Synthesis and characterization of novel soluble pyridine‐containing polyimides based on 4‐phenyl‐2,6‐bis[4‐(4‐aminophenoxy)phenyl]‐pyridine and various aromatic dianhydrides

A new kind of pyridine‐containing aromatic diamine monomer, 4‐phenyl‐2,6‐bis[4‐(4‐aminophenoxy)phenyl]‐pyridine (PAPP), was successfully synthesized by a modified chichibabin reaction of benzaldehyde and a substituted acetophenone, 4‐(4‐nitrophenoxy)‐acetophenone (NPAP), followed by a reduction of the resulting dinitro compound 4‐phenyl‐2,6‐bis[4‐(4‐nitrophenoxy)phenyl]‐pyridine (PNPP) with Pd/C and hydrazine monohydrate. The aromatic diamine was employed to synthesize a series of new pyridine‐containing polyimides by polycondensation with various aromatic dianhydrides in N‐methy‐2‐pyrrolidone (NMP) via the conventional two‐step method, i.e., ring‐opening polycondensation forming the poly (amic acid)s and further thermal or chemical imidization forming polyimides. The inherent viscosities of the resulting polyimides were in the range of 0.79–1.13 dL/g, and most of them were soluble in common organic solvents such as N,N‐dimethylacetamide (DMAc), NMP, and tetrahydrofuran (THF), etc. Meanwhile, strong and flexible polyimide films were obtained, which had good thermal stability, with the glass transition temperatures (T_g) of 268–338°C and the temperature at 5% weight loss of 521–548°C in air atmosphere, as well as outstanding mechanical properties with tensile strengths of 89.2–112.1 MPa and elongations at break of 9.5–15.4%. The polyimides also were found to possess low dielectric constants ranging from 2.53 to 3.11. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 212–219, 2007     

Synthesis,characterization, and properties of novel aromatic polyamides containing phthalazinone moiety

A unsymmetrical and kink non-coplanar heterocyclic dicarboxylic acid monomer, 4-[4-(4-carboxy phenoxy)-naphthyl]-2-(4-carboxyphenyl)phthalazin-1-one (3) was successfully synthesized with high purity and high yields. A series of novel polyamides containing phthalazinone were prepared from the newly synthesized dicarboxylic acid with various aromatic diamines by means of the phosphorylation polycondensation reaction. Molecular weights of the obtained polyamides were evaluated viscometrically, and the inherent viscosities (η_inh) measured were in the range 0.54–0.69 dL/g. These polyamides were amorphous and readily soluble in many organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimetheylformamide, dimethyl sulfoxide, pyridine, and m-cresol etc., and they could easily be solution-cast into transparent, flexible films with good mechanical properties, with tensile strength ranging from 63.9 to 81.6 MPa and elongation at break from 7.2 to 11.4%. These polymers still kept good thermal stability with high-glass transition temperatures in the range of 283–338 °C, and the decomposition temperature in nitrogen for a 10% weight-loss temperatures in excess of 490 °C, and char yield at 800 °C in nitrogen ranged from 56 to 63%. Furthermore, the polyamides films were essentially colorless; their cut-off wavelengths were between 365 and 379 nm.     

Synthesis and characterization of new soluble polyamides from an unsymmetrical diamine bearing a bulky triaryl pyridine pendent group

New unsymmetrical diamine monomer containing triaryl pyridine pendent group, 2,4‐diaminophenyl [4‐(2, 6‐diphenyl‐4‐pyridyl) phenyl]ether, was synthesized via aromatic substitution reaction of 1‐chloro‐2,4‐dinitrobenzene with 4‐(2,6‐diphenyl‐4‐pyridyl) phenol, followed by Pd/C‐catalyzed hydrazine reduction. Five Polyamides (PA) were prepared by the phosphorylation polycondensation of different dicarboxylic diacids with the diamine. Inherent viscosities of PAs were in the range 0.51–0.59 g/dL indicating formation of medium molecular weight polymers. The weight and number average molecular weights of a PA, (PA‐d), determined by GPC were 6944 g/mol and 17,369 g/mol, respectively. PAs exhibited glass‐transition temperatures (T_g) in the range 140–235°C. These polymers, essentially amorphous, were soluble in polar aprotic solvents such as DMF, NMP, DMAc, DMSO, pyridine, m‐cresol, and THF. The initial decomposition temperatures (T_i) of PAs, determined by TGA in air, were in the range 300–380°C indicating their good thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of organosoluble poly(arylate‐imide)s prepared from direct polycondensation of bis(trimellitimide)‐diacids and various bisphenols

