Synthesis and characterization of BTDA-based polyamide-imides

A series of thermally-stable, tough, linear polyimides containing amide linkages were prepared. These materials have potential as high temperature films and coatings as well as matrix resins in graphite reinforced structures. The new polyamide-imides were prepared by reacting a group of isomers of diaminobenzanilide (DABA) with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) to form the polyamide-acid with subsequent thermal conversion to the polyamide-imide (PAI). Four polymers were synthesized from unsubstituted amide diamines and two others from N-substituted amide diamines. The properties of these polyamide-imides were compared to those of the polyimide of benzophenonetetracarboxylic dianhydride/3,3′-diaminobenzophenone (LARC–TPI) because their structures are similar, except for the presence of the more flexible amide linkages. These polymers exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films which showed good thermal stability and good resistance to organic solvents. Mechanical properties of the PAI films were better than those of LARC–TPI. Films of the 4,4′-isomer polyamide-imide exhibited an exceptionally high modulus and toughness during impact evaluation.     

Miscible polybenzimidazole blends with a benzophenone-based polyimide

Miscible blends of the aromatic polybenzimidazole, poly(2,2(m-phenylene)-5,5′-benzimidazole) (PBI), and the aromatic polyimide formed from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and 3,3′-diaminobenzophenone (LaRC TPI) have been prepared. Blends with PBI were prepared in N,N-dimethylacetamide solution starting with either the polyamic acid or a 95% imidized form of LaRC TPI; the blend was then precipitated into water or cast as films. The mixture was then imidized thermally to obtain PBI/LaRC TPI blends. Evidence for miscibility was obtained in the form of single composition dependent T_g's intermediate between those of the component polymers and single tan δ dynamic mechanical relaxation peaks. The IR spectra displayed shifts in the N? H stretching band, thereby providing evidence for specific interactions related to the miscibility of these two polymers.     

Palladium-doped polyimides: An X-ray photoelectron study

Five polyimide films prepared from 3,3′,4,4′-benzophenone tetracarboxylic acid'dianhydride (BTDA) and diamines, 4,4′-oxydianiline (ODA), 3,3′-diaminobenzophenone (DABP), or 3,3′-diaminodiphenylcarbinol (DADPC) and doped with Li₂PdCl₄ (LTP) or Pd[(CH₃)₂S]₂Cl₂ (PDS) were selected for a detailed x-ray photoelectron spectroscopic (XPS) study to determine the oxidation state of palladium and the relative distribution of this and other elements in these films, especially as they relate to electrical resistivity. XPS shows that Pd in the films is present as a mixture of zero and +2 valence states. Films that contain lithium as part of the dopant all show that metal is present as Li⁺ and Li₂O, a fact that may have a bearing on film electrical properties. An Auger electron spectroscopic (AES) or XPS profiling was performed on two of the electrically conductive films. A film doped with PDS reveals a majority of palladium at the surface as Pd(0) and much smaller amounts in film bulk as a mixture of Pd(0) and Pd(II). Film behavior is similar to a metal-vapor deposited film. An LTP doped film, by contrast, exhibits a homogeneous composition with a mixture of Pd(0) and Pd(II). These studies support others that use chemical etching on the film surfaces. Scanning electron microscopy (SEM) has been used to provide surface evaluations.     

Syntheses of Bissydnone Derivatives and Studies of Their Biological Activities

A new method to prepare 3,3′-ethylenebissydnone (40%), 3,3′-tetramethylenebissydnone (37%) and 3,3′-hexamethylenebissydnone (43%) from the corresponding alkylene diamine with paraformaldehyde and potassium cyanide were investigated. Some new bissydone: ?3,3′-trimethylenebissydnone (6%), 3,3′-(4,4′-diphenyl)bissydnonylmethane (9%) and 3,3′-(4,4′-diphenyi)bissydnonyl ether (28%) were synthesized from the corresponding diamine, paraformaldehyde, sodium bisulfite and potassium cyanide. Biological test of 3,3′-(4,4′-diphenyl)bissydnonylmethane shows significant response for coronary dilgtion test, inhibition of collagen induced platelet aggregation and moderate carditropic response. 3,3′-(4,4′-Diphenyl)bissydnonyl ether also shows inhibition of collagen induced platelet aggregation and moderate carditropic response.     

