization of poly(amic acid) precursors. These poly(ether imide)s showed excellent solubility in many organic solvents and could be solution-cast into transparent, flexible, and tough films. These films were essentially colorless, with an ultraviolet-visible absorption edge of 375-380 nm and a very low b^∗ value (a yellowness index) of 5.5-7.3. They also showed good thermal stability with glass-transition temperatures of 207-269 °C, 10% weight loss temperatures in excess of 474 °C, and char yields at 800 °C in nitrogen more than 62%. In comparison with analogous V series poly(ether imide)s without the -CF₃ substituents, the IV series polymers showed better solubility, lower color intensity, and lower dielectric constants.     

Synthesis and characterization of poly(amideimide)s containing pendent flexible alkoxy chains

A series of aromatic diacylhydrazides containing pendent flexible alkoxy chains, viz., 5-butyloxyisophthalicacid dihydrazide, 5-octyloxyisophthalicacid dihydrazide, 5-dodecyloxyisophthalicacid dihydrazide and 5-hexadecyloxyisophthalicacid dihydrazide were synthesized by the hydrazinolysis reaction of the corresponding aromatic esters with hydrazine hydrate. Diacylhydrazides were each polycondensed with aromatic dianhydrides, viz., 4,4′-oxydiphthalic anhydride (ODPA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) to obtain new poly(amideimide)s. Poly(amideimide)s had inherent viscosity in the range 0.55-0.88 dL/g in N,N-dimethylacetamide (DMAc) at 30 ± 0.1 °C. Poly(amideimide)s were found to be soluble in DMAc, N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone (NMP) and pyridine and could be cast into tough, flexible and transparent films from a solution in DMAc. X-ray diffractograms revealed that poly(amideimide)s with longer alkoxy chains had layered structures. Glass transition temperature of poly(amideimide)s containing pendent flexible alkoxy chains were in the range 215-245 °C. Temperature at 10% weight loss was in the range 380-410 °C in nitrogen atmosphere indicating good thermal stability of poly(amideimide)s.     

Synthesis of amorphous copoly(thioether sulfone)s with high refractive indices and high Abbe numbers

New thermoplastic random copoly(thioether sulfone)s with high refractive indices and high Abbe numbers have been developed by the simultaneous introduction of sulfide, sulfone, and alicyclic units in the polymer chains. They were prepared by random copolymerization of 2,5-bis(sulfanylmethyl)-1,4-dithiane (BMMD) and cyclohexane-1,4-dithiol (CHDT) with divinyl sulfone (DVS) based on the Michael polyaddition. Tough, flexible, colorless and transparent copoly(thioether sulfone) (poly(BMMD/CHDT-DVS)) films were obtained, and they showed good thermal stability with the 5% weight-loss at temperatures over 300 °C in nitrogen, and the glass transition temperatures of 42-50 °C. The inherent amorphous nature of films was confirmed by differential scanning calorimetry. Poly(BMMD/CHDT-DVS) exhibited quite high level of refractive indices and Abbe numbers as thermoplastics, in the range of 1.6512-1.6022 and 42.6-50.6, respectively. The experimental refractive indices and their wavelength dispersions were well reproduced by the DFT calculations with the aid of empirical density prediction.     

Synthesis of novel crosslinked sulfonated poly(ether sulfone)s using bisazide and their properties for fuel cell application

Novel crosslinked sulfonated poly(ether sulfone)s (PESs) were prepared by thermal irradiation of the allyl-terminated telechelic sulfone polymers using a bisazide. The sulfonated polymers in different comonomer compositions were fully characterized by ¹H NMR, and the crosslinked structure was also verified by FT-IR spectroscopic analyses. Having both the uniform distribution of the hydrophilic conductive sites and controlled hydrophobic nature by minimized crosslinking over the rigid rod poly(ether sulfone) backbone, the crosslinked polymer membrane (PES-60) offered excellent proton conductivity of 0.79 S cm⁻¹ at 100 °C together with hydrolytic and oxidative stability. In addition, only 17% of methanol permeability of the Nafion^® was observed for the crosslinked PES-60.     

