New polymer syntheses. 107. Aliphatic poly(thio ester)s by ring‐opening polycondensation of 2‐stanna‐1,3‐dithiacycloalkanes

We prepared 2,2‐dibutyl‐2‐stanna‐1,3‐dithiacycloalkanes from dibutyltin oxide and α,ω‐dimercaptoalkanes. Heterocycles with five‐, six‐, seven‐, or nine‐ring members were used as bifunctional monomers for polycondensations with aliphatic dicarboxylic acid chlorides. These polycondensations conducted in bulk were highly exothermic and yielded poly(thio ester)s with number average molecular weights (M_n's) in the range of 5000–30,000 Da. These poly(thio ester)s proved to be rapidly crystallizing materials with melting temperatures in the range of 90–150 °C. In addition to the success of the new synthetic approach, two interesting and unpredictable results were obtained. All volatile species detectable by matrix assisted laser desorption induced‐time of flight (MALDI‐TOF) mass spectrometry were cyclic oligo‐ and poly(thio ester)s. Second, several polyesters showed a reversible first‐order change of the crystal modification as identified by differential scanning calorimetry measurements and X‐ray scattering with variation of the temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3656–3664, 2000     

Syntheses of trimethoxysilyl‐endcapped polylactones via 3‐mercaptopropyl trimethoxysilane

Monofunctional polylactones were prepared by Bu₂Sn(OMe)₂‐initiated ring‐opening polymerization of ε‐caprolactone (εCL) followed by acylation with bromoacetylbromide. Telechelic polylactones and polylactides were prepared via ring‐expansion polymerization with 2,2‐dibutyl‐2‐stanna‐1,3‐dioxepane (DSDOP) or 2,2‐dibutyl‐2‐stanna‐pentaoxacyclotridecane (Bu₂SnTEG) as cyclic initiator. In situ combination of the polymerization with condensation by means of bromoacetylbromide yielded polylactones having bromoacetate endgroups. These endgroups were subjected to nucleophilic substitution with 3‐mercaptopropyl trimethoxysilane (3‐MPTMS). Analogous experiments were conducted with dl‐lactide. The telechelic trimethoxysilyl‐endcapped polylactones were characterized by viscosity, ¹H and ¹³C NMR‐spectroscopy, and MALDI‐TOF mass spectrometry. The mass spectra revealed small amounts of cyclic oligolactones as byproducts in all samples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3667–3674, 2005     

Cyclic poly(lactide)s via the ROPPOC method catalyzed by alkyl‐ or aryltin chlorides

A comparison of tributyltin chloride, dibutyltin dichloride, and butyltin trichloride as catalysts of ring‐opening polymerizations (ROPs) of l‐lactides at 160 °C in bulk reveals increasing reactivity in the above order, but only the least reactive catalysts, Bu₃SnCl, yield a uniform reaction product, namely cyclic poly(L‐lactide)s with weight average molecular weights (M_w's) in the range of 40,000–80,000. A comparison of dimethyltin , dibutyltin , and diphenyltin dichlorides resulted in the following order of reactivity: Me₂SnCl₂ < Bu₂SnCl₂ < <Ph₂SnCl₂. In this series also, the most reactive catalyst yields cyclic polylactides, but the extent of cyclization varies with the molecular weight. The formation of cyclic polylactides is explained by ROP combined with simultaneous polycondensation involving end‐to‐end cyclization (ROPPOC method). ROP of meso‐lactide at 80 or 60 °C yields even‐numbered linear chains as main products, a result supporting the ROPPOC mechanism. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 952–960     

Synthesis and properties of poly(amic acid)s and polyimides based on 2,2′,6,6′‐biphenyltetracarboxylic dianhydride

Poly(amic acid)s (PAAs) having the high solution stability and transmittance at 365 nm for photosensitive polyimides have been developed. PAAs with a twisted conformation in the main chains were prepared from 2,2′,6,6′‐biphenyltetracarboxylic dianhydride (2,2′,6,6′‐BPDA) and aromatic diamines. Imidization of PAAs was achieved by chemical treatment using trifluoroacetic anhydride. Among them, the PAA derived from 2,2′,6,6′‐BPDA and 4,4′‐(1,3‐phenylenedioxy)dianiline was converted to the polyimide by thermal treatment. The heating at 300 °C under nitrogen did not complete thermal imidization of PAAs having glass‐transition temperatures (T_g)s higher than 300 °C to the corresponding PIs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6385–6393, 2006     

