Compared properties of related aromatic poly(1,3,4-oxadiazole-amide)s

Two series of aromatic poly(1,3,4-oxadiazole-amide)s have been synthesized by low-temperature solution polycondensation reaction of equimolar amounts of aromatic diamines containing preformed oxadiazole rings with diacid chlorides having silicon or hexafluoroisopropylidene groups. These polymers are soluble in polar aprotic solvents and show high thermal stability with decomposition temperature being above 400 °C and glass transition temperature in the range of 250-350 °C. The polyoxadiazole-amides have weight- and number-average molecular weights in the range of 207 000-330 000 and 77 000-131 000, respectively. Conformational parameters of these polymers were calculated by Monte Carlo method with allowance for hindered rotation and discussed in relation with thermal properties. Polymer solutions in NMP were processed into thin free-standing films that showed good mechanical properties with tensile strength in the range of 50-100 MPa, tensile modulus in the range of 2.25-3.56 GPa and elongation to break in the range of 1.65-8.58%.     

Synthesis and evaluation of properties of novel poly(benzimidazole‐amide)s

Novel aromatic polyamides have been prepared by a combination of diacids containing preformed benzimidazole rings and aromatic diamines. By the phosphorylation method of polycondensation, polymers of high molecular weight (inherent viscosities between 0.81 and 2.13 dL/g) were obtained, which showed good solubility in polar aprotic solvents. The combination of aromatic amide linkages and benzimidazole rings along the polymer chain endowed the polymers with high thermal resistance and excellent mechanical properties. Glass transition temperatures fell in the range of 290–330 °C as measured by differential scanning calorimetry, and initial decomposition temperatures under nitrogen were over 480 °C as measured by thermogravimetric analysis. Some polymer films showed outstanding tensile strength (over 150 MPa) and moduli (up to 5 GPa). The presence of benzimidazole rings in the current polyamides greatly enhanced their hydrophilicity in comparison with classical wholly aromatic polyamides; thus, although aromatic polyamide films normally show water sorption values of only 4–8%, some of the current poly(benzimidazole amide)s show water sorption up to 19% in a 65% relative humidity atmosphere. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7566–7577, 2008     

Thermally stable polymers containing 1,3,4-oxadiazole units obtained from Huisgen reaction

Thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic/aliphatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chlorides in pyridine as solvent.The obtained polymers are insoluble or slightly soluble even in polar aprotic solvents such as DMSO and DMF.Relatively high inherent viscosity values（0.61-1.33 dL/g,in 0.125%H₂SO₄ at 25℃） were observed for these compounds.Thermal analyses of the polymers using DSC and TGA techniques showed that the polymers have improved thermal stabilities.The glass transition temperature has not been observed in the fully aromatic polymers,but the polymers obtained from 5-[6-（1H-tetrazol -5-yl）hexyl]-lH-tetrazole（Ⅳ） showed very clear T_g.A model reaction was also investigated and the resulting bis-1,3,4-oxadiazole compound was characterized by conventional spectroscopy methods.     

Studies on heat resistant poly(aryl pyromellitimide-ether)s

A new series of aromatic heterocyclic poly(aryl pyromellitimide-ether)s have been synthesized from various disodium metal bisphenolate salts with an N,N′-bis(p-nitrophenyl)pyromellitimide via aromatic nitro displacement solution polycondensation in dipolar aprotic solvent at elevated temperature. The reaction was rapid and free of side reactions, with good yield. The resultant polymers were characterized by intrinsic viscosity, infrared and ¹H-, ¹³C-NMR spectroscopy. Thermal behavior of the synthesized polymers was evaluated by thermogravimetric analysis and correlated with their structures. The poly(tetraphenyl methane pyromellitimide-ether) showed better thermal stability than the other polymers. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterisation of poly(ester-amide)s from aromatic bisoxazoline precursors

A series of novel aliphatic aromatic poly(ester-amide)s (PEA) have been synthesized by condensation reaction of aromatic bisoxazolines with aliphatic dicarboxylic compounds. These polymers have a number average molecular weight of 20,000-25,000. Depending of the aromatic structure of the bisoxazoline precursor, they are either amorphous or semi-crystalline. A good solubility in aprotic solvents was observed for all PEAs.     

