Synthesis and characterization of novel wholly para‐oriented aromatic polyamide‐hydrazides containing sulfone‐ether linkages

Four novel wholly para‐oriented aromatic polyamide‐hydrazides containing flexibilizing sulfone‐ether linkages in their main chains have been synthesized from 4‐amino‐3‐hydroxy benzhydrazide (4A3HBH) with either 4,4′‐sulfonyldibenzoyl chloride (SDBC), 4,4′‐[sulfonylbis(1,4‐phenylene)dioxy]dibenzoyl chloride (SODBC), 4,4′‐[sulfonylbis(2,6‐dimethyl‐1,4‐phenylene)dioxy]dibenzoyl chloride (4MeSODBC), or 4,4′‐(1,4‐phenylenedioxy)dibenzoyl chloride (ODBC) via a low‐temperature solution polycondensation reaction. A polyamide‐hydrazide without the flexibilizing linkages is also investigated for comparison. It was synthesized from 4A3HBH and terephthaloyl chloride (TCl) by the same synthetic route. The intrinsic viscosities of the polymer ranged from 2.85 to 4.83 dL g^?1 in N,N‐dimethyl acetamide (DMAc) at 30°C and decreased with introducing the flexibilizing linkages into the polymer. All the polymers were soluble in DMAc, N,N‐dimethyl formamide (DMF), and N‐methyl‐2‐pyrrolidone (NMP), and their solutions could be cast into films with good mechanical strengths. Further, they exhibited a great affinity to water sorption. Their solubility and hydrophilicity increased remarkably by introducing the flexibilizing linkages. The polymers could be thermally cyclodehydrated into the corresponding poly(1,3,4‐oxadiazolyl‐benzoxazoles) approximately in the region of 295–470°C either in nitrogen or in air atmospheres. The flexibilizing linkages improve the solubility of the resulting poly(1,3,4‐oxadiazolyl‐benzoxazoles) when compared with poly(1,3,4‐oxadiazolyl‐benzoxazoles) free from these linkages. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of novel poly(aryl ether ketone)s containing imide linkages in the main chains

A new monomer containing imide linkages, bis[4-(p-phenoxybenzoyl)-1,2-benzenedioyl]-N,N,N′,N′-4,4′-diaminodiphenyl ether (BPBDADPE), was prepared by the Friedel–Crafts reaction of bis(4-chloroformyl-1,2-benzenedioyl)-N,N,N′,N′-4,4′-diaminodiphenyl ether (BCBDADPE) with diphenyl ether (DPE). Novel poly(aryl ether ketone)s containing imide linkages in the main chains (PEK-I) were synthesized by electrophilic Friedel–Crafts solution copolycondensation of terephthaloyl chloride (TPC) with a mixture of DPE and BPBDADPE. The polymers were characterized by different physico-chemical techniques. The polymers with 10–40 mol% BPBDADPE are semicrystalline and had increased T _gs over commercially available poly(ether ether ketone) (PEEK) and poly(ether ketone ketone) (PEKK) (70/30) due to the incorporation of imide linkages in the main chains. The polymers IV and V with 30–40 mol% BPBDADPE had not only high T _gs of 182–183 °C, but also moderate T _ms of 341–343 °C, having good potential for melt processing and exhibited high thermal stability and good resistance to common organic solvents.     

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s have been prepared by solution polycondensation reaction of different aromatic diamines having preformed 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, 2,5-bis[p-(3-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2-(4-dimethylaminophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole and 2-(4-fluorophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole, with an aromatic dianhydride incorporating ether linkages and hexafluoroisopropylidene group, namely 1,1,1,3,3,3-hexafluoro-2,2-bis-[(3,4-dicarboxyphenoxy)phenyl]-propane dianhydride. The polymers were easily soluble in polar organic solvents, such as N-methylpyrrolidinone, N,N-dimethylformamide, and pyridine, as well as in certain low boiling-point organic solvents, such as tetrahydrofuran and chloroform. Very thin coatings deposited onto silicon wafers exhibited smooth, pinhole-free surface in atomic force microscopy. The polymers showed high thermal stability with decomposition temperature being above 410 °C. They exhibited a glass transition in the temperature range of 183-217 °C, with reasonable interval between glass transition and decomposition temperature. Solutions of some polymers in N,N-dimethylformamide exhibited blue fluorescence, having maximum emission wavelength in the range of 411-424 nm.     