Cyclic polylactides via simultaneous ring‐opening polymerization and polycondensation catalyzed by dibutyltin mercaptides

l ‐Lactide is polymerized in bulk at 160 °C either with dibutyltin bis(benzylmercaptide) (SnSBzl), dibutyltin bis(benzothiazole 2‐mercaptide) (SnMBT), or with dibutyltin bis(pentafluorothiophenolate) (SnSPF) as catalysts. SnSBzl yields linear polylactides having benzylthio‐ester end groups in addition to cyclic polylactides, whereas SnMBT and SnSPF mainly or exclusively yield cyclic polylactides. This finding, together with model reactions, indicates that the SnS catalysts promote a combined ring‐opening polymerization and polycondensation process including end‐to‐end cyclization. SnMBT caused slight racemization (3%–5%), when used at 160 °C. With SnSPF optically pure cyclic poly(l ‐lactide)s with high‐molecular weights can be prepared at 160 °C. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3767–3775     

Novel thermally latent self‐crosslinkable copolymers bearing oxetane and hemiacetal ester moieties: The synthesis,self‐crosslinking behavior,and thermal properties

Novel thermally latent self‐crosslinkable copolymers ( 14 and 15 ) containing hemiacetal ester and oxetane moieties were synthesized by the radical copolymerizations of 1‐propoxyethyl methacrylate, 3‐ethyl‐3‐methacryloyloxymethyl oxetane, and/or n‐butyl methacrylate at 60 °C in the presence of 2,2′‐azoisobutylonitrile as an initiator. The obtained copolymers showed good solubility for common organic solvents such as tetrahydrofuran, chloroform, and dimethyl sulfoxide (DMSO). The thermal crosslinking behaviors were examined with several Lewis acid catalysts ( 6 ). In particular, the treatment with aluminum‐2‐ethylhexanate triethanolamine complex ( 6c ) at 160 °C was found to efficiently yield the corresponding self‐crosslinked polymers ( 14′ and 15′ ). Incidentally, the resulting products were hardly insoluble in various organic solvents, including DMSO. The thermal properties of the obtained self‐crosslinked polymers 14′ and 15′ were estimated by thermogravimetric analysis and differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4260–4270, 2005     

Synthesis and properties of novel soluble poly(amide‐imide)s with different pendant substituents

Two types of novel fluorinated diimide‐diacid monomers—[2,2′‐(4,4′‐(3′‐methylbiphenyl‐2,5‐diyl)bis(oxy)bis(3‐(trifluoromethyl)‐4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid)] (III) and [2,2′‐(4,4′‐(3′‐(trifluoromethyl)biphenyl‐2,5‐diyl)bis(oxy)bis(3‐(trifluoromethyl)‐4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid)] (IV)—were respectively designed and prepared by the condensation of diamines I and II with two molar equivalents of trimellitic anhydride. From both diimide‐diacids, two series of novel poly(amide‐imide)s (PAIs) (IIIa–IIIe and IVa–IVe) bearing different pendant groups were prepared by direct polymerization with various aromatic diamines (a–e). All the PAIs had a high glass transition temperatures (T_gs, 232–265 °C), excellent thermal stability (exhibiting only 5% weight loss at 493–542 °C under nitrogen) and good solubility in various organic solvents due to the introduction of the bulky pendant groups. The cast films of these PAIs (80–90 μm) had good optical transparency (73–81% at 450 nm, 85–88% at 550 nm and 87–89% at 800 nm) and low dielectric constants (2.65–2.98 at 1 MHz). The spin‐coated films of these PAIs presented a minimum birefringence value as low as 0.0077–0.0143 at 650 nm and low optical absorption at the near‐infrared optical communication wavelengths of 1310 and 1550 nm. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3243–3252     

Synthesis and properties of aromatic polyimides derived from 2,2,′3,3′‐biphenyltetracarboxylic dianhydride

