Flexible Polyimide Films Research Articles

Synthesis and properties of organosoluble poly(ether imide)s containing 4,4′(octahydro-4,7-methano-5H-inden-5-ylidene) cardo group

A series of organosoluble aromatic poly(ether imide)s (PEIs) VIIa-k were synthesized from 4,4′-[(octahydro-4,7-methano-5H-inden-5-ylidene)bis(1,4-phenylene)dioxy] diphthalic dianhydride (IV) and various aromatic diamines. PEIs synthesized through two-stage polymerization had inherent viscosities of 0.51–0.64 dL/g. This series of polymers could also be synthesized from IV and diamines in a small amount of refluxing m-cresol in a one-step process and had inherent viscosities of 0.65–0.87 dL/g. For the low melting point diamines (Vj and Vk), polymers could be obtained by bulk polymerization and had inherent viscosities of 0.36 and 0.41 dL/g. Polymers showed good organosolubility and could be cast into transparent, flexible, and tough polyimide films with good tensile properties. These PEIs had glass transition temperatures among 203–281°C. Thermogravimetric analyses established that these polymers were fairly stable up to 430°C, and the 10% weight loss temperatures were recorded in the range of 473–503°C in nitrogen and 481–512°C in air atmosphere. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 987–996, 1999

Synthesis and characterization of new cardo polyimides prepared from 5,5‐Bis[4‐(4‐aminophenoxy)phenyl]‐4,7‐methanohexahydroindane

A new cardo diamine monomer, 5,5-bis[4-(4-aminophenoxy)phenyl]-4,7-methanohexahydroindane (II), was prepared in two steps with high yield. The monomer was reacted with six different aromatic tetracarboxylic dianhydrides in N,N-dimethylacetamide (DMAc) to obtain the corresponding cardo polyimides via the poly(amic acid) precursors and thermal or chemical imidization. All the poly(amic acid)s could be cast from their DMAc solutions and thermally converted into transparent, flexible, and tough polyimide films which were further characterized by x-ray and mechanical analysis. All of the polymers were amorphous and the polyimide films had a tensile strength range of 89–123 MPa, an elongation at break range of 6–10%, and a tensile modulus range of 1.9–2.5 GPa. Polymers Vc, Ve, and Vf exhibited good solubility in a variety of solvents such as N-methyl-2-pyrrolidinone (NMP), DMAc, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, γ-butyrolactone, and even in tetrahydrofuran and chloroform. These polyimides showed glass-transition temperatures between 274 and 299°C and decomposition temperatures at 10% mass loss temperatures ranging from 490 to 521°C and 499 to 532°C in nitrogen and air atmospheres, respectively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2815–2821, 1999

Synthesis and characterization of new cardo polyimides prepared from 5,5-Bis[4-(4-aminophenoxy)phenyl]-4,7-methanohexahydroindane

A new cardo diamine monomer, 5,5-bis[4-(4-aminophenoxy)phenyl]-4,7-methanohexahydroindane (II), was prepared in two steps with high yield. The monomer was reacted with six different aromatic tetracarboxylic dianhydrides in N,N-dimethylacetamide (DMAc) to obtain the corresponding cardo polyimides via the poly(amic acid) precursors and thermal or chemical imidization. All the poly(amic acid)s could be cast from their DMAc solutions and thermally converted into transparent, flexible, and tough polyimide films which were further characterized by x-ray and mechanical analysis. All of the polymers were amorphous and the polyimide films had a tensile strength range of 89–123 MPa, an elongation at break range of 6–10%, and a tensile modulus range of 1.9–2.5 GPa. Polymers Vc, Ve, and Vf exhibited good solubility in a variety of solvents such as N-methyl-2-pyrrolidinone (NMP), DMAc, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, γ-butyrolactone, and even in tetrahydrofuran and chloroform. These polyimides showed glass-transition temperatures between 274 and 299°C and decomposition temperatures at 10% mass loss temperatures ranging from 490 to 521°C and 499 to 532°C in nitrogen and air atmospheres, respectively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2815–2821, 1999

