Organosoluble and light-colored fluorinated polyimides based on 9,9-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]fluorene and aromatic dianhydrides

A novel fluorinated diamine monomer, 9,9-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]fluorene (II) was prepared via the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride with 9,9-bis(4-hydroxyphenyl)fluorene in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Polyimides V were synthesized from diamine II and various aromatic dianhydrides III _a-f via thermal imidization. These polymers had inherent viscosities ranging from 0.84 to 1.03 dL/g and were soluble in a variety of organic solvents such as NMP, DMAc, DMF, and DMSO, and some could even be dissolved in less polar solvents such as m-cresol, pyridine, and dioxane. Polyimide films V _a-f had tensile strengths of 85–105 MPa, elongations to break of 7–9%, and initial moduli of 2.13–2.42 GPa. The glass transition temperature of these polymers were in the range of 277–331 °C, their 10% weight loss temperatures were in the range of 539–594 °C in nitrogen and above 544 °C in air, and their char yields at 800 °C in nitrogen ranged between 55–65 wt%. Compared with nonfluorinated polyimides VI, V showed better solubility and lower color intensity. Low dielectric constants (2.68–2.85 at 1 MHz) and low moisture absorptions (0.12–0.24 wt%) were also observed. In particular, V _c-f afforded lightly-colored films, which had cutoff wavelengths lower than 385 nm and b* values ranging from 6 to 22.     

Synthesis and properties of poly(ether imide)s derived from 2,6-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride and aromatic diamines

A new naphthalene unit-containing bis(ether anhydride), 2,6-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride, was synthesized in three steps starting from the nucleophilic nitrodisplacement reaction of 2,6-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). High-molar-mass aromatic poly(ether imide)s were prepared using a conventional two-step polymerization process from the bis(ether anhydride) and various aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0.65–2.03 dL/g. The films of poly(ether imide)s derived from two rigid diamines, i.e. p-phenylenediamine and benzidine, crystallized during the thermal imidization process. The other poly(ether imide)s belonged to amorphous materials and could be fabricated into transparent, flexible, and tough films. These aromatic poly(ether imide) films had yield strengths of 104–131 MPa, tensile strengths of 102–153 MPa, elongation to break of 8–87%, and initial moduli of 1.6–3.2 GPa. The glass transition temperatures (T_g's) of poly(ether imide)s were recorded in the range of 220–277°C depending on the nature of the diamine moiety. All polymers were stable up to 500°C, with 10% weight loss being recorded above 550°C in both air and nitrogen atmospheres. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1657–1665, 1998     

Syntheses and properties of fluorinated polyamides and poly(amide imide)s based on 9,9-bis[4-(4-amino-2-trifluromethylphenoxy)phenyl]fluroene, aromatic dicarboxylic acids, and various monotrimellitimides and bistrimellitimides

A diamine, 9,9-bis[4-(4-amino-2-trifluromethylphenoxy)phenyl]fluroene (I) containing the CF₃ group, was prepared from 9,9-bis(4-hydroxyphenyl)fluorene and 2-chloro-5-nitrobenzotrifluoride. The imide-containing diacids (V _a-j and VI _a,b) were prepared by condensation reaction of amino acids, aromatic diamines, and trimellitic anhydride. Then, a series of soluble fluorinated polyamides (VII _a-e) and poly(amide imide)s (VIII _a-j and X _a,b) were synthesized from diamine (I) with various aromatic diacids II _a-h and the imide-containing diacids (V _a-j and VI _a,b) via direct polycondensation with triphenyl phosphate and pyridine. All polymers showed excellent solubility in amide-type solvents such as N-dimethylforamide and can also be dissolved in pyridine, m-cresol, and tetrahydrofuran. Polymers afford transparent and tough films by solvent casting. The glass transition temperature of these polymers were in the range of 278–366°C, and the poly(amide imide)s had better thermal stability than polyamides. In comparison with the isomeric IX _a-d, VIII _a-d showed a lighter color with lower b* (yellowness index) values than the corresponding IX series.     

Novel fluorinated poly(aryl ether)s derived from 1,2-bis(4-(4-fluorobenzoyl)phenoxy)-hexafluorocyclobutane

Two novel poly(aryl ether)s were prepared from 1,2-bis(4-(4-fluorobenzoyl)-phenoxy)-hexafluorocyclobutane and aromatic bisphenols by the aromatic nucleophilic substitution reaction in a polar aprotic solvent. These polymers have good thermal stability up to 341 °C with 10% weight loss in inert atmosphere and good solubility in common organic solvents such as THF, DMAc, DMF and DMSO.     