Thermotropic liquid crystalline polymer. III. Synthesis and properties of poly(amide-azomethine-ester)

A series of novel dialdehydes as new monomers, 4,4′-diformyl-α,ω-diphencarbonylalkane, 4,4′-diformyl-3,3′-methoxy-α,ω-diphencarbonylalkane, and 4,4′-diformyl-3,3′-ethoxy-α,ω-diphencarbonylalkane, was prepared from aliphatic diacid chloride with p-hydroxybenzaldehyde, vanillin, and 3-ethoxy-4-hydroxybenzaldehyde, respectively. A series of poly(amide-azomethine-ester)s was prepared by condensation of 4,4′-diaminoanilide with 4,4′-diformyl-α,ω-α,ω-diphencarbonylalkane, 4,4′-diformyl-3,3′-methoxy-α,ω-diphencarbonylalkane, and 4,4′-diformyl-3,3′-ethoxy-α,ω-diphencarbonylalkane, respectively. Their thermotropic liquid crystalline properties were examined by DSC microscope observations. In most cases, the mesophase extends up to ca. 288–380°C, where thermal decomposition prevents further observation.     

Cyclisation of benzils

Treatment of several substituted benzils [3,3′- and 4,4′-dimethyl-; 2,2′-, 3,3′- and 4,4′-dichloro-; 3,3′-dibromo-; 4-(N,N-dimethylamino)-] with an excess of chlorosulfonic acid gave the corresponding 3-chloro-2-phenylbenzofuran disulfonyl dichlorides. Disubstitution was confirmed by microanalytical and spectral data for the corresponding bis(N,N-dimethylaminsulfonamides). The positions of electrophilic substitution were not confirmed with 3,3′-dimethyl-, 2,2′- and 3,3′-dichlorobenzils. With 4,4′-dichlorobenzil, a smaller amount of chlorosulfonic acid enabled the isolation of 3,6,4′-trichloro-2-phenylbenzofuran-5-sulfonyl chloride, which was identified by X-ray analysis of the N,N-dimethylsulfonamide. The cyclisation failed with 3,3′-dimethoxy-, and 3,3′- and 4,4′-dinitrobenzils. The results have been interpreted mechanistically.     

Synthesis and properties of novel polyimides derived from 2,2′,3,3′‐benzophenonetetracarboxylic dianhydride

A new synthetic route to 2,2′,3,3′‐BTDA (where BTDA is benzophenonetetracarboxylic dianhydride), an isomer of 2,3′,3′,4′‐BTDA and 3,3′,4,4′‐BTDA, is described. Single‐crystal X‐ray diffraction analysis of 2,2′,3,3′‐BTDA has shown that this dianhydride has a bent and noncoplanar structure. The polymerizations of 2,2′,3,3′‐BTDA with 4,4′‐oxydianiline (ODA) and 4,4′‐bis(4‐aminophenoxy)benzene (TPEQ) have been investigated with a conventional two‐step process. A trend of cyclic oligomers forming in the reaction of 2,2′,3,3′‐BTDA and ODA has been found and characterized with IR, NMR, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and elemental analyses. Films based on 2,2′,3,3′‐BTDA/TPEQ can only be obtained from corresponding polyimide (PI) solutions prepared by chemical imidization because those from their polyamic acids by thermal imidization are brittle. PIs from 2,2′,3,3′‐BTDA have lower inherent viscosities and worse thermal and mechanical properties than the corresponding 2,3′,3′,4′‐BTDA‐ and 3,3′,4,4′‐BTDA‐based PIs. PIs from 2,2′,3,3′‐BTDA and 2,3′,3′,4′‐BTDA are amorphous, whereas those from 3,3′,4,4′‐BTDA have some crystallinity, according to wide‐angle X‐ray diffraction. Furthermore, PIs from 2,2′,3,3′‐BTDA have better solubility, higher glass‐transition temperatures, and higher melt viscosity than those from 2,3′,3′,4′‐BTDA and 3,3′,4,4′‐BTDA. Model compounds have been prepared to explain the order of the glass‐transition temperatures found in the isomeric PI series. The isomer effects on the PI properties are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2130–2144, 2004     

Thermally stable polymers from 1,4,5-naphthalene–tricarboxylic acid and aromatic tetramines

New thermally stable polymers that contained benzimidazole and benzimidazobenzoisoquinoline fragments in polymer chains were synthesized by one-stage cyclopolycondensation of aromatic tetramines (3,3′, 4,4′-tetraminodiphenyl ether, 3,3′,4,4′-tetraminodiphenyl methane, 3,3′,4,4′-tetraminodiphenyl sylfone, and 3,3′-diaminobenzidine) with 1,4,5-naphthalene tricarboxylic acid 4:5–anhydride in polyphosphoric acid and with 1,4,5-naphthalene tricarboxylic acid 4:5–anhydride 1-phenyl ester. All polymers obtained were soluble in concentrated sulfuric acid, 85% phosphoric acid, polyphosphoric acid, methane sylfonic acid. Some were soluble in formic acid. Thermogravimetric analyses indicated that these polymers were stable up to 450–500°C in air. The polymers had good hydrolytic stability.     