Synthesis and characterization of polyamides and poly(amide-imide)s based on ether-sulfone-diamines

A series of polyamides and poly(amide-imide)s were prepared by the direct polycondensation of 4,4′-[sulfonylbis(1,4-phenyleneoxy)]dianiline or 4,4′-[sulfonylbis(2,6-dimethyl-1,4-phenyleneoxy)]dianiline with aromatic dicarboxylic acids and phthalimide unit-bearing dicarboxylic acids in a N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride using triphenyl phosphite and pyridine as condensing agents. The inherent viscosities of the resulting polymers were above 0.45 dL/g and up to 1.70 dL/g. Except for the polyamides derived from terephthalic acid and 4,4′-biphenyldicarboxylic acid, all the other polyamides and all poly(amide-imide)s were readily soluble in polar organic solvents such as NMP, N, N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and m-cresol, and afforded transparent and tough films by solution-casting. Most of the polymers showed distinct glass transition on their differential scanning calorimetry (DSC) traces and their glass transition temperatures (T_g) stayed between 140–264 °C. The methyl-substituted polymers showed higher T_gs than the corresponding unsubstituted counterparts. The results of the thermogravimetry analysis (TGA) revealed that all the methyl-substituted polymers showed lower initial decomposition temperatures than the unsubstituted ones.     

A new rigid rodlike colored poly(amide hydrazide): Thermal,optical anisotropic,and mechanical behavior

A new aromatic all-para oriented poly(amide hydrazide) containing an azo group in the main chain was prepared by reacting a symmetric diamine containing a preformed hydrazide group, viz., N,N′-bis(4-aminobenzoyl)hydrazine (BABH), with 4,4′-azobenzoyl chloride (ADBC). The thermal behavior of the polymer was studied by TGA and DSC in air and nitrogen. Films of the polymer were prepared by two processes, viz., wet and dry processes, by using its solution in DMAc containing LiCl. The optical anisotropy, surface morphology, and tensile properties of the films were studied. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1211–1215, 1997     

Novel Ferrocene-Based Organometallic Poly(ether sulfone amide imide)s: Preparation, Characterization, and Properties

A new ferrocene-based diamine (ESAFDA) with built-in ether, sulfone, and amide groups was prepared via reaction of two synthetic precursors. Firstly, 1,1′-ferrocenedicarbonyl chloride was prepared from 1,1′-ferrocenedicarboxylic acid using oxalyl chloride. In another reaction, nucleophilic substitution reaction of 3-aminophenol with bis(4-chlorophenyl sulfone) was used for synthesis of 3,3′-(4,4′-sulfonyl bis(1,4-phenylene) bis (oxy)) dianiline (SBOD). Finally, the diamine was prepared via nucleophilic reaction of SBOD with 1,1′-ferrocenedicarbonyl chloride. The precursors and the diamine were characterized by conventional methods and the diamine was used for preparation of different ferrocene-based poly(ether sulfone amide imide)s through polycondensation with three different dianhydrides. The polymers were characterized by elemental analysis, FTIR and ¹H-NMR spectroscopy. Various properties of the polymers including inherent viscosity, molecular weight, solubility, thermal stability and behavior, flame-retardant nature, mechanical properties, and crystallinity were studied. Presence of ferrocene structure in companion to ether, sulfone, and amide units in the backbone of polyimides led to improved solubility of the polymers in polar aprotic solvents and enhanced thermal stability and flame-retardant character of polyimides.     