Synthesis and characterization of novel fluorinated polyimides derived from 1,3-bis(4-amino-2-trifluoromethylphenoxy)naphthalene and aromatic dianhydrides

A new structurally asymmetric diamine monomer containing flexible ether linkages and bulky trifluoromethyl substituents, namely 1,3-bis(4-amino-2-trifluoromethylphenoxy)naphthalene, was prepared from 1,3-dihydroxynaphthalene and 2-chloro-5-nitrobenzotrifluoride. New series of fluorinated polyimides were synthesized from the diamine with six commercially available aromatic tetracarboxylic dianhydrides using a conventional two-stage process with thermal or chemical imidization. The resulting polyimides were highly soluble in a variety of organic solvents and could afford transparent and tough films via solution casting. These polyimides exhibited moderately high glass-transition temperatures (by DSC) of 236-268 °C and softening temperatures (by thermomechanical analysis) of 231-250 °C, and they did not show significant decomposition before 500 °C under either nitrogen or air atmosphere. Also, they revealed low moisture absorptions (0.32-0.78%), low dielectric constants (2.81-3.24 at 10 kHz), and high optical transparency (ultraviolet-visible absorption cutoff wavelengths of 377-426 nm).     

Synthesis and optical properties of novel soluble and optically transparent semifluorinated poly (ether imide)s

A fluorinated diamine monomer containing flexible ether linkage and bulky trifluoromethyl substituents, namely, bis(4‐amino‐2‐trifluoromethylphenyl) ether (a), is employed to react with nonfluorinated 1,4‐bis(3,4‐dicarboxyphenoxy) benzene dianhydride (3) and CF₃‐free 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl] propane dianhydride (4), respectively, to prepare 2 novel soluble and optically transparent semi‐fluorinated poly (ether imide)s (PEIs; 3a and 4a). Compared with the corresponding PEIs based on nonfluorinated 4,4′‐diaminodiphenyl ether (b) and CF₃‐free pyromellitic dianhydride (5), the novel semifluorinated PEIs 3a and 4a not only display better solubility in some organic solvents and higher optical transparency with cutoff absorption wavelength (λ₀) below 370 nm but also maintain outstanding mechanical properties and thermal stability. 3a and 4a have tensile strength beyond 80 MPa and possess glass‐transition temperatures (T_g) beyond 210°C, coupled with the temperatures of 5% weight loss (T_5%) exceeding 500°C. It is also found that 3a and 4a exhibit contact angles against water beyond 110° and water absorptions below 0.8% together with dielectric constants less than 3.2.     

Synthesis and properties of new pyridine-bridged poly(ether-imide)s based on 4-(4-trifluoromethylphenyl)-2,6-bis[4-(4-aminophenoxy)phenyl]pyridine

A novel pyridine-containing aromatic diamine monomer, 4-(4-trifluoromethylphenyl)-2,6-bis[4-(4-aminophenoxy)phenyl]pyridine (FAPP), was synthesized via the modified Chichibabin pyridine synthesis of 4-(4-nitrophenoxy)-acetophenone with 4-trifluoromethyl-benzaldehyde, followed by a catalytic reduction. A series of fluorinated pyridine-bridged aromatic poly(ether-imide)s were prepared from the resulting diamine monomer with various aromatic dianhydrides via a conventional two-step process. The resulting polyimides exhibited good solubility in aprotic amide solvents and m-cresol, such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol, etc., which possessed the inherent viscosities of 0.76-0.91 dL/g. Strong and flexible poly(ether-imide) films were obtained, which showed excellent thermal properties with the glass transition temperatures of 268-353 °C, the temperature at 5% weight loss of 547-595 °C, and the residue at 700 °C of 65-74% in nitrogen, good mechanical properties with the tensile strengths of 87.6-104.2 MPa and elongations at breakage of 8.9-12.6%, and good optical transparency with the cut-off wavelengths of 357-380 nm, as well as low dielectric constants in the range of 2.49-3.04 at 1 MHz and low water uptake 0.43-0.69%. Furthermore, the resulted polyimides derived from FAPP were compared with non-fluorinated analogous polyimides and fluorinated analogous polyimides with trifluoromethyl groups in different positions, and the effects of substituents were also investigated and discussed.     

