Synthesis and Characterization of Fluorinated Polyimide Derived from 3,3′‐Diisopropyl‐4,4′‐diaminodiphenyl‐3′′,4′′‐difluorophenylmethane

A novel aromatic diamine monomer, 3,3′‐diisopropyl‐4,4′‐diaminodiphenyl‐3′′,4′′‐difluorophenylmethane (PAFM), was successfully synthesized by coupling of 2‐isopropylaniline and 3,4‐difluorobenzaldehyde. The aromatic diamine was adopted to synthesize a series of fluorinated polyimides by polycondensation with various dianhydrides: pyromellitic dianhydride (PMDA), 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), 4,4′‐oxydiphthalic anhydride (ODPA) and 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) via the conventional one‐step method. These polyimides presented excellent solubility in common organic solvents, such as N,N‐dimethylformamide (DMF), N,N‐dimethyl acetamide (DMAc), dimethyl sulfoxide (DMSO), N‐methyl‐2‐pyrrolidone (NMP), chloroform (CHCl₃), tetrahydrofuran (THF) and so on. The glass transition temperatures (T_g) of fluorinated polyimides were in the range of 260–306°C and the temperature at 10% weight loss in the range of 474–502°C. Their films showed the cut‐off wavelengths of 330–361 nm and higher than 80% transparency in a wavelength range of 385–463 nm. Moreover, polymer films exhibited low dielectric properties in the range of 2.76–2.96 at 1 MHz, as well as prominent mechanical properties with tensile strengths of 66.7–97.4 MPa, a tensile modulus of 1.7–2.1 GPa and elongation at break of 7.2%–12.9%. The polymer films also showed outstanding hydrophobicity with the contact angle in the range of 91.2°–97.9°.     

Novel aromatic polyamides and polyimides functionalized with 4‐tert‐butyltriphenylamine groups

A new triphenylamine‐containing diamine monomer, 4,4′‐diamino‐4″‐tert‐butyltriphenylamine, was successfully synthesized by the cesium fluoride‐mediated N,N‐diarylation of 4‐tert‐butylaniline with 4‐fluoronitrobenzene, followed by the reduction of the nitro group. The obtained diamine monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce two series of novel triphenylamine‐based polyamides and polyimides with pendent tert‐butyl substituents. Most of the polymers were readily soluble in polar organic solvents, such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide (DMAc), and could be solution cast into tough and flexible polymer films. These polymers showed high glass transition temperatures between 282 and 320 °C, and they were fairly stable up to a temperature above 450 °C (for polyamides) or 500 °C (for polyimides). These polymers exhibited UV absorption maxima around 308 to 361 nm. The photoluminescence spectra of the polyamides in DMAc exhibited a peak emission wavelength in the blue at 421–433 nm. Cyclic voltammograms of polyamides and polyimides showed an oxidation wave at 1.0–1.1 V versus Ag/AgCl in an acetonitrile solution. All the polyamides and polyimides exhibited excellent reversibility of electrochromic characteristics by continuous several cyclic scans between 0.0 and 1.1–1.3 V, with a color change from the original pale yellowish neutral form to the green or blue oxidized forms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4579–4592, 2006     

Preparation and properties of new polyimides and polyamides based on 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)naphthalene

A novel, trifluoromethyl‐substituted, bis(ether amine) monomer, 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)naphthalene, was synthesized through the nucleophilic displacement of 2‐chloro‐5‐nitrobenzotrifluoride with 1,4‐dihydroxynaphthalene in the presence of potassium carbonate in dimethyl sulfoxide, followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new fluorine‐containing polyimides with inherent viscosities of 0.57–0.91 dL/g were prepared by reacting the diamine with six commercially available aromatic dianhydrides via a conventional, two‐step thermal or chemical imidization method. Most of the resulting polyimides were soluble in strong polar solvents such as N‐methylpyrrolidone and N,N‐dimethylacetamide (DMAc). All the polyimides afforded transparent, flexible, and strong films with good tensile properties. These polyimides exhibited glass‐transition temperatures (T_g's) (by DSC) and softening temperatures (by thermomechanical analysis) in the ranges of 252–315 and 254–301 °C, respectively. Decomposition temperatures for 5% weight loss all occurred above 500 °C in both air and nitrogen atmospheres. The dielectric constants of these polyimides ranged from 3.03 to 3.71 at 1 MHz. In addition, a series of new, fluorinated polyamides with inherent viscosities of 0.32–0.62 dL/g were prepared by the direct polycondensation reaction the diamine with various aromatic dicarboxylic acids by means of triphenyl phosphite and pyridine. All the polyamides were soluble in polar solvents such as DMAc and could be solution‐cast into tough and flexible films. These polyamides had T_g's between 228 and 256 °C and 10% weight‐loss temperatures above 400 °C in nitrogen or air. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2377–2394, 2004     