Three diimide‐diacids, 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]hexafluoropropane ( I‐A ), 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]propane ( I‐B ), and 5,5′‐bis[4‐ (4‐trimellitimidophenoxy)phenyl]hexahydro‐4,7‐methanoindan ( I‐C ), were prepared by the azeotropic condensation of trimellitic anhydride with three analogous diamines. Three series of alternating aromatic poly(arylate‐imide)s, having inherent viscosities of 0.41–0.82 dL/g, were synthesized from these diimide‐diacids ( I‐A , I‐B , and I‐C ) with various bisphenols by direct polycondensation using diphenyl chlorophosphate and pyridine as condensing agents. All of the polymers were readily soluble in a variety of organic solvents such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, and even in the less polar tetrahydrofuran. These polymers could be cast into transparent and tough films, which had strength at break values ranging from 73 to 98 MPa, elongation at break from 6 to 11%, and initial modulus from 1.6 to 2.2 GPa. The softening temperatures of the polymers were recorded at 145–248°C. They had 10% weight loss at a temperature above 450°C and left 35–51% residue even at 800°C in nitrogen. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3818–3825, 2003     

Synthesis and properties of novel aromatic polyamides with xanthene cardo groups

Two novel monomers, 9,9‐bis[4‐(4‐carboxyphenoxy)phenyl]xanthene (BCAPX) and 9,9‐bis[4‐(4‐aminophenoxy)phenyl]xanthene (BAPX) were prepared in two main steps starting from nucleophilic substitution of 9,9‐bis(4‐hydroxyphenyl)xanthene (BHPX) with p‐fluorobenzonitrile and p‐chloronitrobenzene, respectively. Using triphenyl phosphite and pyridine as condensing agents, two series of polyamides containing xanthene cardo groups with the inherent viscosities (0.82–1.32 dL/g) were prepared by polycondensation from BCAPX with various aromatic diamines or from BAPX with various aromatic dicarboxylic acids in an N‐methyl‐2‐pyrrolidone (NMP) solution containing dissolved calcium chloride, respectively. All new polyamides were amorphous and readily soluble in various polar solvents such as N,N‐dimethylformamide (DMF), NMP, N,N‐dimethylacetamide (DMAc) and pyridine. These polymers showed relatively high glass transition temperatures between 264 and 308°C, decomposition temperatures at 10% weight loss ranging from 502 to 540°C and 488 to 515°C in nitrogen and air, respectively, and char yields at 800°C in nitrogen higher than 56%. Transparent, flexible, and tough films of these polymers cast from DMAc solutions exhibited tensile strengths ranging from 86 to 109 MPa, elongations at break from 13 to 22%, and initial moduli from 2.15 to 2.63 GPa. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of novel polyamides containing sulfone‐ether linkages and xanthene cardo groups

In order to obtain polyamides with enhanced solubility and processability, as well as good mechanical and thermal properties, several novel polyamides containing sulfone‐ether linkages and xanthene cardo groups based on a new diamine monomer, 9,9‐bis[4‐(4‐aminophenoxy)phenyl]xanthene (BAPX), were investigated. The BAPX monomer was synthesized via a two‐step process consisting of an aromatic nucleophilic substitution reaction of readily available 4‐chloronitrobenzene with 9,9‐bis(4‐hydroxyphenyl)xanthene in the presence of potassium carbonate in N,N‐dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. Four novel aromatic polyamides containing sulfone‐ether linkages and xanthene cardo groups with inherent viscosities between 0.98 and 1.22 dL g^?1 were prepared by low‐temperature polycondensation of BAPX with 4,4′‐sulfonyldibenzoyl chloride, 4,4′‐[sulfonyl‐bis(4‐phenyleneoxy)]dibenzoyl chloride, 3,3′‐[sulfonyl‐bis(4‐phenyleneoxy)]dibenzoyl chloride and 4,4′‐[sulfonyl‐bis(2,6‐dimethyl‐1,4‐phenyleneoxy)]dibenzoyl chloride in N,N‐dimethylacetamide (DMAc) solution containing pyridine. All these new polyamides were amorphous and readily soluble in various polar solvents such as DMAc and N‐methylpyrrolidone. These polymers showed relatively high glass transition temperatures in the range 238–298 °C, almost no weight loss up to 450 °C in air or nitrogen atmosphere, decomposition temperatures at 10% weight loss ranging from 472 to 523 °C and 465 to 512 °C in nitrogen and air, respectively, and char yields at 800 °C in nitrogen higher than 50 wt%. Transparent, flexible and tough films of these polymers cast from DMAc solution exhibited tensile strengths ranging from 78 to 87 MPa, elongations at break from 9 to 13% and initial moduli from 1.7 to 2.2 GPa. Primary characterization of these novel polyamides shows that they might serve as new candidates for processable high‐performance polymeric materials. Copyright © 2010 Society of Chemical Industry     