Dense Energetic Nitraminofurazanes

3,3′‐Diamino‐4,4′‐bifurazane ( 1 ), 3,3′‐diaminoazo‐4,4′‐furazane ( 2 ), and 3,3′‐diaminoazoxy‐4,4′‐furazane ( 3 ) were nitrated in 100 % HNO₃ to give corresponding 3,3′‐dinitramino‐4,4′‐bifurazane ( 4 ), 3,3′‐dinitramino‐4,4′‐azofurazane ( 5 ) and 3,3′‐dinitramino‐4,4′‐azoxyfurazane ( 6 ), respectively. The neutral compounds show very imposing explosive performance but possess lower thermal stability and higher sensitivity than hexogen (RDX). More than 40 nitrogen‐rich compounds and metal salts were prepared. Most compounds were characterized by low‐temperature X‐ray diffraction, all of them by infrared and Raman spectroscopy, multinuclear NMR spectroscopy, elemental analysis, and by differential scanning calorimetry (DSC). Calculated energetic performances using the EXPLO5 code based on calculated (CBS‐4M) heats of formation and X‐ray densities support the high energetic performances of the nitraminofurazanes as energetic materials. The sensitivities towards impact, friction, and electrostatic discharge were also explored. Additionally the general toxicity of the anions against vibrio fischeri, representative for an aquatic microorganism, was determined.     

Aromatic polyamides and polyimides derived from 3,3′-diaminobiphenyl: Synthesis,characterization, and molecular simulation study

In this article a new synthesis of 3,3′-diaminobiphenyl (3,3′-DABP) is described, along with the preparation and characterization of polyamides and polyimides based on it. Reactivity of this monomer was calculated by a molecular simulation study, using ab initio quantum-mechanical methods. Terephthaloyl and isophthaloyl chloride were used for the synthesis of polyamides, while 3,3′,4,4′-biphenylenetetracarboxylic acid dianhydride and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride were used for the synthesis of polyimides. Medium to high molecular weight polymers were attained, with inherent viscosities near or higher than 1.0 dL/g, the solubility of the 3,3′-DABP polymers was much better than that of the homologous polymers from benzidine (4,4′-DABP), the glass-transition temperatures were lower, by about 40°C, and the thermal resistance, as measured by thermogravimetry, was virtually the same. Amorphous films, made from cast polymer solutions, showed excellent mechanical properties, comparable to conventional aromatic polyamides and polyimides. Theoretical calculations demonstrated that the radius of giration, end-to-end distance and density of poly(3,3′-DABP-isophthalamide) were lower than those of poly(4,4′-DABP-isophthalamide), as a consequence of the chain folding induced in the backbone by the m-substitution in 3,3′-DABP. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4646–4655, 1999     

Polyimides from isomeric diphenylthioether dianhydrides

3,3′,4,4′‐Diphenylthioether dianhydride (4,4′‐TDPA), 2,3,3′,4′‐diphenylthioether dianhydride (3,4′‐TDPA), and 2,2′,3,3′‐diphenylthioether dianhydride (3,3′‐TDPA) were synthesized from 3‐chlorophthalic anhydride and 4‐chlorophthalic anhydride. A series of polyimides derived from the isomeric diphenylthioether dianhydrides with several diamines were prepared. The properties, such as the solubility, thermal and mechanical behavior, dynamic mechanical behavior, wide‐angle X‐ray diffraction, and permeability to some gases, were compared among the isomeric polyimides. Both 3,3′‐TDPA‐ and 3,4′‐TDPA‐based polyimides had good solubility in polar aprotic solvents and phenols. The 5% weight loss temperatures of all the obtained polyimides was near 500 °C in nitrogen. The glass‐transition temperatures decreased according to the order of the polyimides based on 3,3′‐TDPA, 3,4′‐TDPA, and 4,4′‐TDPA. The 3,4′‐TDPA‐based polyimides had the best permeability and lowest permselectivity, whereas the 4,4′‐TDPA‐based polyimides had the highest permselectivity and the lowest permeability of the three isomers. Furthermore, the rheological properties of thermoplastic polyimide resins based on the isomeric diphenylthioether dianhydrides were investigated, and they showed that polyimide 3,4′‐TDPA/4,4‐oxydianiline had the lowest melt viscosity among the isomers; this indicated that the melt processibility had been greatly improved. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 959–967, 2006     

Synthesis of 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans,the first representatives of dichloroamino- and chloroaminofurazans

First representatives of dichloroamino- and chloroaminofurazans, viz., 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans, were synthesized by the chlorination of 4,4′-diamino-3,3′-azofurazan with sodium hypochlorite in the CH₂Cl₂—H₂O mixture.     