Effects of the structure on the properties of new poly(arylene ether sulfone)s containing naphthalene units

A series of new poly(arylene ether sulfone)s has been obtained by solution condensation polymerisation starting from 1,5- and 2,6-bis-(4-fluorosulfonyl)naphthalene with various aromatic dihydroxy compounds. The polymers, obtained in quantitative yields, possessed inherent viscosities in the range 0.28-0.68 dl g⁻¹, had good thermal stability (10% weight loss temperatures were above 405 and 420 °C respectively in nitrogen and air) and high glass transition temperatures (in the range 217-258 °C). They have been characterised by elemental and infrared analyses, GPC and wide-angle X-ray diffraction. The properties of these poly(arylene ether sulfone)s have been compared with those of the corresponding poly(arylene ether ketone)s.     

Synthesis,characterization, and thermal properties of novel arylene sulfone ether polyimides and polyamides

A new aromatic sulfone ether diamine was synthesized by nucleophilic aromatic substitution reaction of 5‐amino‐1‐naphthol with bis(4‐chlorophenyl) sulfone in the presence of potassium carbonate in a polar aprotic solvent. Polycondensation reactions of the obtained diamine with pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), and hexafluoroisopropylidene diphthalic anhydride (6FDA) resulted in preparation of thermally stable poly(sulfone ether imide)s. Poly(sulfone ether amide)s also were prepared by reaction of the diamine with terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC). The prepared monomer and polymers were characterized by conventional methods. Physical and mechanical properties of polymers, including thermal stability, thermal behavior, solution viscosity, solubility behavior, and modulus, also were studied. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1487–1492, 2000     

Adhesive and dielectric properties of novel polyimides with bis(3,3′-aminophenyl)-2,3,5,6-tetrafluoro-4-trifluoromethyl phenyl phosphine oxide (mDA7FPPO)

Polyimides with a low dielectric constant and excellent adhesion were prepared from a diamine containing phosphine oxide and fluorine groups, bis(3,3′-aminophenyl-2,3,5,6-tetrafluoro-4-trifluoromethyl phenyl phosphine oxide (mDA7FPPO), and rigid-rod type dianhydride containing fluorine groups, such as 3,6-di(3′,5′-bis(trifluoromethyl)-phenyl)pyromellitic dianhydride (12FPMDA). The polyimides were synthesized via the known two-step process, preparation of poly(amic-acid) followed by solution imidization, and characterized by FT-IR, NMR, DSC, TGA and TMA. In addition, their solubility, intrinsic viscosity, dielectric constant and adhesive property were also evaluated. For comparison, 3,6-di(4′-trifluoromethylphenyl) pyromellitic dianhydride (6FPMDA) and 3,6-diphenylpyromellitic dianhydride (DPPMDA) were also utilized. The prepared polyimides exhibited high T_g (276-314 °C), excellent thermal stability (>500 °C in air), good adhesive property (104.7-126.3 g/mm), good solubility, and very low dielectric constant (2.34-2.89).     

Synthesis and properties of novel fluorinated polynaphthalimides derived from 1,4,5,8-naphthalenetetracarboxylic dianhydride and trifluoromethyl-substituted aromatic bis(ether amine)s

A series of novel fluorinated polynaphthalimides (PNIs) (2a-g) were synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and trifluoromethyl (CF₃)-substituted aromatic bis(ether amine)s (1a-g) by high-temperature solution polycondensation in m-cresol using isoquinoline as catalyst. Almost all the PNIs were readily soluble in polar solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) and could be solution-cast to transparent and tough films with high tensile strengths. The PNIs exhibited high thermal stability, with glass-transition temperatures of 262-383 °C, 10% weight loss temperatures above 528 °C in nitrogen or air, and char yields at 800 °C in nitrogen higher than 50%. In comparison with analogous PNIs without the -CF₃ substituents, these fluorinated PNIs revealed an enhanced solubility and better film-forming capability.     