Crosslinkable poly(aryl ether ketone)s containing pendant phenylethynyl moieties: Synthesis, characterization and properties

A novel phenylethynyl-contained bisphenol monomer, (2,5-dihydroxyphenyl)(4-(2-phenylethynyl)phenyl)methanone (PEBP), has been synthesized and characterized. The resultant monomer was copolymerized with hydroquinone and 4,4′-difluorobenzophenone by means of an aromatic nucleophilic substitution reaction to provide a series of crosslinkable poly(aryl ether ketone)s containing pendant phenylethynyl moieties (PE-PAEKs). The solubility of PE-PAEKs tended to be improved with the increase in PEBP content. Wide-angle X-ray diffraction (WAXD) results showed that introduction of bulky pendant groups into molecular chains led to decrease in crystallinity. PE-PAEKs were successfully cured upon heating. Dynamic mechanical analysis (DMA) results indicated that the glass-transition temperature (T_g) of the cured PE-PAEKs was increased. Thermogravimetric analysis (TGA) results implied that the thermal stability of the cured PE-PAEKs was excellent.     

Aliphatic-aromatic poly(ester-imide)s from diisocyanates containing ester groups and aromatic dianhydrides

Summary Four new ester group containing diisocyanates, viz., 3,3′-(glutaryldioxy)diphenyl diisocyanate, 4,4′-(glutaryldioxy)diphenyl diisocyanate, 3,3′-(adipoyldioxy)diphenyl diisocyanate, and 4,4′-(adipoyldioxy)diphenyl diisocyanate were synthesized from the corresponding dicarboxylic acids via the Curtius rearrangement reaction. These diisocyanates were polycondensed with pyromellitic dianhydride (PMDA) and benzo-phenonetetracarboxylic dianhydride (BTDA) in dimethylacetamide to yield eight aliphatic-aromatic polyimides containing ester groups in the backbone with inherent viscosities in the range 0.25–0.70 dL/g. These poly(ester-imide)s were semicrystalline in nature and exhibited no weight loss below 300°C in air. N.C. L. Commun. No. 5330     

New aromatic poly(ether-ketone)s containing hexafluoroisopropylidene groups

Summary New aromatic poly(ether-ketone)s containing hexafluoroisopropylidene groups have been prepared by aromatic nucleophylic displacement reaction of the potassium salts of aromatic dihydroxy compounds containing fluoren, 1,3,4-oxadiazole or phenylquinoxaline rings with 2,2-bis[4-(4-fluorobenzoylphenyl)hexafluoropropane. These polymers were readily soluble in various organic solvents such as N,N-dimethylformamide, pyridine, tetrahydrofuran and chloroform and gave flexible films by casting such solutions. Their glass transition temperatures (T_g) were in the range of 189–222°C and they were thermally stable up to 480°C. The polymer films displayed low dielectric constants, in the range of 2.8 – 3.2, and good mecanical properties, with tensile strength in the range of 46 – 61 MPa and elastic modulus of 1.4 – 1.6 GPa. Received: 6 April 2001/Revised version: 31 July 2001/Accepted: 31 July 2001     

Synthesis and characterization of new poly(arylene ether 1,3,4-oxadiazole)s based on dihydroxynaphthalene isomers

Summary A series of new poly(arylene ether 1,3,4-oxadiazole)s has been obtained starting from a difluorosubstituted monomer containing 1,3,4-oxadiazole rings and some dihydroxynaphthalene isomers. The polymers have been prepared by polycondensation in solution and have been obtained in quantitative yield. They had inherent viscosity from 0.2 to 0.82 dL/g, showed good thermal stability (10% weight loss temperatures in nitrogen and air were above 460 and 450°C, respectively) and high glass transition temperatures (in the range of 197–232°C). The polymers were characterized by elemental and infrared analyses, GPC and wide angle X-ray diffraction. Received: 27 June 2000/Revised version: 2 October 2000/Accepted: 2 October 2000     

Covalently and ionically crosslinked sulfonated poly(arylene ether ketone)s as proton exchange membranes