Ladder-type polyimides based on diaminodibenzofurane

Two diaminodibenzofuranes with different configurations, 2,8-diaminodibenzofurane ( 2a) and the 2,7-isomer ( 2b), were synthesized from dibenzofurane. The isomers were isolated using chromatography and their structures were confirmed based on their NMR spectra. The diamines were polymerized with four kinds of aromatic tetracarboxylic dianhydrides in DMAc at ambient temperature. The poly(amic acid)s had inherent viscosities in the range of 0.34–0.52 dl/g ( c=0.5 g/dl in DMAc, 30°C). The flexible polyimide film was formed by heating the glass plate on which the polymerization solution was cast. The polyimides had a 10% weight loss temperature range of 550–623°C in N 2 and some among them showed 5% weight loss temperatures over 580°C. The introduction of a double strand (ladder-type) structure into the polymer backbone resulted in highly thermal stability. The T gs of the 2a-based polyimide films were higher than 365°C, although those of the 2b-based polyimides were less than 300°C. The films were insoluble in common organic solvents and exhibited high chemical resistance. The initial moduli of some of these polyimides were excellent, in particular, that of 2b+ODPA was as high as 4.4 GPa.

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 (Tg) of these poly(ether imide)s were recorded between 238–306°C with the help of differential scanning calorimetry (DSC), and the softening temperatures (Ts) 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

Synthesis and properties of new polyimides derived from 1,1-bis[4-(4-aminophenoxy)phenyl]cyclododecane

A new diamine, 1,1-bis[4-(4-aminophenoxy)phenyl] cyclododecane ( BAPCD), bearing flexible ether and bulky pendant cyclododecylidene groups was prepared in three steps from cyclododecanone. The monomer was reacted with six conventional aromatic dianhydrides in N, N-dimethylacetamide (DMAc) to obtain the corresponding new polyimides via the poly(amic acid) precursors and thermal or chemical imidization. The poly(amic acid)s obtained had inherent viscosities ranging from 1.10–1.42 dl g −1. All the poly(amic acid)s could be cast from DMAc solutions and thermally converted into transparent, flexible, and tough polyimide films, except for polymer V a which was derived from pyromellitic dianhydride. X-ray diffractograms of polyimides indicated all polymers were amorphous except the polymer V a . Polyimides derived from 4,4′-sulfonyldiphthalic anhydride and 4,4′-hexafluoroisopropylidenediphathalic anhydride exhibited excellent solubility in various polar solvents. These polymers showed glass transition temperatures between 259°C and 276°C, and decomposition temperatures at initial and 10% mass loss ranging from 430°C to 483°C and from 504°C to 526°C in nitrogen, respectively. The polyimide films, except V a , had a tensile strength in the range 76–112 MPa and a tensile modulus in the range 2.1–3.5 GPa.

Synthesis and properties of poly(ether imide)s based on the bis(ether anhydride)s from hydroquinone and its derivatives

Four bis(ether anhydride)s, 4,4'-(1,4-phenylenedioxy)diphthalic anhydride (IV), 4,4'-(2,5-tolylenedioxy)-diphthalic anhydride (Me-IV), 4,4'-(2-chloro-1,4-phenylenedioxy)diphthalic anhydride (Cl-IV), and 4,4'-(2,5-biphenylenedioxy)diphthalic anhydride (Ph-IV), were prepared in three steps starting from the nucleophilic nitro-displacement reaction of 4-nitrophthalonitrile with the potassium phenoxides of hydroquinone and various substituted hydroquinones such as methylhydroquinone, chlorohydroquinone, and phenylhydroquinone in N,N-dimethylformamide, followed by alkaline hydrolysis and dehydration. Four series of poly(ether imide)s were prepared from bis(ether anhydride)s with various aromatic diamines by a classical two-step procedure. The inherent viscosities of the intermediate poly(amic acid)s were in the range of 0.40-2.63 dL/g. Except for those derived from p-phenylenediamine and benzidine, almost all the poly(amic acid)s could be solution-cast and thermally converted into transparent, flexible, and tough polyimide films. Introduction of the chloro or phenyl substituent leads to a decreased crystallinity and an increased solubility of the polymers. The glass transition temperatures (T g ) of these polyimides were recorded in the range of 204-263°C. In general, the methyl- and chloro-substituted polyimides exhibited relatively higher T g s, whereas the phenyl-substituted ones exhibited slightly lower T g s compared to the corresponding nonsubstituted ones. Thermogravimetric analysis (TG) showed that 10% weight loss temperatures of all the polymers were above 500°C either in nitrogen or in air.