2,2,′3,3′‐Biphenyltetracarboxylic dianhydride (2,2,′3,3′‐BPDA) was prepared by a coupling reaction of dimethyl 3‐iodophthalate. The X‐ray single‐crystal structure determination showed that this dianhydride had a bent and noncopolanar structure, presenting a striking contrast to its isomer, 3,3,′4,4′‐BPDA. This dianhydride was reacted with aromatic diamines in a polar aprotic solvent such as N,N‐dimethylacetamide (DMAc) to form polyamic acid intermediates, which imidized chemically to polyimides with inherent viscosities of 0.34–0.55 dL/g, depending on the diamine used. The polyimides from 2,2,′3,3′‐BPDA exhibited a good solubility and were dissolved in polar aprotic solvents and polychlorocarbons. These polyimides have high glass transition temperatures above 283°C. Thermogravimetric analyses indicated that these polyimides were fairly stable up to 500°C, and the 5% weight loss temperatures were recorded in the range of 534–583°C in nitrogen atmosphere and 537–561°C in air atmosphere. All polyimides were amorphous according to X‐ray determination. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1425–1433, 1999     

Synthesis of head‐to‐tail polyurethanes from nonsymmetric diisocyanate and ethylene glycol with organotin catalysts

An ordered head‐to‐tail (HT) polyurethane was successfully prepared by the polyaddition reaction of p‐isocyanatobenzyl isocyanate with ethylene glycol with dibutyltin dilaurate as a catalyst. Furthermore, the HT regularity of polyurethane was improved to 83% with 1,1,3,3‐tetraphenyl‐1,3‐dichlorodistannoxane. The polymerization was conducted in N,N‐dimethylformamide at 30 °C with both monomers mixed at once. The microstructure of the polymer was investigated by ¹H and ¹³C NMR spectroscopy, and the polymer obtained by the polyaddition reaction had the expected HT linkages. The constitutional regularity of the polymers influenced the thermal properties and crystallinity. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 416–429, 2001     

Synthesis and characterization of novel polyamide‐imides containing noncoplanar 2,2′‐dimethyl‐4,4′‐biphenylene unit

A new diimide‐dicarboxylic acid, 2,2′‐dimethyl‐4,4′‐bis(4‐trimellitimidophenoxy)biphenyl (DBTPB), containing a noncoplanar 2,2′‐dimethyl‐4,4′‐biphenylene unit was synthesized by the condensation reaction of 2,2′‐dimethyl‐4,4′‐bis(4‐minophenoxy)biphenyl (DBAPB) with trimellitic anhydride in glacial acetic acid. A series of new polyamide‐imides were prepared by direct polycondensation of DBAPB and various aromatic diamines in N‐methyl‐2‐pyrrolidinone (NMP), using triphenyl phosphite and pyridine as condensing agents. The polymers were produced with high yield and moderate to high inherent viscosities of 0.86–1.33 dL · g⁻¹. Wide‐angle X‐ray diffractograms revealed that the polymers were amorphous. Most of the polymers exhibited good solubility and could be readily dissolved in various solvents such as NMP, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), dimethyl sulfoxide, pyridine, cyclohexanone, and tetrahydrofuran. These polyamide‐imides had glass‐transition temperatures between 224–302 °C and 10% weight loss temperatures in the range of 501–563 °C in nitrogen atmosphere. The tough polymer films, obtained by casting from DMAc solution, had a tensile strength range of 93–115 MPa and a tensile modulus range of 2.0–2.3 GPa. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 63–70, 2001     

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

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

Synthesis and characterization of novel poly(amide‐imide)s containing 1,3‐diamino mesitylene moieties

A series of poly(amide‐imide)s were prepared using a new monomer, 1,3‐bis(trimellitimido)‐2,4,6‐trimethyl benzene (BTB), with four different diamines: 1,4‐phenylene diamine (PDA), 2,4‐diamino mesitylene (DAM), 2,2′‐dimethyl‐4,4′‐diamino biphenyl (DMDB), and 2,2′‐bis(trifluoromethyl)‐4,4′‐diamino biphenyl (TFDB). They were prepared by the condensation method in N‐methyl‐2‐pyrrolidinone (NMP) solvent using triphenyl phosphate and pyridine as condensing agents. The synthesized poly(amide‐imide)s were characterized by Fourier transform infrared and ¹H NMR techniques. Films were prepared and characterized using DSC, thermogravimetric analysis (TGA), a prism coupler, and a film dielectric property analyzer. DSC measurement showed that the glass‐transition temperatures of the polymers were in the range of 259–327 °C. TGA analysis showed 5% weight loss, in the range of 472–514 °C. The refractive index varied from 1.6004 to 1.6586 in the following increasing order: BTB‐TFBM < BTB‐DAM < BTB‐DMDB < BTB‐PDA. For the poly(amide‐imide) films, the birefringence varied in the range of 0.0319–0.0580, in the following increasing order: BTB‐DAM < BTB‐TFBM < BTB‐DMDB < BTB‐PDA. The capacitance method showed that the dielectric constant of poly(amide‐imide) varied with the diamine structure; no difference was found by the optical method. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 137–143, 2004     