Synthesis and characterization of new aromatic poly(amide–imide)s based on 4‐aryl‐2,6‐bis(4‐trimellitimidophenyl) pyridines

New diimide–dicarboxylic acids, ie 4‐phenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine and 4‐p‐biphenyl‐2,6‐bis‐(4‐trimellitimidophenyl)pyridine, were synthesized by the condensation reaction of 4‐phenyl‐2,6‐bis(4‐aminophenyl)pyridine and 4‐p‐biphenyl‐2,6‐bis(4‐aminophenyl)pyridine with trimellitic anhydride in glacial acetic acid or dimethylformamide. The monomers were fully characterized by FT‐IR and NMR spectroscopies, and elemental analyses. A series of novel poly(amide–imide)s with inherent viscosities of 0.68–0.87 dl g^?1 was prepared from the two diimide–diacids with various aromatic diamines by direct polycondensation. The poly(amide–imide)s were characterized by FT‐IR and NMR spectroscopies. The λ_max data for the resulting poly(amide–imide)s were in the range of 260–292 nm. These polymers exhibited good solubilities in polar aprotic solvents. The 10 % weight loss temperatures are above 485 °C under a nitrogen atmosphere. Copyright © 2004 Society of Chemical Industry     

Synthesis and properties of fluorinated polyamideimides with high solubility

A series of fluorinated polyamideimides (PAIs) were synthesized by the direct polycondensation of a novel diimide‐diacid, 1,4‐bis(trimellitimido‐2‐trifluoromethylphenoxy) benzene (BTTFB), with aromatic diamines by using triphenyl phosphite (TPP) and pyridine as condensation agents in a medium consisting of N‐methyl‐2‐pyrrolidone (NMP) and CaCl₂. Most of the resulting polymers showed an amorphous nature. All the fluorinated PAIs were readily soluble in a variety of organic solvents such as NMP, N,N‐dimethyl acetamide, dimethylformamide, and dimethyl sulfoxide and could even be dissolved in less polar solvents such as THF and m‐cresol. The PAIs had inherent viscosities of 0.77–0.93 dL/g, depending on the diamines. All the soluble PAIs afforded transparent, flexible, and tough films that exhibited excellent thermal stability, good mechanical properties, and low moisture absorption. The glass transition temperatures of these PAIs ranged from 244 to 272°C and the 5% weight loss temperatures were >525°C in nitrogen. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 321–327, 2005     

Synthesis and study of new poly(ester‐imide)s containing triptycene groups

A new triptycene‐containing dicarboxylic acid monomer was successfully synthesized by refluxing the diamine, bis(4‐aminophenoxy)phenyl triptycene with trimellitic anhydride in glacial acetic anhydride. A series of novel thermally stable poly(ester‐imide)s were prepared from dicarboxylic acid, bis(4‐trimellitimido phenoxy)phenyl triptycene with various diols by the direct polycondensation. The polymers were obtained in quantitative yields with inherent viscosities of 0.27–0.74 dL g^?1. The resulting polymers dissolved in N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, and pyridine. These polymers were fairly stable up to a temperature >450°C and lost 10% weight in the range of 477°C and 575°C in nitrogen. The UV–V is absorption spectra revealed that most of the polymers had absorption maxima around 310 and 341 nm. POLYM. ENG. SCI., 54:2252–2257, 2014. © 2013 Society of Plastics Engineers     

Synthesis and lyotropic behavior of mesogen‐linked cellulose acetates

Three aromatic (p‐carboxyl phenyl) esters, 4‐(benzoyloxy) benzoic acid, 4‐(4′‐methylbenzoyloxy) benzoic acid, and 4‐(4′‐chlorobenzoyloxy) benzoic acid, were synthesized and they showed nematic monotropic or thermotropic behavior. The mesogen‐linked cellulose acetates were first prepared by the reaction of aromatic (p‐carboxyl phenyl) esters with cellulose acetate through esterification in the presence of N,N‐dicyclohexylcarbodiimide (DCC) and 4‐dimethylaminopyridine (DMAP). Their degrees of mesogenic unit substitution (DS_‐meso) were between 0.27 and 0.41. It was found that they can form cholesteric lyotropic phases in dichloroacetic acid and their critical concentration was about 25 wt %. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2693–2697, 2004     