Synthesis and properties of novel organosoluble polyimides derived from bis[3-(4-amino-2-trifluoromethylphenoxy) phenyl] ether

A new aromatic ether diamine, bis[3-(4-amino-2-trifluoromethylphenoxy) phenyl] ether, was successfully synthesized via nucleophilic substitution reaction of 3,3′-oxydiphenol and 2-chloro-5-nitrotrifluoromethylbenzene, followed by a catalytic reduction. A series of new polyimides were synthesized from the diamine with various commercially available aromatic dianhydrides via a conventional two-stage process, i.e. ring-opening polyaddition forming the poly(amic acid)s and further thermal or chemical imidization forming polyimides. The resulting polyimides exhibited good solubility in polar solvents, such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidinone and common solvents such as chloroform, tetrahydrofuran upon heating and possessed the inherent viscosities of 0.51-0.68 dL/g. The resulting strong and flexible films exhibited excellent thermal stability with the temperature at 10% weight loss is above 502 °C and the glass transition temperature in the range of 191-232 °C. The polyimides also were found to possess high optical transparency.     

Preparation and thermal properties of diglycidylether sulfone epoxy

A diglycidylether sulfone monomer (sulfone type epoxy monomer, SEP) was prepared from bis(4-hydroxyphenyl) sulfone (SDOL) and epichlorohydrin without any NaOH or KOH as basic catalyst. FT-IR, ¹H NMR, ¹³C NMR and mass spectroscopic instruments were utilized to determine the structure of the SEP monomer. The cured SEP epoxy material exhibited not only a higher T_g (163.81 °C) but also a higher T_g than pristine DGEBA (from 111.25 °C to 139.17 °C) when the SEP monomer moiety had been introduced into the DGEBA system. The thermal stability of cured epoxy herein was investigated by thermogravimetric analysis (TGA). The results demonstrated that the sulfone group of the cured SEP material decomposed at lower temperatures and formed thermally stable sulfate compounds, improving char yield and enhancing resistance against thermal oxidation. Additionally, the IPDT and char yield of the cured SEP epoxy (IPDT = 1455.75, char yield = 39.67%) exceeded those of conventional DGEBA epoxy (IPDT = 667.27, char yield = 16.25%).     

Poly(1,3,4-oxadiazole-ether-imide)s and their polydimethylsiloxane-containing copolymers

Poly(1,3,4-oxadiazole-ether-imide)s were prepared by thermal imidization of poly(amic-acid) intermediates resulting from the solution polycondensation reaction of a bis(ether-anhydride), namely 2,2′-bis-[(3,4-dicarboxyphenoxy)phenyl]-1,4-phenylenediisopropylidene dianhydride, with different aromatic diamines containing 1,3,4-oxadiazole ring, such as 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole, 2,5-bis[p-(4-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2-(4-dimethylaminophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole. Poly(1,3,4-oxadiazole-ether-imide)-polydimethylsiloxane copolymers were prepared by polycondensation reaction of the same bis(ether-anhydride) with equimolar quantities of an aromatic diamine having 1,3,4-oxadiazole ring and a bis(aminopropyl)polydimethylsiloxane oligomer of controlled molecular weight. A solution imidization procedure was used to convert quantitatively the poly(amic-acid) intermediates to the corresponding polyimides. All the polymers were easily soluble in polar organic solvents such as N-methylpyrrolidone and N,N-dimethylacetamide. The polymers showed good thermal stability with decomposition temperature being above 400 °C. Solutions of some polymers in N-methylpyrrolidone exhibited blue fluorescence, having maximum emission wavelength in the range of 370-412 nm.     