Synthesis and properties of poly(ether imide)s derived from 2,7-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride and various aromatic diamines

A naphthalene unit-containing bis(ether anhydride), 2,7-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride, was prepared in three steps starting from the nucleophilic nitrodisplacement reaction of 2,7-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). High-molar-mass aromatic poly(ether imide)s were synthesized using a conventional two-stage polymerization process from the bis(ether anhydride) and ten aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0.95–2.67 dL/g. The films of poly(ether imide)s derived from two rigid diamines, that is, p-phenylenediamine and benzidine, crystallized and embrittled during the thermal imidization process. The other poly(ether imide)s belonged to amorphous materials and could be fabricated into transparent, flexible, and tough films. These poly(ether imide) films had yield strengths of 91–115 MPa, tensile strengths of 89–136 MPa, elongation to break of 11–45%, and initial moduli of 1.7–2.2 GPa. The T_gs of poly(ether imide)s were recorded in the range of 222–256°C depending on the nature of the diamine moiety. All polymers were thermally stable up to 500°C, with 10% weight loss being recorded above 540°C in air and nitrogen atmospheres. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2281–2287, 1997     

New poly(amide–imide) syntheses. XXI. Synthesis and properties of aromatic poly(amide–imide)s based on 2,6-bis(4-trimellitimidophenoxy)naphthalene and aromatic diamines

A novel polymer-forming diimide–diacid, 2,6-bis(4-trimellitimidophenoxy)naphthalene, was prepared by the condensation reaction of 2,6-bis(4-aminophenoxy)naphthalene with trimellitic anhydride (TMA). A series of novel aromatic poly(amide–imide)s containing 2,6-bis(phenoxy)naphthalene units were prepared by the direct polycondensation of the diimide–diacid with various aromatic diamines using triphenyl phosphite (TPP) in N-methyl-2-pyrrolidone (NMP)/pyridine solution containing dissolved calcium chloride. Thirteen of the obtained polymers had inherent viscosities above 1.01 dL/g and up to 2.30 dL/g. Most of polymers were soluble in polar solvents such as DMAc and could be cast from their DMAc solutions into transparent, flexible, and tough films. These films had tensile strengths of 79–117 MPa, elongation-at-break of 7–61%, and initial moduli of 2.2–3.0 GPa. The wide-angle X-ray diffraction revealed that some polymers are partially crystalline. The glass transition temperatures of some polymers could be determined with the help of differential scanning calorimetry (DSC) traces, which were recorded in the range 232–300°C. All the poly(amide–imide)s exhibited no appreciable decomposition below 450°C, and their 10% weight loss temperatures were recorded in the range 511–577°C in nitrogen and 497–601°C in air. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 919–927, 1998     

Highly soluble and optically transparent poly (ether imide)s based on 2,6‐ or 2,7‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride and aromatic bis(ether amine)s bearing trifluoromethyl groups

Two series of novel fluorinated poly(ether imide)s (coded IIIA and IIIB ) were prepared from 2,6‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride and 2,7‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride, respectively, with various trifluoromethyl‐substituted aromatic bis(ether amine)s by a standard two‐step process with thermal or chemical imidization of the poly(amic acid) precursors. These fluorinated poly(ether imide)s showed good solubility in many organic solvents and could be solution‐cast into transparent, flexible, and tough films. These films were nearly colorless, with an ultraviolet–visible absorption edge of 364–386 nm. They also showed good thermal stability with glass‐transition temperatures of 221–298 °C, 10% weight loss temperatures in excess of 489 °C, and char yields at 800 °C in nitrogen greater than 50%. The 2,7‐substituted IIIB series also showed better solubility and higher transparency than the isomeric 2,6‐substituted IIIA series. In comparison with nonfluorinated poly (ether imide)s, the fluorinated IIIA and IIIB series showed better solubility, higher transparency, and lower dielectric constants and water absorption. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5909–5922, 2006     

High optical transparency and low dielectric constant of novel organosoluble poly(ether ketone amide)s derived from an unsymmetrical diamine containing trifluoromethyl and methyl pendant groups