Comparative study of the thermal properties of related aromatic polyhydrazides and poly(1,3,4-oxadiazole)s

Studies were undertaken to ascertain the thermal behavior of several new types of aromatic polyhydrazides and poly(1,3,4-oxadiazole)s containing different functional groups. Results of thermal analysis investigations indicate that all the polyoxadiazoles are remarkably heat-resistant when heated in nitrogen at elevated temperature but somewhat less heat-resistant than fully aromatic polyoxadiazoles. Most of the new polyoxadiazoles decompose when heated to about 450°C. The incorporation of tetraphenyl silane, hexafluoroisopropylidene, phthalido or phenoxytherephthalic groups into the main chain decrease the glass transition temperature of aromatic poly(1,3,4-oxadiazole)s. In the case of the silicon-containing polymers the glass transition temperature is independent of the other groups incorporated in the same macromolecule. The cyclization process of all investigated polyhydrazides takes place in the range between 320 and 390°C.     

Characterization of novel modified amorphous poly (ether sulphone)s

New high-temperature amorphous polymers with chlorine, amine, and maleimide chain-ends have been synthesized by nucleophilic polycondensation and fully characterized by ¹³C-NMR, ¹H-NMR, and potentiometric titration. From chain-end determination, number average molecular masses were calculated. It was confirmed that transetherification during the synthesis led to a randomized polymer of the monomer residues. For nominally amine-ended polymers obtained by addition of m-aminophenol at the end of the synthesis, a small amount of hydroxyl chain-ends was observed. This is ascribed also to transetherification. Complete reaction of the amine chain-ends with maleic anhydride was demonstrated. Reaction of hydroxyl chain-ends with acetic anhydride was also observed. The thermal stability of these different polymers was investigated; lower thermal stability was observed for amine and maleimide-ended polymers. By two different methods, a T_g around 270d°C was determined for these novel amorphous aromatic polymers. © 1994 John Wiley & Sons, Inc.     

Synthesis and characterization of deuterated poly(arylene ether sulfones)

Selectively deuterated poly(arylene ether sulfones) were prepared for neutron scattering studies and for deuterium NMR investigations. The availability of these model macromolecules permits molecular-level identification of the motions responsible for the low temperature relaxations that have been observed in the dynamic mechanical spectra of these engineering polymers. Three labeled sites on the appropriate monomers (bisphenol-A and 4,4′-dichlorodiphenylsulfone) were prepared from deuterated intermediates and characterized via chromatographic, spectroscopic, and thermal analysis. The deuterium exhcange between methyl and aromatic sites that occurred during synthesis was quantified. These labeled monomers were mixed with hydrogenous monomers to synthesize high molecular weight, selectively deuterated poly(arylene ether sulfones). A synthetic technique involving N-methyl-2-pyrrolidone/potassium carbonate was employed to afford high molecular weight polymers. The polymers were characterized by FT-IR, proton, carbon, and deuterium NMR, intrinsic viscosities, and thermal analysis. Molecular weights of the labeled polymers were similar to unlabeled systems.     

Novel thermally stable poly(amine hydrazide)s and poly(amine‐1,3,4‐oxadiazole)s for luminescent and electrochromic materials