Inverse Chemical Vapor Deposition: A Novel Single Stage Synthesis of Highly Reflective and Conductive Silvered Polymeric Films

Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of the poly(amic acid) formed from 3,3‘,4,4‘-benzophenone tetracarboxylic acid dianhydride and 4,4‘-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction, yielding a reflective and conductive silver surface approaching that of the native metal. The metalized films retain the essential mechanical and thermal properties of the parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy, X-ray photoelectron spectroscopy, and conductivity, reflectivity, thermal, and mechanical measurements.

Preparation and characterization of new polyimides derived from 2,2‐bis[4‐[2‐(4‐aminophenoxy)ethoxy]phenyl]sulfone

A new diamine containing sulfone and oxyethylene unit, 2,2-bis[4-[2-(4-aminophenoxy)ethoxy]phenyl]sulfone (BAEPS), was used as a monomer with various aromatic tetracarboxylic dianhydrides to synthesize polyimides via a conventional two-step procedure. The diamine was prepared through the aromatic nucleophilic substitution of bis[4-(2-hydroxyethoxy)phenyl]sulfone with p-fluoronitrobenzene in the presence of potassium carbonate, followed by catalytic reduction with hydrazine monohydrate/Pd–C. Depending on the dianhydrides used, the poly(amic acid)s obtained had inherent viscosities of 0.90–1.32 dl/g. All the poly(amic acid)s were cast from the N,N-dimethylacetamide solution and thermally converted into transparent, flexible and tough polyimide films. The polyimide films had a tensile strength range of 74–151 MPa and tensile modulus between 1.9 and 3.0 GPa. Almost all the polymers were amorphous except for that derived from dianhydride pyromellitic dianhydride (PMDA). The polyimide derived from 4,4′-hexafluoro-isopropylidenediphathalic anhydride exhibited excellent solubility in various organic solvents. These polyimides had moderate glass transition temperatures of between 185 and 222°C. The PMDA-based polyimide exhibited melting temperature at 413°C. The 10% mass loss temperatures of the polyimides were recorded in the range of 445–468 and 433–452°C in nitrogen and air atmosphere, respectively. Copyright © 1999 John Wiley & Sons, Ltd.

Preparation and characterization of new polyimides derived from 2,2-bis[4-[2-(4-aminophenoxy)ethoxy]phenyl]sulfone

A new diamine containing sulfone and oxyethylene unit, 2,2-bis[4-[2-(4-aminophenoxy)ethoxy]phenyl]sulfone (BAEPS), was used as a monomer with various aromatic tetracarboxylic dianhydrides to synthesize polyimides via a conventional two-step procedure. The diamine was prepared through the aromatic nucleophilic substitution of bis[4-(2-hydroxyethoxy)phenyl]sulfone with p-fluoronitrobenzene in the presence of potassium carbonate, followed by catalytic reduction with hydrazine monohydrate/Pd–C. Depending on the dianhydrides used, the poly(amic acid)s obtained had inherent viscosities of 0.90–1.32 dl/g. All the poly(amic acid)s were cast from the N,N-dimethylacetamide solution and thermally converted into transparent, flexible and tough polyimide films. The polyimide films had a tensile strength range of 74–151 MPa and tensile modulus between 1.9 and 3.0 GPa. Almost all the polymers were amorphous except for that derived from dianhydride pyromellitic dianhydride (PMDA). The polyimide derived from 4,4′-hexafluoro-isopropylidenediphathalic anhydride exhibited excellent solubility in various organic solvents. These polyimides had moderate glass transition temperatures of between 185 and 222°C. The PMDA-based polyimide exhibited melting temperature at 413°C. The 10% mass loss temperatures of the polyimides were recorded in the range of 445–468 and 433–452°C in nitrogen and air atmosphere, respectively. Copyright © 1999 John Wiley & Sons, Ltd.