Diethylbis(2,2′‐bipyridine)iron/MAO. A Very Active and Stereospecific Catalyst for 1,3‐Diene Polymerization

Diethylbis(2,2′‐bipyridine)Fe/MAO is an extremely active catalyst for the polymerization of 1,3‐dienes. Polymers with a 1,2 or 3,4 structure are formed from butadiene, isoprene, (E)‐1,3‐pentadiene and 3‐methyl‐1,3‐pentadiene, while cis‐1,4 polymers are derived from 2,3‐dimethyl‐1,3‐butadiene. The 1,2 (3,4) polymers obtained at 25°C are amorphous, while those obtained below 0°C are crystalline, as was determined by means of X‐ray diffraction. Mechanistic implications of the results are briefly discussed.     

9,9′‐spirobifluorene‐containing polycarbonates: Transparent polymers with high refractive index and low birefringence

Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl₃, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010     

Synthesis of statistical glycidyl methacrylate‐n‐vinyl pyrrolidone copolymers and their reaction with naproxen

Free‐radical copolymerization of glycidyl methacrylate (GMA) with N‐vinylpyrrolidone (VPD) was carried out at 50 °C using 3.0 mol · L^?1 of N,N′‐dimethylformamide solution and 9.0 · 10^?3 mol · L^?1 of 2,2′‐azobisisobutyronitrile as an initiator. The modification reaction of GMA‐VPD copolymers with a model bioactive carboxylic acid, 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen), was studied in the homogeneous phase using basic catalysts. The influence of the type of catalyst and the GMA content was evaluated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1192–1199, 2002     

Synthesis of well‐defined three‐armed polystyrene having thiourethane–isocyanurate as the core structure derived from trifunctional five‐membered cyclic dithiocarbonate

The synthesis of a three‐armed polymer with an isocyanurate–thiourethane core structure is described. Monofunctional reversible addition–fragmentation chain transfer (RAFT) agent 2 and trifunctional RAFT agent 5 were prepared from mercapto‐thiourethane and tris(mercapto‐thiourethane), which were obtained from the aminolysis of mono‐ and trifunctional five‐membered cyclic dithiocarbonates, respectively. The radical polymerization of styrene in the presence of 2,2′‐azobis(isobutyronitrile) and RAFT agent 2 in bulk at 60 °C proceeded in a controlled fashion to afford the corresponding polystyrene with desired molecular weights (number‐average molecular weight = 3000–10,100) and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight < 1.13). On the basis of the successful results with the monofunctional RAFT agents, three‐armed polystyrene with thiourethane–isocyanurate as the core structure could be obtained with trifunctional RAFT agent 5 in a similar manner. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5498–5505, 2005     

From metal‐catalyzed radical telomerization to metal‐catalyzed radical polymerization of vinyl chloride: Toward living radical polymerization of vinyl chloride

The metal‐catalyzed radical polymerization of vinyl chloride (VC) in ortho‐dichlorobenzene initiated with various activated halides, such as α,α‐dihaloalkanes, α,α,α‐trihaloalkanes, perfloroalkyl halides, benzyl halides, pseudohalides, allyl halides, sulfonyl halides, α‐haloesters, α‐halonitriles, and imidyl halides, in the presence of Cu(0)/2,2′‐bipyridine, Fe(0)/o‐phenantroline, TiCp₂Cl₂, and other metal catalysts is reported. The formation of the monoadduct between the initiator and VC was achieved with all catalysts. However, propagation was observed only for metals in their zero oxidation state because they were able to reinitiate from geminal dihalo or allylic chloride structures. Poly(vinyl chloride) with molecular weights larger then the theoretical limit allowed by chain transfer to VC were obtained even at 130 °C. In addition, the most elemental features of a living radical polymerization, such as a linear dependence of the molecular weight and a decrease of polydispersity with conversion, were observed for the most promising systems based on iodine‐containing initiators and Cu(0), that is, I? CH₂? Ph? CH₂? I/Cu(0)/bpy (where bpy = 2,2′‐bipyridyl), at 130 °C. However, because of the formation of inactive species via chain transfer to VC and other side reactions, the observed conversions were in most cases lower than 40%. A mechanistic interpretation of the chain transfer to monomer in the presence of Cu species is proposed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3392–3418, 2001     