Synthesis and properties of fluorinated polyimides. 1. Derived from novel 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl

A new diamine monomer, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl (ATFT) was synthesized that led to a number of novel fluorinated polyimides by solution as well as thermal imidization routes when reacted with different commercially available dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), or 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides ATFT/BTDA and ATFT/6FDA derived from both routes were soluble in several organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide. The polyimide ATFT/PMDA was only soluble in N‐methylpyrollidone. The polyimide films had low water absorption of 0.3–0.7%, low dielectric constants of 2.72–3.3 at 1 Hz, refractive indices of 1.594–1.647 at 589.3 nm, and optical transparency >85%. These polyimides showed very high thermal stability with decomposition temperatures (5% weight loss) up to 532 °C in air and good isothermal stability; only 7% weight loss occurred at 400 °C after 7 h, and less than 0.6% weight loss was observed at 315 °C for 5 h. Transparent thin films of these polyimides exhibited tensile strengths up to 112 MPa, a modulus of elasticity up to 3.05 GPa, and elongation at break up to 21% depending on the repeating unit structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1016–1027, 2002     

Synthesis and properties of fluorinated polyimides based on 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐2,5‐di‐tert‐butylbenzene and various aromatic dianhydrides

A novel fluorinated diamine monomer, 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐2,5‐di‐tert‐butylbenzene ( 2 ), was prepared through the nucleophilic substitution reaction of 2‐chloro‐5‐nitrobenzotrifluoride and 2,5‐di‐tert‐butylhydroquinone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Fluorinated polyimides ( 5a – 5f ) were synthesized from diamine 2 and various aromatic dianhydrides ( 3a – 3f ) via thermal or chemical imidization. These polymers had inherent viscosities of 0.77–1.01 dL/g. The 5 series polyimides were soluble in N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, and N,N‐dimethylformamide and were even soluble in dioxane, tetrahydrofuran, and dichloromethane. 5 (C) showed cutoff wavelengths between 363 and 404 nm and yellowness index (b*) values of 6.5–40.2. The polyimide films had tensile strengths of 93–114 MPa, elongations to break of 9–12%, and initial moduli of 1.7–2.1 GPa. The glass‐transition temperatures were 255–288 °C. The temperatures of 10% weight loss were all above 460 °C in air or nitrogen atmospheres. In comparison with a nonfluorinated polyimide series based on 1,4‐bis(4‐aminophenoxy)‐2,5‐di‐tert‐butylbenzene, the 5 series showed better solubility and lower color intensity, dielectric constants, and moisture absorption. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2272–2284, 2004     

Highly soluble fluorinated polyimides based on an asymmetric bis(ether amine): 1,7‐bis(4‐amino‐2‐trifluoromethylphenoxy)naphthalene

A novel structurally asymmetric bis(ether amine) monomer containing trifluoromethyl groups, 1,7‐bis(4‐amino‐2‐trifluoromethylphenoxy)naphthalene, was prepared through the nucleophilic substitution reaction of 2‐chloro‐5‐nitrobenzotrifluoride and 1,7‐dihydroxynaphthalene in the presence of potassium carbonate in N‐methyl‐2‐pyrrolidone (NMP), followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new fluorine‐containing polyimides were synthesized from the diamine with various commercially available aromatic tetracarboxylic dianhydrides using a two‐stage process with thermal or chemical imidization method. The intermediate poly(amic acid)s had inherent viscosities between 0.93 and 1.93 dL/g. Most of the polyimides obtained from both routes were readily soluble in many organic solvents such as NMP and N,N‐dimethylacetamide (DMAc). All the polyimides could afford transparent, flexible, and strong films with low moisture absorptions of 0.29–0.69%, low dielectric constants of 2.81–3.23 at 10 kHz, and an ultraviolet‐visible absorption cutoff wavelength at 358–423 nm. The glass‐transition temperatures (T_gs) (by DSC) and softening temperatures (by thermomechanical analysis) of the polyimides were recorded in the range of 222–271 °C and 210–266 °C, respectively. Decomposition temperatures for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. For a comparative study, some properties of the present polyimides will be compared with those of structurally related ones derived from 1,7‐bis(4‐aminophenoxy)naphthalene and 1,5‐bis(4‐amino‐2‐trifluoromethylphenoxy)naphthalene. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1756–1770, 2009     