Synthesis and characterisation of organosoluble polyimides containing the anisyl moiety

A new type of diamine monomer containing the anisyl moiety was synthesized via a straight‐forward one‐step procedure. Anisaldehyde was reacted with 2,6‐dimethylaniline in the presence of dry HCl to attain bis(4‐amino‐3,5‐dimethylphenyl)anisylmethane. A series of organo‐soluble polyimides were prepared using the anisyl diamine and various aromatic dianhydrides via a two step method involving thermal imidization. All polyimides are soluble in strong polar solvents such as N‐methyl‐2‐pyrollidone, N,N‐Dimethylformamide, and N,N‐DimethylAcetamide. The polyimides show excellent thermal stability and good mechanical properties. The glass transition temperatures of the polyimides are in the range 265–294 °C. The tensile strengths are in the range 79–99 MPa and the temperatures at which 10 % weight loss occurs are in the range 460–496 °C. Copyright © 2004 Society of Chemical Industry     

High glass transitions and fluorescence of novel organosoluble poly(arylene ether)s containing kink noncoplanar heterocyclic structures

A novel unsymmetrical and kink noncoplanar heterocyclic bisphenol-like monomer, 4-(4-hydroxynaphthalenyl)phthalazin-1-one (2), was synthesized in a two-step reaction starting from 1-naphthol and phthalic anhydride via Friedel-Crafts acylation reaction and cyclization with hydrazine hydrate. Two heterocyclic poly(arylene ether)s were prepared conveniently from monomer 2 and two activated dihalide monomers by a N-C coupling reaction. The polycondensation proceeded quantitatively in N,N-dimethylacetamide in the presence of anhydrous potassium carbonate and afford the polymers with inherent viscosities of 0.46 and 0.34 dL/g. Thermal analysis showed that the polymers had excellent thermal properties. The glass transition temperatures were 277 °C and 316 °C respectively, and the temperatures of 5% weight loss were all above 500 °C in nitrogen atmosphere. The unsymmetrical and kink noncoplanar structures of the polymers chains could disturb interchain and intrachain interactions and make them amorphous and readily soluble in polar, aprotic solvents. The dilute solution of the polymers in chloroform showed strong optical absorption in ultraviolet region, and exhibited violet-blue fluorescence with emission maxima at 400-470 nm.     

Soluble polyimides based on a novel pyridine-containing diamine <Emphasis Type="Italic">m</Emphasis>,<Emphasis Type="Italic">p</Emphasis>-PAPP and various aromatic dianhydrides

A novel pyridine-containing aromatic diamine monomer, 4-phenyl-2,6-bis[3-(4-aminophenoxy)phenyl]pyridine (m,p-PAPP), was successfully synthesized by a modified Chichibabin reaction of benzaldehyde and a substituted acetophenone, 3-(4-nitrophenoxy)acetophenone (m,p-NPAP), followed by a reduction of the resulting dinitro compound 4-phenyl-2,6-bis[3-(4-nitrophenoxy)phenyl]pyridine (m,p-PNPP) with Pd/C and hydrazine monohydrate. The aromatic diamine was employed to synthesize a series of pyridine-containing polyimides (PIs) by polycondensation with various aromatic dianhydrides in N,N-dimethylformamide (DMF) via the conventional two-step method, and further thermal or chemical imidization forming PIs. The inherent viscosities of the resulting poly(amic acid)s and PIs were 0.59–0.73 and 0.56–0.68 dL/g; most of the PIs obtained by chemical imidization were readily soluble in common organic solvents such as DMF, N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), etc. Meanwhile, strong and flexible PI films were obtained, which had good thermal stability, with the glass transition temperature (T _g) of 204.5–237.4 °C and the temperature at 10% weight loss of 527.7–552.0 °C in nitrogen atmosphere, as well as outstanding mechanical properties with tensile strengths of 88.6–90.4 MPa, a tensile moduli of 1.04–1.56 GPa, and elongations at break of 7.2–8.7%. The PI films also were found to possess low water uptake of 0.89–0.98%.     