A series of novel fluorinated poly(ether ketone amide)s (PEKAs) were prepared from an unsymmetrical aromatic diamine, (4′-(4″-amino-2″-trifluoromethylphenoxy)-3′,5′-dimethylphenyl)(4-aminophenyl)-methanone (1), with various aromatic dicarboxylic acids using the phosphorylation polycondensation technique. The PEKAs had inherent viscosities ranging from 0.43 to 0.65 dl/g. All the fluorinated PEKAs could be soluble in many polar organic solvents such as N-methyl-2-pyrrolidinone (NMP), N,N′-dimethylacetamide (DMAc), N,N′-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF). Flexible and tough polymer films could be prepared by casting from DMAc solvent. The PEKA films exhibited high optical transparency with a cutoff wavelength of 354–365 nm and good mechanical properties with tensile strengths of 78–98 MPa and elongations at break of 11.5–18.5%. They showed glass-transition temperatures in the range of 288−323 °C and the onset decomposition temperatures in the range of 450−461 °C in nitrogen atmosphere. Meanwhile, the PEKA films possessed low dielectric constants of 1.98–2.71 at 1 MHz and low moisture absorption (<2%). Due to their properties, the fluorinated PEKAs could be considered as photoelectric and microelectronic materials.     

Heat-resistant and soluble fluorinated poly(amide imide)s based on non-coplanar ortho-linked diimide-dicarboxylic acid

A series of novel fluorinated heat-resistant poly(amide imide)s (PAIS) based on non-coplanar diimide-diacid monomer (DIDA) were synthesized and characterized. The poly(amide imide)s were obtained in high yields and possessed inherent viscosities in the range of 0.47-0.91 dL g⁻¹. All of the polymers were amorphous in nature, showed outstanding solubility and could be readily soluble in common organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidinoned, dimethyl sulfoxide, N,N-dimethylformamide, pyridine and tetrahydrofuran. Glass transition temperatures were in the range of 221-263 °C, as determined by differential scanning calorimetry. Degradation temperatures for 10% weight loss occurred all above 520 °C and char yields was more than 50% at 700 °C in nitrogen atmosphere. Moreover, these PAIs possessed low refractive indexes (n = 1.58-1.59), birefringence (Δn = 0.008-0.013), and dielectric constants (? ≈ 2.5) due to the trifluoromethyl pendent groups and ortho-catenated aromatic rings that interrupt chain packing and increase free volume.     

Novel organosoluble and colorless poly(ether imide)s based on 3,3‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]phthalide dianhydride and aromatic bis(ether amine)s bearing pendent trifluoromethyl groups

A novel series of colorless and highly organosoluble poly(ether imide)s were prepared from 3,3‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]phthalide dianhydride with various fluorinated aromatic bis(ether amine)s via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by cyclodehydration to produce the polymer films. The poly(ether imide)s showed excellent solubility, with most of them dissoluble at a concentration of 10 wt % in amide polar solvents, in ether‐type solvents, and even in chlorinated solvents. Their films had a cutoff wavelength between 358 and 373 nm, and the yellowness index ranged from 3.1 to 9.5. The glass‐transition temperatures of the poly(ether imide) series were recorded between 237 and 297 °C, the decomposition temperatures at 10% weight loss were all above 494 °C, and the residue was more than 54% at 800 °C in nitrogen. These films showed high tensile strength and also were characterized by higher solubility, lighter color, and lower dielectric constants and moisture absorption than an analogous nonfluorinated polyimide series. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3140–3152, 2006     

Novel organosoluble and colorless poly(ether imide)s based on 1,1-bis[4-(3,4-dicarboxyphenoxy)phenyl]cyclohexane dianhydride and trifluoromethyl-substituted aromatic bis(ether amine)s

A series of novel fluorinated poly(ether imide)s (IV) having inherent viscosities of 0.70-1.08 dL/g were prepared from 1,1-bis[4-(3,4-dicarboxyphenoxy)phenyl]cyclohexane dianhydride (I) and various trifluoromethyl (CF₃)-substituted aromatic bis(ether amine)s II_a-g by a standard two-step process with thermal and chemical imidization of poly(amic acid) precursors. These poly(ether imide)s showed excellent solubility in many organic solvents and could be solution-cast into transparent, flexible, and tough films. These films were essentially colorless, with an ultraviolet-visible absorption edge of 375-380 nm and a very low b^∗ value (a yellowness index) of 5.5-7.3. They also showed good thermal stability with glass-transition temperatures of 207-269 °C, 10% weight loss temperatures in excess of 474 °C, and char yields at 800 °C in nitrogen more than 62%. In comparison with analogous V series poly(ether imide)s without the -CF₃ substituents, the IV series polymers showed better solubility, lower color intensity, and lower dielectric constants.     