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     

Synthesis and characterization of new soluble aromatic polyamides based on 4‐(1‐adamantyl)‐1, 3‐bis(4‐aminophenoxy)benzene

A set of new aromatic polyamides were synthesized by the direct phosphorylation condensation of 4‐(1‐adamantyl)‐1,3‐bis‐(4‐aminophenoxy)benzene with various diacids. The polymers were produced with high yields and moderate to high inherent viscosities (0.43–1.03 dL/g), and the weight‐average molecular weights and number‐average molecular weights, determined by gel permeation chromatography, were in the range of 37,000–93,000 and 12,000–59,000, respectively. The polyamides were essentially amorphous and soluble in a variety of solvents such as N,N‐dimethylacetamide (DMAc), cyclohexanone, and tetrahydrofuran. They showed glass‐transition temperatures in the range of 240–300 °C (differential scanning calorimetry) and 10% weight‐loss temperatures over 450 °C, as revealed by thermogravimetric analysis in nitrogen. All the polymers gave strong films via casting from DMAc solutions, and these films exhibited good mechanical properties, with tensile strengths in the range of 77–92 MPa and tensile moduli between 1.5 and 2.5 GPa. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1014–1023, 2000     

Synthesis and properties of new soluble aromatic polyamides and polyimides on the basis of N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine

A new N‐phenylated amide (N‐phenylamide) unit containing aromatic diamine, N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine, was prepared by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 3‐nitrobenzoyl chloride, followed by catalytic reduction. Two series of organosoluble aromatic poly(N‐phenylamide‐imide)s and poly(N‐phenylamide‐amide)s with inherent viscosities of 0.58–0.82 and 0.56–1.21 dL/g were prepared by a conventional two‐stage method and the direct phosphorylation polycondensation, respectively, from the diamine with various aromatic dianhydrides and aromatic dicarboxylic acids. All polyimides and polyamides are amorphous and readily soluble in many organic solvents such as N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with high tensile strengths. These polyimides and polyamides had glass‐transition temperatures in the ranges of 230–258 and 196–229 °C, respectively. Decomposition temperatures of the polyimides for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2564–2574, 2002     

Polyimides based on 2,5‐bis(4‐aminophenoxy)biphenyl

A diamine monomer II , 2,5‐bis(4‐aminophenoxy)biphenyl, was prepared through a nucleophilic substitution reaction of phenylhydroquinone and p‐chloronitrobenzene in the presence of potassium carbonate in N,N‐dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. A series of all‐aromatic, organosoluble polyimides bearing pendent phenyl groups were synthesized from the diamine with six kinds of commercial dianhydrides via a conventional two‐stage process. For improving solubility of polypyromellitimide, copolypyromellitimides with arbitrary solubilities were prepared from II and a pair of dianhydrides, which were mixed at certain molar ratios. These polymers showed good solubilities in N‐methyl‐2‐pyrrolidone and m‐cresol. The softening temperatures of these polyimides were recorded between 206 and 269 °C. Polymers had glass‐transition temperatures at 230–286 °C and 10% weight‐loss temperatures above 521 °C in air or nitrogen atmospheres. Their films had high tensile moduli and strengths. Excellent properties of these polyimides are attributed to the incorporation of the pendent phenyl group in diamine II . © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 429–438, 2002; DOI 10.1002/pola.10116     

Novel,organosoluble, light‐colored fluorinated polyimides based on 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl or 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐1,1′‐binaphthyl