Free‐radical crosslinking copolymerization of 2,2′‐azobis[N‐(2‐propenyl)‐2‐methylpropionamide] with vinyl benzoate resulting in polymeric azo initiators

2,2′‐Azobis[N‐(2‐propenyl)‐2‐methylpropionamide] (APMPA) with two carbon–carbon double bonds and an azo group was copolymerized with vinyl benzoate (VBz) at 60 °C, resulting in azo groups containing VBz/APMPA prepolymers and crosslinked polymers as soluble and insoluble polymeric azo initiators, respectively. The polymerization characteristics of APMPA as a novel diallyl monomer were clarified with the rate and degree of polymerization and the monomer reactivity ratios. The gelation behaviors in VBz/APMPA crosslinking copolymerizations were examined in detail with a comparison of the actual gel point and the theoretical gel point calculated according to Stockmayer's equation with the tentative assumption of equal reactivity for both vinyl groups belonging to VBz and APMPA. The effectiveness of the resulting branched or crosslinked poly(VBz‐co‐APMPA)s as soluble or insoluble polymeric azo initiators, respectively, at providing graft polymers through the cleavage of azo groups at an elevated temperature was examined by the polymerization of allyl benzoate at 120 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 317–325, 2002     

Synthesis and characterization of aromatic cyclolinear phosphazene polyetherketones containing bis‐Spiro‐substituted cyclotriphosphazene unit

A novel monomer, 2,2‐bis‐(4′‐fluorobenzoylphenoxy)‐4,4,6,6‐bis[spiro‐(2′,2″‐dioxy‐1′, 1′‐biphenylyl)] cyclotriphosphazene, was synthesized and polymerized with 4,4′‐difluorobenzophenone as a comonomer and 4,4′‐isopropylidenediphenol or 4,4′‐(hexafluoroisopropylidene) diphenol in N,N‐dimethylacetamide at 162 °C for 4 h to give two series of aromatic cyclolinear phosphazene polyetherketones containing bis‐spiro‐substituted cyclotriphosphazene groups. The structure of the monomer was confirmed by ¹H, ¹³C, and ³¹P NMR. The effect of the incorporation of the bis‐spiro‐substituted cyclotriphosphazene group on the thermal properties of these polymers was investigated by DSC and thermogravimetric analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2993–2997, 2001     

New organo‐soluble aromatic polyimides based on 3,3′,5,5′‐tetrabromo‐2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]propane dianhydride and aromatic diamines

New aromatic tetracarboxylic dianhydride, having isopropylidene and bromo‐substituted arylene ether structure 3,3′,5,5′‐tetrabromo‐2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]propane dianhydride, was synthesized by the reaction of 4‐nitrophthalonitrile with 3,3′,5,5′‐tetrabromobisphenol A, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). The novel aromatic polyetherimides having inherent viscosities up to 1.04 dL g⁻¹ were obtained by either a one‐step or a conventional two‐step polymerization process starting from the bis(ether anhydride) and various aromatic diamines. All the polyimides showed typical amorphous diffraction patterns. Most of the polyimides were readily soluble in common organic solvents such as N,N‐dimethylacetamide (DMAc), N‐methyl‐2‐pyrrolidone (NMP), pyridine, and even in less polar solvents like chloroform and tetrahydrofuran (THF). These aromatic polyimides had glass transition temperatures in the range of 256–303°C, depending on the nature of the diamine moiety. Thermogravimetric analysis (TGA) showed that all polymers were stable, with 10% weight loss recorded above 470°C in nitrogen. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1673–1680, 1999