Synthesis and characterization of novel fluorinated polyimides derived from 4-phenyl-2,6-bis[4-(4′-amino-2′-trifluoromethyl-phenoxy)phenyl]pyridine and dianhydrides

A series of organo-soluble polyimides were prepared from a novel fluorinated diamine monomer, 4-phenyl-2,6-bis[4-(4′-amino-2′-trifluoromethylphenoxy)phenyl]pyridine and various commercial aromatic dianhydrides. These polyimides had good solubility in common organic solvents. The obtained strong and flexible PI films exhibited excellent thermal stability with the decomposition temperature (at 5% weight loss) of above 561 °C and the glass transition temperature in the range of 258-312 °C. Moreover, the polymer films showed good electrical insulating property, low dielectric constant and low water uptake due to the introduction of fluorinated substitutes in the polymer backbone. The remarkable combined features ensure these polymers to be ideal candidate materials for advanced microelectronic industry and other related applications.     

Synthesis and characterization of new fluorene‐based poly(ether imide)s

A novel bis(ether anhydride) monomer, 9,9‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]fluorene dianhydride (4), was synthesized from the nitrodisplacement of 4‐nitrophthalonitrile by the bisphenoxide ion of 9,9‐bis(4‐hydroxyphenyl)fluorene (1), followed by alkaline hydrolysis of the intermediate tetranitrile and dehydration of the resulting tetracarboxylic acid. A series of poly(ether imide)s bearing the fluorenylidene group were prepared from the bis(ether anhydride) 4 with various aromatic diamines 5a–i via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s 6a–i followed by thermal cyclodehydration to the polyimides 7a–i. The intermediate poly(amic acid)s had inherent viscosities in the range of 0.39–1.57 dL/g and afforded flexible and tough films by solution‐casting. Except for those derived from p‐phenylenediamine, m‐phenylenediamine, and benzidine, all other poly(amic acid) films could be thermally transformed into flexible and tough polyimide films. The glass transition temperatures (T_g) of these poly(ether imide)s were recorded between 238–306°C with the help of differential scanning calorimetry (DSC), and the softening temperatures (T_s) determined by thermomechanical analysis (TMA) stayed in the range of 231–301°C. Decomposition temperatures for 10% weight loss all occurred above 540°C in an air or a nitrogen atmosphere. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1403–1412, 1999     

Effect of introduction of heterocyclic moieties into polymer backbone on gas transport properties of fluorinated poly(ether imide) membranes

The effects of incorporation of heterocyclic moieties into fluorinated poly(ether imide) membranes on their gas transport properties were investigated. Four novel fluorinated poly(ether imide) (PEI) membranes were prepared from four different bis(ether amine)s namely, 4,4-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]biphenyl (BAQP); 1,4-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl] benzene (BATP); 2,6-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]pyridine (BAPy) and 2,5-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]thiophene (BATh), and a fluorinated dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane (6FDA) as a common dianhydride. Gas transport properties of these membranes were measured to investigate the effect of chemical structure on gas permeation and diffusion processes over four different gases (e.g., CH₄, N₂, O₂ and CO₂) at different temperatures (e.g., 35, 45 and 55 °C) at an applied pressure of 3.5 bar. It has been found that at 35 °C the permselectivities of BAPy and BATh based polymeric membranes (6.4 and 6.6, respectively) toward O₂ relative to N₂ are higher in comparison to BAQP and BATP (5.5 and 5.3, respectively) containing PEI membranes. The permeability coefficient of CO₂ for BAPy and BATh (51.92 and 45.31, respectively at 35 °C) based PEI membranes were observed to be much higher than BAQP and BATP based membranes (36.61 and 33.51, respectively at 35 °C) with comparable selectivity values of CO₂ relative to CH₄. All these membranes exhibit higher CO₂/CH₄ selectivity than those of common glassy polymers e.g., cellulose acetate, polysulfone and polycarbonate. The order of permeability of these gases was found as CO₂ > O₂ > N₂ > CH₄. The temperature dependency of permeation and diffusion processes enables to calculate the activation energies of the permeation and diffusion processes for these four different gases through four PEI membranes.     