Two series of fluorinated polyimides were prepared from 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl ( 2 ) and 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐1,1′‐binaphthyl ( 4 ) with various aromatic dianhydrides via a conventional, two‐step procedure that included a ring‐opening polyaddition to give poly(amic acid)s, followed by chemical or thermal cyclodehydration. The inherent viscosities of the polyimides ranged from 0.54 to 0.73 and 0.19 to 0.36 dL/g, respectively. All the fluorinated polyimides were soluble in many polar organic solvents, such as N,N‐dimethylacetamide and N‐methylpyrrolidone, and afforded transparent and light‐colored films via solution‐casting. These polyimides showed glass‐transition temperatures in the ranges of 222–280 and 257–351 °C by DSC, softening temperatures in the range of 264–301 °C by thermomechanical analysis, and a decomposition temperature for 10% weight loss above 520 °C both in nitrogen and air atmospheres. The polyimides had low moisture absorptions of 0.23–0.58%, low dielectric constants of 2.84–3.61 at 10 kHz, and an ultraviolet–visible absorption cutoff wavelength at 351–434 nm. Copolyimides derived from the same dianhydrides with an equimolar mixture of 4,4′‐oxydianiline and diamine 2 or 4 were also prepared and characterized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2416–2431, 2004     

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     

Syntheses and properties of organosoluble polyimides based on 5,5′‐bis[4‐(4‐aminophenoxy)phenyl]‐4, 7‐methanohexahydroindan

A series of organosoluble aromatic polyimides (PIs) was synthesized from 5,5′‐bis[4‐(4‐aminophenoxy)phenyl]‐4,7‐methanohexahydroindan (3) and commercial available aromatic dianhydrides such as 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), 4,4′‐oxydiphthalic anhydride (ODPA), 4,4′‐sulfonyl diphthalic anhydride (SDPA), or 2,2′‐bis(3,4‐dicarboxyphenyl) hexafluoropropanic dianhydride (6FDA). PIs (III_c–f), which were synthesized by direct polymerization in m‐cresol, had inherent viscosities of 0.83–1.05 dL/g. These polymers could easily be dissolved in N,N′‐dimethylacetamide (DMAc), N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide (DMF), pyridine, m‐cresol, and dichloromethane. Whereas copolymerization was proceeded with equivalent molar ratios of pyromellitic dianhydride (PMDA)/6FDA, 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA)/6FDA, or BTDA/SDPA, or ½ for PMDA/SDPA, copolyimides (co‐PIs), derived from 3 and mixed dianhydrides, were soluble in NMP. All the soluble PIs could form transparent, flexible, and tough films, and they showed amorphous characteristics. These films had tensile strengths of 88–111 MPa, elongations at break of 5–10% and initial moduli of 2.01–2.67 GPa. The glass transition temperatures of these polymers were in the range of 252–311°C. Except for III_e, the 10% weight loss temperatures (T_d) of PIs were above 500°C, and the amount of carbonized residues of the PIs at 800°C in nitrogen atmosphere were above 50%. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1681–1691, 1999     

Organosoluble and light‐colored fluorinated polyimides from 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl and aromatic dianhydrides

A novel fluorinated diamine monomer based on 4,4′‐biphenol was synthesized via a straightforward, high‐yielding two‐step procedure. 4,4′‐Biphenol was reacted with 2‐chloro‐5‐nitrobenzotrifluoride in the presence of potassium carbonate to yield the intermediate dinitro compound, which was subsequently reduced to afford the fluorinated diamine, 4,4′‐bis(4‐amino‐3‐trifluoromethylphenoxy)biphenyl. A series of organosoluble fluorinated polyimides were prepared from the diamine with various aromatic dianhydrides via a conventional two‐step thermal imidization method. All polyimides were soluble in strong dipolar solvents such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide. The polyimides showed excellent thermal and thermooxidative stability and good mechanical properties. No significant weight loss was observed below a temperature of 520 °C in nitrogen or in air, and the glass‐transition temperatures ranged from 247 to 313 °C. Low dielectric constants (2.57–3.65 at 10 kHz), low moisture absorption (0.1–0.7 wt %), and low color intensity were also observed. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 524–534, 2002; DOI 10.1002/pola.10113     

Novel Non‐Coplanar and Tertbutyl‐Substituted Polyimides: Solubility,Optical, Thermal and Dielectric Properties