Synthesis and characterization of novel aromatic polyamides bearing CF3, quinoxaline‐anthraquinone pendants: Study of photophysical and electrochemical properties by using nanocomposite electrode paste

A new aromatic diamine, 2,3‐bis(4‐(4‐amino‐2‐(trifluoromethyl) phenoxy)phenyl)naphtho[2,3‐f]quinoxaline‐7,12‐dione, was synthesized and fully characterized by using FTIR, ¹H and ¹³C NMR, DEPT technique, and elemental analysis. A series of novel fluorescent anthraquinone‐quinoxaline containing polyamides (PAs) with inherent viscosities of 0.39–0.62 dL/g was prepared by direct polycondensation of the diamine with various dicarboxylic acids. These PAs were readily soluble in many polar aprotic organic solvents and could be solution‐cast into tough and flexible films. The PAs exhibited glass transition temperatures (T_g)s between 230 and 323°C, and 10% weight loss temperatures in the range of 362–433°C in N₂. All of the PAs have fluorescence emission in solution and in solid state with maxima around 452–510 nm and with the quantum yields in the range of 6–17%. Also, cyclic voltammetry (CV) method was used to study the electrochemical oxidation behavior of these polymers at the surface of a modified multiwalled carbon nanotube (MWCNT)s glassy electrode. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Tautomerism,crystal structure,and copper(II) complexation of isomeric pyridonylazo dyes derived from 2‐ and 4‐aminobenzoic acids

A pair of isomeric aromatic heterocyclic dyes, bearing the same N‐methyl pyridine‐2,6‐dione coupling component but a different 2‐ or 4‐aminobenzoic acid diazo component, were characterised structurally and spectroscopically. X‐ray single‐crystal diffraction analyses revealed that they both adopt the same hydrazone‐tautomeric form and planar molecular conformation between the pyridine and phenyl rings. Furthermore, azo–hydrazone transformation was achieved for the 2‐aminobenzoic‐acid‐based dye after Cu(II) ion complexation, as verified by the formation of a neutral Cu(II) dye–metal complex. The coordination geometry of the central Cu(II) ion exhibits a slightly distorted pyramid with a value of 0.028, where the ligand loses a proton during complexation and serves as the tridentate coordination mode. In addition, thermogravimetric analysis and corresponding differential thermal analysis for the isomeric pair showed that they both have excellent thermal stability, and 4‐aminobenzoic‐acid‐based dye has a higher decomposition temperature (319 °C) than the 2‐aminobenzoic‐acid‐based dye (312 °C). To the best of our knowledge, this is the first structural study on aromatic heterocyclic dyes having aminobenzoic acid and pyridine‐2,6‐dione components at the same time.     

Synthesis and properties of polyamides based on 5,5′‐bis[4‐(4‐aminophenoxy)phenyl]‐hexahydro‐4,7‐methanoindan

A new diamine 5,5′‐bis[4‐(4‐aminophenoxy)phenyl]‐hexahydro‐4,7‐methanoindan ( 3 ) was prepared through the nucleophilic displacement of 5,5′‐bis(4‐hydroxylphenyl)‐hexahydro‐4,7‐methanoindan ( 1 ) with p‐halonitrobenzene in the presence of K₂CO₃ in N,N‐dimethylformamide (DMF), followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new polyamides were synthesized by the direct polycondensation of diamine 3 with various aromatic dicarboxylic acids. The polymers were obtained in quantitative yields with inherent viscosities of 0.76–1.02 dl g⁻¹. All the polymers were soluble in aprotic dipolar solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidone (NMP), and could be solution cast into transparent, flexible and tough films. The glass transition temperatures of the polyamides were in the range 245–282 °C; their 10% weight loss temperatures were above 468 °C in nitrogen and above 465 °C in air. © 2000 Society of Chemical Industry     