A series of covalently and ionically crosslinked sulfonated poly(arylene ether ketone)s (SPAEKs) were prepared via the cyclocondensation reaction of crosslinkable SPAEKs with 3,3′-diaminobenzidine to form quinoxaline groups, where crosslinkable SPAEKs were synthesized by copolymerization of 4,4′-biphenol with 2,6-difluorobenzil, 4,4′-difluorobenzophenone, and 5,5′-carbonyl-bis(2-fluorobenzene sulfonate). The SPAEK membranes had high mechanical properties and the isotropic membrane swelling. The covalent and ionical crosslinking significantly improved the membrane performance, i.e., the crosslinked membranes showed the lower membrane dimensional change, lower methanol permeability, and higher oxidative stability than the corresponding uncrosslinked membranes, with keeping the reasonably high proton conductivity. The crosslinked membrane (CK3) with measured ion exchange capacity of 1.62 mequiv g⁻¹ displayed a reasonably high proton conductivity of 110 mS/cm with water uptake of 33 wt% at 80 °C, and exhibited a low methanol permeability of 1.7 × 10⁻⁷ cm² s⁻¹ for 32 wt% methanol solution at 25 °C. The covalently and ionically crosslinked SPAEK membranes have potential for polymer electrolyte membrane fuel cells and direct methanol fuel cells.     

Synthesis and characterization of novel sulfonated poly(arylene ether ketone)s derived from 4,4'-sulfonyldiphenol

Summary Novel sulfonated poly(arylene ether ketone)s were prepared directly by aromatic nucleophilic polycondensation of 4,4'-sulfonyldiphenol with various ratios of 4,4'-difluorobenzophenone to 5,5'-carbonylbis(2-fluorobenzenesulfonate) in dimethyl sulfoxide. The resulting polyelectrolytes were characterized by IR, NMR, TGA and DSC. The 10% weight loss temperature of the products is higher than 510°C, and their glass transition temperature is above 260°C. The introduction of 4,4'-sulfonyldiphenol with powerful electron-withdrawing group, -SO₂₋, into the main chain of sulfonated poly(arylene ether ketone)s improves the thermal stability against desulfonation. The ion-exchange capacity and swelling of the polyelectrolyte membranes were measured, which are higher than 1.23meq/g and not higher than 20.9%, respectively. The membranes show very good perspectives in polymer electrolyte fuel cell (PEMFC) application. Received: 27 March 2002 / Revised version: 7 May 2002 / Accepted: 13 May 2002     

Synthesis of new diacid monomers and poly(amide-imide)s: study of structure–property relationship and applications

Two diimide-diacid monomers 4,4′-bis[4″-(trimellitimido)phenyl isopropylidene-4″′-phenoxy]diphenyl sulfone and 4,4′-bis[4″-(trimellitimido)phenylisopropylidene-4″′-phenoxy] were synthesized. The structures of the monomers were characterized by FT-IR and ¹H-NMR spectroscopy. A series of novel poly(amide-imide)s were prepared from this two diacids and aromatic diamines through phosphorylation reaction. The PAIs were characterized by FT-IR, ¹H-NMR, XRD, TGA, and DSC, solution viscosity, solubility test and electrical properties. Poly(amide-imide)s showed excellent solubility due to the presence of flexible groups and isopropylidene unit in the polymer backbone. They also exhibited good thermal stability and the temperatures at which 10% weight loss occurred in the range 385–465 °C. These PAIs found to have a dielectric constant in the range 3.25–4.20 at 10 kHz and have excellent electrical insulation character and can be used as insulation materials for electrical items operating at elevated temperatures.     

Synthesis and characterization of new cardo poly(ether imide)s derived from 9,9‐bis [4‐(4‐aminophenoxy)phenyl]xanthene

A series of new cardo poly(ether imide)s bearing flexible ether and bulky xanthene pendant groups was prepared from 9,9‐bis[4‐(4‐aminophenoxy)phenyl]xanthene with six commercially available aromatic tetracarboxylic dianhydrides in N,N‐dimethylacetamide (DMAc) via the poly(amic acid) precursors and subsequent thermal or chemical imidization. The intermediate poly(amic acid)s had inherent viscosities between 0.83 and 1.28 dL/g, could be cast from DMAc solutions and thermally converted into transparent, flexible, and tough poly(ether imide) films which were further characterized by X‐ray and mechanical analysis. All of the poly(ether imide)s were amorphous and their films exhibited tensile strengths of 89–108 MPa, elongations at break of 7–9%, and initial moduli of 2.12–2.65 GPa. Three poly(ether imide)s derived from 4,4′‐oxydiphthalic anhydride, 4,4′‐sulfonyldiphthalic anhydride, and 2,2‐bis(3,4‐dicarboxyphenyl))hexafluoropropane anhydride, respectively, exhibited excellent solubility in various solvents such as DMAc, N,N‐dimethylformamide, N‐methyl‐2‐pyrrolidinone, pyridine, and even in tetrahydrofuran at room temperature. The resulting poly(ether imide)s with glass transition temperatures between 286 and 335°C had initial decomposition temperatures above 500°C, 10% weight loss temperatures ranging from 551 to 575°C in nitrogen and 547 to 570°C in air, and char yields of 53–64% at 800°C in nitrogen. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of polyimides based on isopropylidene-containing bis(ether anhydride)s