Effects of structure on properties of some new aromatic-aliphatic polybenzimidazoles

Polybenzimidazoles were prepared in poly(phosphoric acid) from isophthalic, m- and p-phenylene diacetic, succinic, adipic, suberic, and sebacic acids and 3,3′-diaminobenzidine, 3,3′,4,4′-tetraaminodiphenyl ether and 3,3′,4,4′-tetraaminodiphenylmethane. The thermal, mechanical, and bonding properties were studied. A 3:1 copolymer of isophthalic and m-phenylenediacetic acid with 3,3′-diaminobenzidine showed the best results as far as isothermal oxidation resistance and thermal and processing characteristics.     

Comparative study on polyimides from isomeric 3,3′‐, 3,4′‐, and 4,4′‐linked bis(thioether anhydride)s

Three isomeric bis(thioether anhydride) monomers, 4,4′‐bis(2,3‐dicarboxyphenylthio) diphenyl ketone dianhydride (3,3′‐PTPKDA), 4,4′‐bis(3,4‐dicarboxyphenylthio) diphenyl ketone dianhydride (4,4′‐PTPKDA), and 4‐(2,3‐dicarboxyphenylthio)‐4′‐(3,4‐dicarboxyphenylthio) diphenyl ketone dianhydride (3,4′‐PTPKDA), were prepared through multistep reactions. Their structures were determined via Fourier transform infrared, NMR, and elemental analysis. Three series of polyimides (PIs) were prepared from the obtained isomeric dianhydrides and aromatic diamines in N‐methyl‐2‐pyrrolidone (NMP) via the conventional two‐step method. The PIs showed excellent solubility in common organic solvents such as chloroform, N,N‐dimethylacetamide, and NMP. Their glass‐transition temperatures decreased according to the order of PIs on the basis of 3,3′‐PTPKDA, 3,4′‐PTPKDA, and 4,4′‐PTPKDA. The 5% weight loss temperatures (T_5%) of all PIs in nitrogen were observed at 504–519 °C. The rheological properties of isomeric PI resins based on 3,3′‐PTPKDA/4,4′‐oxydianiline/phthalic anhydride showed lower complex viscosity and better melt stability compared with the corresponding isomers from 4,4′‐ and 3,4′‐PTPKDA. In addition, the PI films based on three isomeric dianhydrides and 2,2′‐bis(trifluoromethyl)benzidine had a low moisture absorption of 0.27–0.35%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of certain aromatic azopolyamides

Two new aromatic diamines, 2,2′-dimethyl-4,4′-diaminoazobenzene [benzenamine-(3,3′-dimethyl-4,4′-azobis)] and 2,2′-dichloro-4,4′-diaminoazobenzene [benzenamine-(3,3′-dichloro-4,4′-azobis)] were synthesized and their structures confirmed by IR, UV-visible, ¹H-NMR, ¹³C-NMR, and mass spectra. With these diamines, 16 aromatic polyamides were synthesized by both low-temperature solution and phosphorylation polycondensation methods. The polymers were characterized by viscosity, solubility, IR, UV visible, TGA, and DTA studies.     

Synthesis,characterization, and thermal stability of bismaleimides derived from maleimido benzoic acid

Bismaleimides containing ester, amide, urethane, and imide groups in the backbone were synthesized from maleimido benzoic acid via its acid chloride or isocyanate with 4,4′-dihydroxy-diphenyl-2,2-propane, 3,3′-diamino diphenyl sulfone, and 3,3′,4,4′-benzophenone tetracarboxylic acid anhydride by simple condensation or addition reaction. The new bismaleimides are characterized by IR, ¹H-NMR, and elemental analysis. DSC studies of these bismaleimides indicated a curing exotherm in the temperature range 150–270°C with heat of polymerization 30–50 J/g. Thermogravimetric analysis of the uncured resins showed high thermal stability and char yield for imide containing bismaleimide. The observed char yields of the bismaleimide resins are in accordance with the calculated C/H ratios.     