We describe the preparation, characterization, and luminescence of four novel electrochromic aromatic poly(amine hydrazide)s containing main‐chain triphenylamine units with or without a para‐substituted N,N‐diphenylamino group on the pendent phenyl ring. These polymers were prepared from either 4,4′‐dicarboxy‐4″‐N,N‐diphenylaminotriphenylamine or 4,4′‐dicarboxytriphenylamine and the respective aromatic dihydrazide monomers via a direct phosphorylation polycondensation reaction. All the poly(amine hydrazide)s were amorphous and readily soluble in many common organic solvents and could be solution‐cast into transparent and flexible films with good mechanical properties. These poly(amine hydrazide)s exhibited strong ultraviolet–visible absorption bands at 346–348 nm in N‐methyl‐2‐pyrrolidone (NMP) solutions. Their photoluminescence spectra in NMP solutions or as cast films showed maximum bands around 508–544 and 448–487 nm in the green and blue region for the two series of polymers. The hole‐transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. All obtained poly(amine hydrazide)s and poly(amine‐1,3,4‐oxadiazole)s exhibited two reversible oxidation redox couples at 0.8 and 1.24 V vs. Ag/AgCl in acetonitrile solution and revealed excellent stability of electrochromic characteristics, changing color from original pale yellow to green and then to blue at electrode potentials of 0.87 and 1.24 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3245–3256, 2005     

Preparation and properties of aromatic poly(amide–benzothiadiazine dioxides)

New thermostable poly(amide–benzothiadiazine dioxides) of high molecular weights have been prepared by the two-step cyclopolycondensation of diaminobenzenesulfonamides and aromatic bisacyl chlorides. In the first step, the low-temperature solution polymerization technique afforded open-chain polyamides (I) having high molecular weights. In the second step, the polymeric precursors (I) underwent chemical cyclodehydration in the presence of organic basic catalysts at 160°C to give poly(amide–benzothiadiazine dioxides) (II), whereas thermal cyclodehydration gave unsatisfactory results. Not only the open-chain polymers (I) but also the cyclized polymers (II) were soluble in polar solvents, such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone; tough films were cast from these solutions. Thermogravimetric analyses indicated that the cyclized polymers (II) began to decompose at 450–470°C under nitrogen or in air. It is interesting to note that both polymers I and II exhibited self-extinguishing properties against free flame. The cyclodehydration of model compounds was also investigated.     

Thermally stable sulfone-containing poly(amide-imides)

Novel sulfone containing poly(amide-imides) have been prepared by reacting 3,4-dicarboxy-4′-(chloroformyl)-diphenylsulfone dianhydride with various aromatic diamines. Relatively high molecular weight polymers were obtained by using a two-step procedure. Transparent poly(amide-imide) films, varying in color from dark yellow to colorless, were formed by thermally treating polyamic acid solutions. All films showed good thermal stability.     

Radiation degradation of poly(arylene ether ketone)s

The resistance of five poly(arylene ether ketone)s with related chemical structures to degradation by ionizing radiation has been studied by ESR spectroscopy and yields of volatile products. All of the polymers showed high resistance to radiation with low yields of radicals after irradiation in vacuum at 77 K (when up to 84% of the radicals were identified as radical anions) and much lower yields at 300 K. The yields of volatile products were much less than reported for poly(arylene sulfone)s [1, 2]. Methyl substitution on a main-chain aromatic ring decreased the radiation resistance, but methane only comprised 10% of the volatile products from the methyl-substituted polymers. A polymer containing an isopropylidene group in the main chain and a substituent aromatic carbonyl showed significantly decreased radiation resistance. Extremely low radical yields were obtained after irradiation in air at 300 K, contrary to many polymers. XPS analysis showed an increase in C–O bonds on the surface after irradiation in air.     

Investigation of thermodynamic properties of poly(methyl methacrylate-co-n-butylacrylate-co-cyclopentyl styryl-polyhedral oligomeric silsesquioxane) by inverse gas chromatography