Two bis(ether anhydride)s, 4,4′-[1,4-phenylenebis(isopropylidene-1,4-phenyleneoxy)]-diphthalic anhydride (IV _a) and 4,4′-[isopropylidenebis(1,4-phenylene)dioxy]diphthalic anhydride (IV _b), were prepared in three steps starting from the nucleophilic nitrodisplacement reaction of 4-nitrophthalonitrile with α,α ′-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene (I _a) and 4,4′-isopropylidenediphenol (I _b) in N,N-dimethylformamide (DMF) in the presence of potassium carbonate. The bis(ether anhydride)s IV _a and IV _b were polymerized with various aromatic diamines to obtain two series of poly(ether amic acid)s VI _a–g and VII _a–g with inherent viscosities in the range of 0.30∼0.74 and 0.29∼1.01 dL/g, respectively. The poly(ether amic acid)s were converted to poly(ether imide)s VIII _a–g and IX _a–g by thermal cyclodehydration. Most of the poly(ether imide)s could afford flexible and tough films, and they showed high solubility in polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, and m-cresol. The obtained poly(ether imide) films had tensile strengths of 45∼83 MPa, elongations-to-break of 6∼27%, and initial modulus of 0.6∼1.7 GPa. The T_gs of poly(ether imide)s VIII _a–g and IX _a–g were in the range of 194∼210 and 204∼243 °C, respectively. Thermogravimetric analysis (TG) showed that 10% weight loss temperatures of all the polymers were above 500 °C in both air and nitrogen atomspheres.     

Synthesis, characterization, and crosslinking of soluble cyano-containing poly(arylene ether)s bearing phthalazinone moiety

A novel series of phthalazinone-based poly(arylene ether nitrile)s bearing terminal cyano groups via N-C linkages (PPEN-DCs) were synthesized by a simple solution polycondensation of 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one (HPPZ) with calculated 2,6-difluorobenzonitrile (DFBN), followed by the termination of 4-chlorobenzonitrile (CBN). The M_ns of oligomeric PPEN-DCs, which are in the range of 1600-6200, can be well-controlled by adjusting reactant ratio. The incorporation of phthalazinone into the polymer chain results in an improvement in the solubility and glass transition temperatures (T_gs). The amorphous PPEN-DCs were thermally crosslinked to afford insoluble products in the presence of terephthalonitrile and zinc chloride. The pendant cyano groups in the polymer chain hardly undergo any crosslinking or cyclization, while the terminal cyano groups with nitrogen-bridged phthalazinone in the para-substitution are much more reactive in s-triazine forming reaction and effectively promote certain crosslinking under normal pressure. T_gs of the oligomers, which range from 245 to 269 °C, could be further increased at least by 94 °C upon thermal curing. The crosslinked samples exhibit excellent thermal stability and absorb less than 2.7 wt% water after exposure to an aqueous environment for extended periods. This kind of cyano-terminated poly(arylene ether nitrile)s may be a good candidate as matrix resins for high-performance polymeric materials.     

A novel synthesis of reactive polyethers with pendant chloromethyl group by polyaddition of bis(epoxide)s with aromatic dichlorides

New polyethers with pendant chloromethyl groups were successfully synthesized by a polyaddition of bisepoxides with 4,4′-dichloro-3,3′-dinitrodiphenyl sulfone (DCNS) using quaternary onium salts or crown ether complexes as catalysts. The polyaddition of DCNS with diglycidyl ether of bisphenol A (DGEBA) was enhanced efficiently by the addition of tetrabutylammonium chloride (TBAC), tetrabutylammonium bromide (TBAB), or tetrabutylphosphonium chloride (TBPC) as catalysts. It was also found that the reaction proceeded smoothly in amide-type polar solvents such as N,N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) to give a high molecular weight polyether P-1. The polyaddition of DCNS with diglycidyl ether of ethylene glycol (DGEEG) using TBAB in DMAc also proceeded to give the polyether P-2 in good yield. The resulting polyethers contain reactive chloromethyl groups in a side chain, which was introduced during main chain formation.     