Synthesis of aromatic poly(urea‐imide) with heterocyclic side‐chain structure

The poly(urea‐imide) copolymers with inherent viscosity of 0.81–1.08 dL/g were synthesized by reacting aryl ether diamine or its polyurea prepolymer with various diisocyanate‐terminated polyimide prepolymers. The aryl ether diamine was obtained by first nucleophilic substitution of phenolphthalein with p‐chloronitrobenzene in the presence of anhydrous potassium carbonate to form a dinitro aryl ether, and then further hydrogenated to diamine. The polyimide prepolymers were prepared by using 4,4′‐diphenylmethane diisocyanate to react with pyromellitic dianhydride, 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride, or 3,3′,4,4′‐sulfonyldiphthalic anhydride by using the direct one‐pot method to improve their solubility, but without sacrificing thermal property. These copolymers are amorphous and readily soluble in a wide range of organic solvents such as N‐methyl‐2‐pyrrolidone, dimethylimidazole, N,N‐dimethylacetamide, dimethyl sulfoxide, N,N‐dimethylformamide, m‐cresol, and sulfolane. All the poly(urea‐imides) have glass transition temperatures in the range of 205–240°C and show a 10 wt % loss at 326–352°C in nitrogen and 324–350°C in air. The tensile strength, elongation at break, and initial modulus of these copolymer films range from 42 to 79 MPa, 5 to 16%, and 1.23 to 2.02 GPa, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1719–1730, 1999     

Organosoluble and light‐colored fluorinated polyimides based on 2,2‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy)phenyl]propane and aromatic dianhydrides

A novel fluorinated diamine monomer, 2,2‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy)phenyl]propane (2), was prepared through the nucleophilic substitution reaction of 2‐chloro‐5‐nitrobenzotrifluoride with 2,2‐bis(4‐hydroxyphenyl)propane in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Polyimides were synthesized from diamine 2 and various aromatic dianhydrides 3a–f via thermal imidization. These polymers had inherent viscosities ranging from 0.73 to 1.29 dL/g. Polyimides 5a–f were soluble in amide polar solvents and even in less polar solvents. These films had tensile strengths of 87–100 MPa, elongations to break of 8–29%, and initial moduli of 1.7–2.2 GPa. The glass transition temperatures (T_g) of 5a–f were in the range of 222–271°C, and the 10% weight loss temperatures (T₁₀) of them were all above 493°C. Compared with polyimides 6 series based on 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane (BAPP) and polyimides 7 based on 2,2‐Bis[4‐(4‐aminophenoxy)phenyl]hexafluoropropane (6FBAPP), the 5 series showed better solubility and lower color intensity, dielectric constant, and lower moisture absorption. Their films had cutoff wavelengths between 363 and 404 nm, b* values ranging from 8 to 62, dielectric constants of 2.68–3.16 (1 MHz), and moisture absorptions in the range of 0.04–0.35 wt %. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 922–935, 2005     

Preparation and properties of soluble aromatic polyetherimides based on 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride

Aromatic polyetherimides were synthesized from a fluorine containing aromatic carboxylic acid dianhydride, 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride (6F‐BABPA) and five typical aromatic diamines including 1,1‐bis(4‐aminophenyl)‐1‐phenyl‐2,2,2‐trifluoroethane (3F‐DAM) by two‐step procedures—amidation to polyamic acids (PAA), followed by thermal imidization of PAA. The chemical and physical properties of the newly prepared polyetherimides (PEI) were compared in terms of their chemical structures, inherent viscosities, mechanical, and thermal properties. All polyetherimides were well soluble in common organic solvents such as N‐methyl‐2‐pyrolidone (NMP), N,N‐dimethylformamide (DMF), N,N‐dimethylacetamide (DMAc), pyridine, and methylene chloride. A PEI prepared from 6F‐BABPA/3F‐DAM was especially easily dissolved in NMP. The glass transition temperature (T_g) range of the obtained PEI was 209–257°C. The dielectric constants and refractive index were 2.8–3.2 and 1.61–1.56, respectively. The polyetherimide, 6F‐BABPA/BAPP, with a low fluorine content (11.4% fluorine content), has 0.99% water absorption, whereas the polyetherimide, 6F‐BABPA/4‐BDAP, having a high fluorine content (26.0% fluorine content) showed 0.35% of water absorption. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 249–257, 2000     

Synthesis and characterization of Schiff‐base‐containing polyimides

Benzyl bisthiosemicarbazone and its complexes with nickel (NiLH₄) and copper (CuLH₄) were used as diamine monomers for the synthesis of new Schiff‐base polyimides. The solution polycondensation of these monomers with the aromatic dianhydrides afforded metal‐containing Schiff‐base polyimides with inherent viscosities of 0.98–1.33 dL/g (measured in N‐methyl‐2‐pyrrolidone at 25°C). The polyimides were generally soluble in a wide range of solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, tetrachloroethane, hexamethylene phosphoramide, N‐methyl‐2‐pyrrolidone, ethyl acetate, and pyridine at room temperature. The initial degradation temperatures of the resultant polyimides fell in the range of 220–350°C in nitrogen with char yields ranging from 36 to 64% at 700°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010