The thermodynamic properties of poly(methyl methacrylate-co-butyl acrylate-co-cyclo -pentylstyryl polyhedral oligomeric silsesquioxane) (poly(MMA-co-BA-co-styryl-POSS)) were investigated by means of inverse gas chromatography (IGC) using 20 different kinds of solvents as the probes. Some thermodynamic parameters, such as molar heats of sorption, weight fraction activity coefficient, Flory-Huggins interaction parameter, partial molar heats of mixing and solubility parameter were obtained to judge the interactions between POSS-contained polymers and solvents and the solubility of the polymers in these solvents. It was found that acetates, aromatic hydrocarbons and hydrocarbon halides were good solvents, n-hexane, ethanol, n-propanol, n-butanol and n-pentanol were moderate solvents, while n-heptane, n-octane, n-nonane, n-decane and methanol were poor solvents for all POSS-contained polymers within the experimental temperature range. Incorporation of POSS in polymer increased the solubility of polymers in solvents, and the more the POSS in polymer was, the better the solubility was and stronger the hydrogen bonding interaction was, but the POSS content in polymers seemed to have no obvious influence on the solubility parameter of polymers.     

New thermally stable and organosoluble heterocyclic poly(naphthaleneimide)s

As majority of polyheteroarylenes based on bis(naphthalic anhydrides), are difficult to process due to their infusiblity and insolubility in common organic solvents and solubility only in strong acids, this study is concerned with the synthesis and properties of new, easily processable polyimides and copolyimides containing naphthalene and oxadiazole rings. These polymers have been synthesized and their properties have been compared with regard to the influence of oxadiazole and naphthalene units on their physical properties. The polyimides were prepared by polycondensation reaction in solution of the aromatic diamines containing preformed oxadiazole ring with two dianhydrides having naphthalene units, at high temperature. Also, copolyimides were prepared by using a mixture of each naphthalene‐containing dianhydride, with hexafluoroisopropylidene‐dianhydride in the polycondensation reaction with the same diamino‐oxadiazoles. Most of the resulting polyimides and copolyimides were soluble in polar amidic solvents and in less polar solvents, and their solutions gave flexible films when spread onto glass plates. The thermal stability and glass transition temperature of these polyimides and copolyimides were measured and compared. The quality and the roughness of the spin‐coated films of these polymers were investigated by atomic force microscopy. The photoluminescence properties of the polymers in solution were studied to determine the color of emission. The UV absorption was also studied to determine the Stokes shift, and hence the possible reabsorption effects. The properties of the present polyimides make them attractive for applications in advanced optoelectronics and other related fields. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and characterization of new fluorescent poly(arylene ether)s

The poly(arylene ether)s were prepared by the nucleophillic aromatic substitution polymerization of phenolphthalin and its derivatives with activated aromatic difluorides. The polymers had glass transition temperatures ranging from 210 to 240°C. Though the monomers have no fluorescence, the resulting polymers fluoresced a light green color in solid and solution states. The maximum excitation and emission wavelengths are 420 nm and 470 nm, respectively. In the polymer solutions, the fluorescence intensity decreased gradually, but the intensity was recovered by heating the polymer at 220°C for a few minutes. The fluorescent polymer had a stable radical. A model compound having the same repeating unit of the polymer was also prepared. The fluorescence properties of this model were almost the same as those of the polymers. © 1994 John Wiley & Sons, Inc.     

Unperturbed dimensions of poly(2-methyl-6-phenyl-1,4-phenylene oxide) and poly(2,6-diphenyl-1,4-phenylene oxide) chains

The unperturbed chain dimensions of unfractionated poly(2-methyl-6-phenyl-1,4-phenylene oxide) and poly-(2,6-diphenyl-1,4-phenylene oxide) have been measured by combining molecular weight data from light scattering with intrinsic viscosity data in chloroform. The unperturbed chain dimensions of the former polymer were also measured directly by light scattering dissymmetry in a critical consolute solvent mixture (methyl cyclohexane: 1,4-dioxane 50:50 by volume). The results of these measurements and of measurements reported by other investigators are satisfactorily explained by postulating no dimension-expanding prejudice in azimuthal angle in chain conformers of the 2,6-substituted-1,4-phenylene oxide polymers. This corresponds to equal population of the two chain rotation energy minima at azimuthal angles 90° and 270°. Accepting this postulate, one calculates from the observed chain dimensions that the C? O? C bond angle is 118–120° in these aromatic polyethers in solution.     