Synthesis and characterization of new soluble polyimides derived from 2,2-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]propane

A diamine monomer containing isopropylidene and methyl substituted arylene ether, 2,2-bis[3,5-dimethyl-4-(4-aminophenoxy)phenyl]propane (TBAPP), was prepared in two steps. The monomer was reacted with six different aromatic tetracarboxylic dianhydrides in N.N-dimethylacetamide (DMAc) to obtain the corresponding new polyimides via the poly(amic acid) precursors and thermal or chemical imidization. The poly(amic acid)s obtained had inherent viscosities ranging from 1.38-2.10 dL . g 1 . All the poly-(amic acid)s could be cast from DMAc solutions and thermally converted into transparent, flexible, and tough polyimide films. The polyimide films had a tensile strength in the range from 52-95 MPa, an elongation at break within a range of 4-8%, and a tensile modulus in the range from 1.60-2.09 GPa. All polyimides were amorphous. The polyimides derived from diamine TBAPP had excellent solubility in various solvents except for those derived from rigid dianhydrides such as pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride. These polyimides showed glass transition temperatures between 249-293 C and decomposition temperature at 10% mass loss temperatures ranging from 460-485°C in nitrogen.

Eddy-current testing by flexible microloop magnetic sensor array

A flexible microloop magnetic sensor array has been developed for nondestructive evaluation in nuclear power plants and its fundamental characteristics have been investigated. A flexible micro-eddy current testing (micro-ECT) probe consists of a pancake-type exciting coil of the diameter of 3.2 /spl mu/m and a flexible microloop magnetic sensor array with an area of 14/spl times/14 mm/sup 2/ and a thickness of 125 /spl mu/m. The array has 16 microloop sensors made of copper formed on a flexible polyimide film by sophisticated photolithography. Each coil has 40 turns (8 /spl mu/m line and 8 /spl mu/m space) within an area of 2/spl times/2 mm/sup 2/. The flexible sensor array enables the micro-ECT probe to be applied to an arbitrary geometric configuration. The purpose of this work is to detect and reconstruct flaws in conductive tubing of a steam generator in a pressurized nuclear power reactor by using the flexible micro-ECT probe with higher spatial resolution than that of a conventional ECT probe. The spatial resolution of flaw detection was 3 mm and the detectability of an outer 20% flaw made by electric discharge machining was confirmed. The reconstruction of circumferential and axial flaws using the electromotive force and phase measured with the sensor array is described. Three-dimensional eddy current and magnetic field analysis was also performed for comparison with measured data. Finally, a design study of a practical and robust micro-ECT for a realistic tube configuration with respect to detectability was carried out.

Synthesis and properties of aromatic polyimides based on ether-sulfone-diamines

Two diamine monomers, 4,4′-[sulfonylbis(1,4-phenyleneoxy)]dianiline (IIIa) and 4,4′-[sulfonylbis(2,6-dimethyl-l,4-phenyleneoxy)]dianiline (IIIb), were prepared by an aromatic nucleophilic substitution of 4,4′-sulfonyldiphenol (Ia) and 4,4′-sulfonylbis(2,6-dimethylphenol) (Ib) with p-chloronitrobenzene in the presence of potassium carbonate, followed by hydrazine catalytic reduction of the intermediate dinitro compounds. The diamines IIIa and IIIb were used as monomers with various aromatic tetracarboxylic dianhydrides (IVa–f) to synthesize polyimides. The polymerization was conducted in two steps via the formation of a poly(amic acid) precursor followed by thermal cyclodehydration. The poly(amic acid)s had inherent viscosities above 0.87 and up to 2.56 dL/g. Most poly(amic acid)s could be coated and thermodehydrated into flexible and transparent polyimide films. The polyimides derived from the dianhydrides containing-O-and-SO2-or-C(CF3)2-bridging groups between the phthalic anhydride units were soluble in some organic solvents such as N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF). The glass transition temperatures (Tg) of the polyimides were in the range from 254 to 300 °C. The methyl-substituted polyimides exhibited slightly higher solubility and higher Tg compared to the corresponding unsubstituted polyimides. Thermogravimetric analysis (TG) showed that the polyimides containing methyl substitutents started to lose weight around 450 °C and the unsubstituted ones started to lose weight around 550 °C.

Synthesis and Properties of 1,4-Bis(4-aminophenoxy)naphthalene and Its Polyimides

A new diamine 1,4-bis(4-aminophenoxy)naphthalene (1,4-BAPON) was prepared through the nucleophilic displacement of 1,4-dihydroxynaphthalene with p-fluoronitrobenzene in the presence of K2CO3 in N,N-dimethylacetamide (DMAc), followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of novel aromatic polyimides containing 1,4-bis(aminophenoxy)naphthalene units was synthesized from 1,4-BAPON and various aromatic tetracarboxylic dianhydrides by the conventional two-stage procedure that included ring-opening polyaddition in a polar solvent such as DMAc, to give poly(amic acid)s, followed by thermal cyclodehydration to polyimides. Depending on the dianhydrides used, the poly(amic acid)s obtained had inherent viscosities of 0.81–1.33 dL g−1. All the poly(amic acid)s could be solution cast and thermally converted into transparent, flexible, and tough polyimide films. These polyimides had glass transition temperatures between 247–281°C. Thermogravimetric analyses established that these polymers were fairly stable up to 500°C, and 10% weight loss temperatures were recorded in the range of 521–581°C in nitrogen and 517–575°C in air atmosphere.