Synthesis and characterization of new poly(amide–imide)s from 1,4-bis(4-trimellitimidophenoxy)-2-tert-butylbenzene with various diamines

New poly(amide–imide)s were prepared from a diimide–dicarboxylic acid, 1,4-bis(4-trimellitimidophenoxy)-2-tert-butylbenzene ( BTTB ), with various diamines by the direct polycondensation in N-methyl-2-pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The new diimide–dicarboxylic acid BTTB containing an ether linkage and tert-butyl substituent was synthesized by the condensation reaction of 1,4-bis(4-aminophenoxy)-2-tert-butylbenzene with trimellitic anhydride. All the polymers were obtained in quantitative yields with inherent viscosities of 0.62–1.06 dL g⁻¹. The polymers were amorphous, and most of them were readily soluble in aprotic polar solvents such as NMP, N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF), as well as in less polar solvents such as dimethyl sulfoxide (DMSO), m-cresol, pyridine, and γ-butyrolactone, and also even in tetrahydrofuran. The glass transition temperatures of the polymers were determined by DSC method, and they were in the range of 238–279°C. These polymers were stable up to 408–449°C in air and 451–483°C in nitrogen and lose 10% weight in the range of 479–525°C in air and 480–528°C in nitrogen atmosphere. The polymer films had a tensile strength range of 71–115 MPa, an elongation at break range of 4–14%, and a tensile modulus range of 2.3–3.1 GPa. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2301–2307, 1998     

Synthesis and characterization of new highly organosoluble poly(etherimide)s derived from 1,1‐bis{4‐[4‐(3,4‐dicarboxyphenoxy)phenyl]‐4‐phenylcyclohexane} dianhydride

A new bulky pendent bis(ether anhydride), 1,1‐bis[4‐(4‐dicarboxyphenoxy)phenyl]‐4‐phenylcyclohexane dianhydride, was prepared in three steps, starting from the nitrodisplacement of 1,1‐bis(4‐hydroxyphenyl)‐4‐phenylcyclohexane with 4‐nitrophthalonitrile to form bis(ether dinitrile), followed by alkaline hydrolysis of the bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). A series of new poly(ether imide)s were prepared from the bis(ether anhydride) with various diamines by a conventional two‐stage synthesis including polyaddition and subsequent chemical cyclodehydration. The resulting poly(ether imide)s had inherent viscosities of 0.50–0.73 dL g^?1. The gel permeation chromatography measurements revealed that the polymers had number‐average and weight‐average molecular weights of up to 57,000 and 130,000, respectively. All the polymers showed typical amorphous diffraction patterns. All of the poly(ether imide)s showed excellent solubility in comparison with the other polyimides derived from adamantane, norbornane, cyclododecane, and methanohexahydroindane and were readily dissolved in various solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, pyridine, cyclohexanone, tetrahydrofuran, and even chloroform. These polymers had glass‐transition temperatures of 226–255 °C. Most of the polymers could be dissolved in chloroform in as high as a 30 wt % concentration. Thermogravimetric analysis showed that all polymers were stable up to 450 °C, with 10% weight losses recorded from 458 to 497 °C in nitrogen. These transparent, tough, and flexible polymer films could be obtained by solution casting from DMAc solutions. These polymer films had tensile strengths of 79–103 MPa and tensile moduli of 1.5–2.1 GPa. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2066–2074, 2002     

Novel soluble fluorinated aromatic polyamides derived from 2-(4-trifluoromethylphenoxy)terephthaloyl chloride with various aromatic diamines

A series of novel fluorinated aromatic polyamides derived from a new monomer, 2-(4-trifluoromethylphenoxy)terephthaloyl chloride (TFTPC), with various aromatic diamines were synthesized and characterized. The polyamides were obtained in high yields and moderately high inherent viscosities ranging from 1.07 to 1.16 dL/g. All the polyamides were amorphous and readily soluble in many organic solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N′-dimethylacetamide (DMAc), N,N′-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and could afford flexible and tough films via solution casting. The cast films exhibited good mechanical properties with tensile strengths of 82.8-107.3 MPa, elongation at break of 4.1-7.2%, and tensile modulus of 2.26-3.95 GPa. These polyamide films also exhibited good thermal stability with the glass transition temperature of 222-294 °C, the temperature at 5% weight loss of 442-472 °C in nitrogen. They exhibited low dielectric constants ranging from 3.25 to 3.39 (1 MHz), low moisture absorption in the range of 1.32-2.45%, high transparency with an ultraviolet-visible absorption cut-off wavelength in the 330-371 nm range, and excellent electrical properties.