Preparation and characterization of ordered thin films based on aromatic poly(1,3,4-oxadiazole)s

Ultrathin layers of aromatic polyoxadiazoles by using the Langmuir-Blodgett technique are prepared for the first time. The syntheses and characterization of new soluble aromatic poly(1,3,4-oxadiazole)s are described. The polyoxadiazoles contain tetraphenyl silane units in the main chain or pendent alkylamido groups. Both the precursor route via polyhydrazide followed by thermal cyclization in bulk, and the direct spreading of poly(1,3,4-oxadiazole)s are used for film forming. The supramolecular structures of all ordered poly(arylene-1,3,4-oxadiazole) LB films are characterized by FTIR spectroscopy, X-ray scattering and atomic force microscopy, respectively.     

The synthesis and thermotropic liquid crystalline behavior of the novel poly(aryl ether ketone)s containing chloro-side group

The novel poly(aryl ether ketone)s containing chloro-side group were synthesized by nucleophilic substitution reactions of 4,4′-biphenol and chlorohydroquinone with either 4,4′-difluorobenzophenone (BP/CH/DF) or 1,4-bis(p-fluorobenzoyl)benzene (BP/CH/BF) and their thermotropic liquid crystalline properties were characterized by a variety of experimental techniques. The thermotropic liquid crystalline behavior was observed in the copolymers containing 50 and 70% biphenol. Melting transition (Tm) and isotropization transition (Ti) both appeared in the DSC thermograms. A banded texture was formed after shearing the sample in the liquid crystalline state. The novel poly(aryl ether ketone)s had relatively higher glass transition temperature (Tg) in the range of 168 ∼ 200 °C and lower melting temperature (Tm) in the range of 290 ∼ 340 °C. The thermal stability (Td) was in the range of 430 ∼ 490 °C. Received: 7 February 1997/Revised: 31 March 1997/Accepted: 2 April 1997     

Novel poly(amide‐hydrazide)s and copoly(amide‐hydrazide)s from bis‐(4‐aminobenzyl) hydrazide and aromatic diacid chlorides: Synthesis and characterization

A new aromatic diamine, viz., bis‐(4‐aminobenzyl) hydrazide (BABH), which contains preformed hydrazide and methylene linkage, was synthesized starting from α‐tolunitrile. The BABH and intermediates involved in its synthesis were characterized by spectroscopic methods. Novel poly(amide‐hydrazide)s were synthesized by low temperature solution polycondensation of BABH with isophthaloyl chloride (IPC) and terephthaloyl chloride (TPC). Furthermore, two series of copoly(amide‐hydrazide)s, based on different mol % of BABH and bis‐(4‐aminophenyl) ether (ODA) with IPC/TPC were also synthesized. Poly(amide‐hydrazide)s and copoly(amide‐hydrazide)s were characterized by inherent viscosity [η_inh], FTIR, solubility, X‐ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polycondensation proceeded smoothly and afforded the polymers with inherent viscosities in the range of 0.18–0.93 dL/g in (NMP + 4% LiCl) at 30°C ± 0.1°C. These polymers dissolved in DMAc, NMP or DMSO containing LiCl. The solubility of copolymers was considerably improved in line with less crystalline nature due to random placement of constituent monomers during the copolymerization. XRD data indicated that poly(amide‐hydrazide)s from BABH alone and IPC/TPC had higher crystallinity than the corresponding copoly(amide‐hydrazide)s derived from a mixture of BABH and bis‐(4‐aminophenyl) ether (ODA). Polymers showed initial weight loss around 160°C which is attributed to the cyclodehydration leading to the formation of corresponding poly(amide‐oxadiazole)s. Copolyamide‐hydrazides showed T_max between 400 and 540°C which is essentially the decomposition of poly(amide‐oxadiazole)s. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010