Synthesis and properties of polyimides derived from 3,3′,5,5′-tetramethyl-bis[4-(4-aminophenoxy)phenyl]sulfone

The novel diamine containing methyl-substituted arylene sulfone ether, 3,3′5,5′-tetramethylbis[4-(4-aminophenoxy)phenyl]sulfone (TBAPS), was used as a monomer with various aromatic tetracarboxylic dianhydrides to synthesize polyimides via a conventional two-stage procedure that included ring-opening polyaddition in a polar solvent such as N,N-dimethylacetamide (DMAc) to give poly(amic acid)s, followed by cyclodehydration to polyimides. The diamine was prepared through the nucleophilic displacement of bis(4-hydroxy-3,5-dimethylphenyl)sulfone with p-chloronitrobenzene in the presence of K 2 CO 3, followed by catalytic reduction. Depending on the dianhydrides used, the poly(amic acid)s obtained had inherent viscosities of 0.80−1.72 dL g −1. All the poly(amic acid)s could be cast from DMAc solutions and thermally converted into transparent, flexible and tough polyimide films. The polyimide films had a high tensile strength range 81–118 MPa, an elongation range at break 5–9% and a tensile modulus range 1.78–2.49 GPa. The polyimide derived from 4,4′-hexafluoroisopropylidenebis-phathalic anhydride had better solubility than the other polyimides. These polyimides had glass transition temperatures between 291–339 °C and 10% mass loss temperatures were recorded in the range 550–591 °C in nitrogen and 556–588 °C in air atmosphere.

Preparation and properties of polymides, polyamides and poly(amide‐imide)s based on a spirobichroman dietheramine

AbstractA novel diamine, 7,7′‐bis(4‐aminophenoxy)‐4,4,4′,4′‐tetramethyl‐2,2′‐spirobichroman (3), was synthesized and used as a monomer with various aromatic tetracarboxylic dianhydrides, dicarboxylic acids and imide ring‐containing dicarboxylic acids, to synthesize polymides, polyamides and poly(amide‐imide)s, respectively. The polyimides 5a–f were prepared from diamine 3 and various aromatic tetracarboxylic dianhydrides via a conventional two‐stage procedure. The intermediate poly(amic acid)s had inherent viscosities of 0,84 – 1,65 dL/g and could be thermally converted into transparent, flexible, and tough polyimide films. Some polyimides were readily soluble in polar solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidone (NMP). The glass transition temperatures (Tg) of these polyimides were in the range of 155–280°C, and 10% weight loss temperatures were above 450°C in air or nitrogen. Furthermore, a series of polyamides and poly(amide‐imide)s having inherent viscosity between 0,40–1,69 dL/g were prepared by direct polycondensation of the diamine 3 with various aromatic dicarboxylic acids and imide ring‐containing dicarboxylic acids. All the polyamides and poly(amide‐imide)s were soluble in a variety of organic solvents and could be solution‐cast into flexible and tough films. They had Tg values in the 150–237°C range and showed no significant weight loss below 400°C in air and nitrogen atmosphere.

Synthesis and properties of polyimides, polyamides and poly(amide-imide)s from ether diamine having the spirobichroman structure