New poly(amide-lmide)s syntheses. XV. Preparation and properties of poly(amide-imide)s derived from 9, 9-bis[4-(4-aminophenoxy) phenyl]fluorene and various bis(trimellitimide)s

Fifteen bis(phenoxy) fluorene-containing poly(amide-imide)s III were synthesized by the direct polycondensation of 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene (BAPPF) with var-ious aromatic bis(trimellitimide)s II in N-methyl-2-pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Poly(amide-imide)s III having inherent vis-cosities up to 1.45 dL/g were obtained in quantitative yields. Most of the resulting polymers showed an amorphous nature and were readily soluble in polar solvents such as NMP and N,N-dimethylacetamide. All the soluble poly(amide-imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range of 263–315°C and the 10% weight loss temperatures were above 510°C in nitrogen. Some properties of poly(amide-imide)s III were compared with those of the corresponding isomeric poly(amide-imide)s III ′ prepared from 9,9-[4-(4-trimellitimidophenoxy)phenyl]fluorene and various aromatic diamines. © 1995 John Wiley & Sons, Inc.     

Synthesis of poly(1,3,4-oxadiazole)s by direct polycondensation of dicarboxylic acids with hydrazine sulfate using phosphorus pentoxide/methanesulfonic acid as condensing agent and solvent

A convenient method for the synthesis of poly(1,3,4-oxadiazole)s of high molecular weights has been developed. These polymers were prepared readily by the direct polycondensation of dicarboxylic acids with hydrazine sulfate ( 1 ) using phosphorus pentoxide/methanesulfonic acid (PPMA) as both a condensing agent and solvent. Polycondensation of aliphatic dicarboxylic acids with 1 proceeded even at room temperature and produced poly(1,3,4-oxadiazole)s with inherent viscosities up to 1.4 dL/g. The synthesis of aromatic poly(1,3,4-oxadiazole)s from aromatic dicarboxylic acids containing phenyl ether structures was carried out by a one-pot procedure because the preactivation of dicarboxylic acids was required. The synthesis of 2,5-disubstituted-1,3,4-oxadiazoles by the reaction of carboxylic acids with 1 in PPMA was studied to demonstrate the feasibility of the reaction for polymer formation. The thermogravimetry of the aromatic poly(1,3,4-oxadiazole)s showed 10% weight loss both in air and in nitrogen at 440–490°C.     

Synthesis and characterization of poly(arylene ether imidazole)s

Poly(arylene ether imidazole)s were prepared by the aromatic nucleophilic displacement reaction of a bisphenol imidazole with activated aromatic dihalides. The polymers had glass transition temperatures ranging from 230 to 318°C and number-average molecular weights as high as 82,000 g/mol. Thermogravimetric analysis showed a 5% weight loss occurring ～ 400°C in air and ～ 500°C in nitrogen. Typical neat resin mechanical properties obtained at room temperature included tensile strength and tensile modulus of 14.2 and 407 ksi and fracture energy (G_lc) of 23 in. lb/in.² Titanium-to-titanium tensile shear strengths measured at 23 and 200°C were 4800 and 3000 psi, respectively. In addition, preliminary data were obtained on carbon fiber laminates. The chemistry, physical, and mechanical properties of these polymers are discussed.     

Poly(1,3,4-oxadiazole-amide)s containing pendent imide groups

A series of new poly(1,3,4-oxadiazole-amide)s containing pendent imide groups has been synthesized by solution polycondensation of aromatic diamines containing preformed 1,3,4-oxadiazole rings with two diacid chlorides containing imide rings. These polymers were also prepared by the reaction of the same diacid chlorides with p-aminobenzhydrazide which were subsequently cyclodehydrated in solid state. The polymers were soluble in polar amidic solvents and some of them gave transparent flexible films by casting from solutions. They showed high thermal stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 245–327°C. They had low dielectric constants, in the range of 3.32–3.94, and good tensile properties.