A novel aromatic diamine monomer bearing tertbutyl and 4‐tertbutylphenyl groups, 3,3′‐ditertbutyl‐4,4′‐diaminodiphenyl‐4′′‐tertbutylphenylmethane (TADBP), was prepared and characterized. A series of non‐coplanar polyimides (PIs) were synthesized via a conventional one‐step polycondensation from TADBP and various aromatic dianhydrides including pyromellitic dianhydride (PMDA), 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), 4,4′‐oxydiphthalic anhydride (OPDA), 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) and 4,4′‐(hexafluoroisopropylidene)dipthalic anhydride (6FDA). All PIs exhibit excellent solubility in common organic solvents such as N,N‐dimethylformamide (DMF), N,N‐dimethylacetamide (DMAc), N‐methyl‐2‐pyrrolidone (NMP), dimethyl sulfoxide (DMSO), chloroform (CHCl₃), tetrahydrofuran (THF), and so on. Furthermore, the obtained transparent, strong and flexible polyimide films present good thermal stability and outstanding optical properties. Their glass transition temperatures (T_gs) are in the range of 298 to 347°C, and 10% weight loss temperatures are in excess of 490°C with more than 53% char yield at 800°C in nitrogen. All the polyimides can be cast into transparent and flexible films with tensile strength of 80.5–101 MPa, elongation at break of 8.4%–10.5%, and Young's modulus of 2.3–2.8 GPa. Meanwhile, the PIs show the cutoff wavelengths of 302–356 nm, as well as low moisture absorption (0.30% –0.55%) and low dielectric constant (2.78–3.12 at 1 MHz).     

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 characterization of novel soluble triphenylamine‐containing aromatic polyamides based on N,N′‐bis(4‐aminophenyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine

A new triphenylamine‐containing aromatic diamine, N, N′‐bis(4‐aminophenyl)‐N, N′‐diphenyl‐1,4‐phenylenediamine, was prepared by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 4‐fluoronitrobenzene, followed by catalytic reduction. A series of novel aromatic polyamides with triphenylamine units were prepared from the diamine and various aromatic dicarboxylic acids or their diacid chlorides via the direct phosphorylation polycondensation or low‐temperature solution polycondensation. All the polyamides were amorphous and readily soluble in many organic solvents such as N, N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass‐transition temperatures (257–287 °C), 10% weight‐loss temperatures in excess of 550 °C, and char yields at 800 °C in nitrogen higher than 72%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2810–2818, 2002     

Synthesis and characterization of new soluble poly(amide‐imide)s derived from 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]hexafluoropropane

A series of new soluble poly(amide‐imide)s were prepared from the diimide‐dicarboxylic acid 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]hexafluoropropane with various diamines by direct polycondensation in N‐methyl‐2‐pyrrolidinone containing CaCl₂ with triphenyl phosphite and pyridine as condensing agents. All the polymers were obtained in quantitative yields with inherent viscosities of 0.52–0.86 dL · g^?1. The poly(amide‐imide)s showed an amorphous nature and were readily soluble in various solvents, such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, pyridine, and cyclohexanone. Tough and flexible films were obtained through casting from DMAc solutions. These polymer films had tensile strengths of 71–107 MPa and a tensile modulus range of 1.6–2.7 GPa. The glass‐transition temperatures of the polymers were determined by a differential scanning calorimetry method, and they ranged from 242 to 279 °C. These polymers were fairly stable up to a temperature around or above 400 °C, and they lost 10% of their weight from 480 to 536 °C and 486 to 537 °C in nitrogen and air, respectively. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3498–3504, 2001     

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 autophotosensitive hyperbranched polyimides based on 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 1,3,5‐tris(4‐aminophenoxy)benzene via end capping of the terminal anhydride groups by ortho‐alkyl aniline

Benzophenone‐containing, anhydride‐terminated hyperbranched poly(amic acid)s were end‐capped by ortho‐alkyl aniline in situ and then chemically imidized, yielding autophotosensitive hyperbranched polyimides. The polyimides were soluble in strong polar solvents, such as N‐methyl‐2‐pyrrolidone, N‐dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. Thermogravimetric analysis revealed their excellent thermal stability, with a 5 wt % thermal loss temperature in the range of 527–548 °C and a10 wt % thermal loss temperature in the range of 562–583 °C. The strong absorption of the polyimide films in ultraviolet–visible spectra at 365 nm indicated that the hyperbranched polyimides were patternable. Highly resolved images with a line width of 6 μm were developed by ultraviolet exposure of the polymer films. A well‐defined image with lines as thin as 3 μm was also patterned, but the lines were rounded at the edges. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2026–2035, 2003