Self-condensation reaction of aromatic tetraamines in polyphosphoric acid

Ladder and partial ladder polymers have been obtained by self-condensation reactions of 1,2,4,5-tetraaminobenzene, 3,3′,4,4′-tetraaminodiphenyl ether, 3,3′-diaminobenzidine and 3,3′,4,4′-tetraaminodiphenyl sulfone in polyphosphoric acid. The products thus obtained are highly colored compounds with good thermal stability. They seem to be made up of polyquinoxaline or dihydrophenazine or a mixture of these two recurring units. They are slightly soluble in methanesulfonic acid and concentrated sulfuric acid and have inherent viscosities in the 0.2 to 0.4 range.     

Facile access to some new 3,3′-bipyrazole-ester derivatives utilizing bis-hydrazonoyl chlorides

The 1,3-dipolar cycloaddition reaction of bis-hydrazonoyl chlorides with ethyl propiolate and dimethyl acetylenedicarboxylate afforded diethyl 1,1′-aryl-3,3′-bipyrazole-4,4′-dicarboxylate and tetramethyl 1,1′-diaryl-3,3′-bipyrazole-4,4′,5,5′-tetracarboxylate esters, respectively. Heating the latter two compounds with a mixture of HCl/AcOH furnished the same product: 3,3′-bipyrazole-5,5′-dicarboxylic acid. Reaction of the tetracarboxylate ester with aniline derivatives and with hydrazine gave the corresponding bipyrazole-fused heterocycles. Heating the dicarboxylic acid with 2-aminothiazole gave the corresponding bis-amide derivative. The structures of the products were established by elemental analysis, spectral data, and single-crystal X-ray crystallography.     

Synthesis and characterization of photosensitive polyimides from methylthiomethyl-substituted 4,4′-diaminodiphenylmethanes and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride

A series of novel polyimides are synthesized by the reaction of 3,3′,4,4′-benzophenonete-tracarboxylic dianhydride (BTDA) with four methylthiomethyl-substituted aromatic diamines: 3-methylthiomethyl-4,4′-diaminodiphenylmethane ( I ), 3,3′-dimethylthiomethyl-4,4′-diaminodiphenylmethane ( II ), 3,3′,5-trimethylthiomethyl-4,4′-diaminodiphenylmethane ( III ), and 3,3′,5,5′-tetramethylthiomethyl-4,4′-diaminodiphenylmethane ( IV ) in refluxing m-cresol. The polyimide of diamine I and BTDA carrying only one pendant methylthiomethyl group in a repeating unit is readily soluble in m-cresol, chloroform, and polar aprotic solvents. Increasing the number of the pendant group results in higher solubility. These fully imidized polyimides are also intrinsically photosensitive. The fraction of photoreactive benzophenone sites that relates to the rate and degree of completion of photocrosslinking reaction increases systematically with the increase of the pendant group content. As the average number of the pendant group in a repeating unit reaches 3, 63% of benzophenone sites are found to be photoreactive. These methylthiomethyl-substituted polyimides possess moderate tensile strength which falls in the range of 67–81 MPa. As a result of the increase of methylthiomethyl content, this type of polyimide reveals higher glass transition temperature but lower thermal stability due to the considerable dimension of the pendant group and the ready cleavage nature of the C? S bond. © 1993 John Wiley & Sons, Inc.     

Influence of the bisphenol structure on the direct synthesis of sulfonated poly(arylene ether) copolymers. I

New sulfonated poly(arylene ether sulfone) copolymers with high molecular weights were successfully synthesized with controlled degrees of disulfonation of up to 70 mol % via the direct copolymerization of sulfonated aromatic dihalides, aromatic dihalides, and one of four structurally distinct bisphenols. The disodium salts of the 3,3′‐disulfonated‐4,4′‐dichlorodiphenyl sulfone and 3,3′‐disulfonated‐4,4′‐difluorodiphenyl sulfone comonomers were synthesized via the sulfonation of 4,4′‐dichlorodiphenyl sulfone or 4,4′‐difluorodiphenyl sulfone with 30% fuming sulfuric acid at 110 °C. Four bisphenols (4,4′‐bisphenol A, 4,4′‐bisphenol AF, 4,4′‐biphenol, and hydroquinone) were investigated for the syntheses of novel copolymers with controlled degrees of sulfonation. The composition and incorporation of the sulfonated repeat unit into the copolymers were confirmed by ¹H NMR and Fourier transform infrared spectroscopy. Solubility tests on the sulfonated copolymers confirmed that no crosslinking and probably no branching occurred during the copolymerizations. Tough, ductile films were solvent‐cast that exhibited increased water absorption with increasing degrees of sulfonation. These copolymers are promising candidates for high temperature proton‐exchange membranes in fuel cells, which will be reported separately in part II of this series. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2264–2276, 2003