Electrochromic properties of novel strictly alternating poly(amine-amide-imide)s with electroactive triphenylamine moieties

A series of novel triphenylamine-containing aromatic poly(amine-amide-imide)s (PAAIs) were prepared by the phosphorylation polyamidation reactions from the diamine, N,N′-bis(4-aminophenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various imide ring-preformed dicarboxylic acids. All the PAAIs were amorphous, had good solubility in many polar aprotic solvents, and exhibited excellent thin film forming capability with good mechanical properties. They displayed relatively high glass-transition temperatures (220-306 °C) and good thermal stability, with 10% weight-loss temperatures in excess of 522 °C in air or nitrogen and char yields at 800 °C in nitrogen higher than 66%. The solutions of polymers in NMP exhibited strong UV-vis absorption bands with a maximum around 315 nm. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the PAAIs prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidation redox couples at 0.63 and 1.01 V vs. Ag/AgCl in acetonitrile solution. All the PAAIs revealed very stable electrochromic characteristics, changing color from original pale brownish to green, and then to blue at 0.67 and 1.08 V, respectively.     

Synthesis and characterization of electrochromic poly(amide-imide)s based on the diimide-diacid from 4,4′-diamino-4″-methoxytriphenylamine and trimellitic anhydride

A dicarboxylic acid bearing two preformed imide rings, namely 4,4′-bis(trimellitimido)-4″-methoxytriphenylamine (3), was prepared by the condensation of 4,4′-diamino-4″-methoxytriphenylamine (2) and two molar equivalents of trimellitic anhydride (TMA). A new family of aromatic poly(amide-imide)s (PAIs) containing the electroactive triphenylamine (TPA) unit were prepared by the triphenyl phosphite activated polycondensation of the diimide-diacid 3 with various aromatic diamines. All the polymers were readily soluble in many organic solvents and could be solution-cast into tough and flexible polymer films. They displayed high glass-transition temperatures (269-313 °C) and good thermal stability, with 10% weight-loss temperatures in excess of 521 °C in nitrogen and char yields at 800 °C in nitrogen higher than 68%. Cyclic voltammograms of the PAI films cast onto an indium-tin oxide (ITO)-coated glass substrate exhibited one reversible oxidation redox couple at 0.91-0.93 V vs. Ag/AgCl in acetonitrile solution. The polymer films revealed a good electrochemical and electrochromic stability, with a color change from colorless neutral form to blue oxidized form at applied potentials ranging from 0.0 to 1.2 V. The PAIs containing the TPA unit in both imide and amide segments showed multicolor electrochromism: pale yellow in the neutral state, green in the semi-oxidized state, and deep blue in the fully oxidized state.     

Synthesis and characterization of polyimides based on novel isomeric perfluorinated naphthylenediamines

Novel highly fluorinated polyimides containing hexafluoronaphthylene fragment in the main chain were prepared by the two-stage polymerization of 2,7- and 2,6-diaminohexafluoronaphthalenes with 4,4′-oxydiphthalic anhydride: polycondensation in a solution at 80 °C followed by high-temperature solid-state chain extension. The influence of hexafluoronaphthylene fragment isomerism on the key polyimide features - molecular weight, thermal stability, solubility, optical properties - was characterized. Polyimides based on 2,7-diaminohexafluoronaphthalene or easily accessible mixture of isomeric diamines formed the flexible, transparent, and thermostable films.     

Preparation and characterization of colorless alternate poly(amide-imide)s based on trimellitic anhydride and 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone

Alternate poly(amide-imide) [P(A-alt-I)] was synthesized from two aromatic diamines and trimellitic anhydride (TMA). When the diamine was 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone (BAPS), the resulted P(A-alt-I) was found to be of light color. Specifically, when BAPS was located between two amide groups in the P(A-alt-I) chain, the P(A-alt-I) was almost colorless. A series of P(A-alt-I)s (Series III) containing BAPS was synthesized through direct polycondensation of an aromatic dicarboxylic acid prepared from various aromatic diamines and TMA, as well as BAPS. Polymers of Series III were much lighter in color than those of the isomeric series (BAPS was located between two imide group). The series of P(A-alt-I)s III had inherent viscosities ranging 0.69–1.35 dL/g and good solubility in various solvents. The tensile strengths, elongations to break, and initial moduli of the films were 72–107 MPa, 7–12% and 1.93–2.39 GPa, respectively, and most of the films had no yielding. Polymers of Series III had glass transition temperatures 210–272°C and 10% weight loss temperatures in nitrogen 518–545°C, indicating excellent thermal stability. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2421–2428, 1999