A novel spirobichroman unit containing dietheramine, 6,6′-bis(4-aminophenoxy)-4,4,4′,4′,7,7′-hexamethyl-2,2′-spirobichroman (3), was prepared by the nucleophilic substitution of 6,6′-dihydroxy-4,4,4′,4′,7,7′-hexamethyl-2,2′-spirobichroman with p-chloronitrobenzene in the presence of K2CO3 followed by hydrazine catalytic reduction of the intermediate dinitro compound. A series of polyimides were synthesized from diamine 3 and various aromatic dianhydrides by a conventional two-stage procedure through the formation of poly(amic-acid)s followed by thermal imidization. The intermediate poly(amic-acid)s had inherent viscosities of 1.00–2.78 dL/g. All the poly-(amic-acid)s could be thermally cyclodehydrated into flexible and tough polyimide films, and some polyimides were soluble in polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF). These polyimides had glass transition temperatures (Tg) in the range of 236–256°C, and 10% weight loss occurred up to 450°C. Furthermore, a series of polyamides and poly(amide-imide)s with inherent viscosities of 0.71–2.29 dL/g were prepared by direct polycondensation of the diamine 3 with various aromatic dicarboxylic acids and imide ring-containing dicarboxylic acids by means of triphenyl phosphite and pyridine. All the polyamides and poly(amide-imide)s were readily soluble in polar solvents such as DMAc, and tough and flexible films could be cast from their DMAc solutions. These polymers had glass transition temperatures in the range of 137–228°C and 10% weight loss temperatures in the range of 419–443°C in air and 404–436°C in nitrogen, respectively. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1487–1497, 1997

Soluble aromatic polyimides based on 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane: Synthesis and properties

Aromatic polyimides were synthesized from 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6F-OH diamine) and different aromatic dianhydrides by a one-step hightemperature polycondensation, or by a two-step procedure using either thermal or chemical imidization of poly(amic acids), PAA. The obtained polyimides were compared in terms of their chemical structure, molecular weight, mechanical and thermal properties. The reaction of 6F-OH diamine with different aromatic dianhydrides in amide solvents at room temperature resulted in the formation of PAA with moderate molecular weight (ηinh ⩽ 0.7 g/dL). The thermal imidization of these PAAs led to brittle hydroxy polyimides (PI-6F-OH). In contrast, chemical imidization of similar PAAs in acetic anhydride and pyridine brought about flexible self-supporting polyimide films. The FTIR analysis indicated that the latter process was accompanied by an esterification of the OH groups in the diamine moieties, resulting in the formation of the polymers with side acetate groups (PI-6F-Ac). The high molecular weight hydroxy polyimides, suitable for preparation of films with good tensile properties, were synthesized by a one-step high-temperature polycondensation in phenolic solvents. All obtained polyimides were well soluble in common organic solvents. The highest solubility was observed for PI-6F-Ac. It was found by means of FTIR and TGA that the polyimides with the R group (R = OH or acetate) in orto position to the nitrogen atom in the diamine moiety underwent a rearrangement to benzoxazoles above 300°C. The starting temperature and conversion of this rearrangement reaction were controlled by the type of R group. The imide-to-benzoxazole rearrangement shifted to lower temperatures, and higher conversion was encountered for the polyimides with side acetate group, PI-6F-Ac, obtained by chemical imidization. © 1996 John Wiley & Sons, Inc.

Synthesis and properties of polyimides derived from 1,6‐bis(4‐aminophenoxy)naphthalene and aromatic tetracarboxylic dianhydrides

Abstract1,6‐Bis(4‐aminophenoxy)naphthalene (I) was used as a monomer with various aromatic tetracarboxylic dianhydrides to synthesize polyimides via a conventional two‐stage procedure that included ring‐opening polyaddition in a polar solvent such as N,N‐dimethylacetamide (DMAc) to give poly(amic acid)s, followed by thermal cyclodehydration to polyimides. The diamine (I) was prepared through the nucleophilic displacement of 1,6‐dihydroxynaphthal‐ene with p‐chloronitrobenzene in the presence of K2CO3, followed by catalytic reduction. Depending on the dianhydrides used, the poly(amic acid)s obtained had inherent viscosities of 0.73–2.31 dL/g. All the poly(amic acid)s could be solution cast and thermally converted into transparent, flexible, and tough polyimide films. The polyimide films had a tensile modulus range of 1.53–1.84 GPa, a tensile strength range of 95–126 MPa, and an elongation range at break of 9–16%. The polyimide derived from 4,4′‐sulfonyldiphthalic anhydride (SDPA) had a better solubility than the other polyimides. These polyimides had glass transition temperatures between 248–286°C (DSC). Thermogravimetric analyses established that these polymers were fairly stable up to 500°C, and the 10% weight loss temperatures were recorded in the range of 549–595°C in nitrogen and 539–590°C in air atmosphere. © 1995 John Wiley & Sons, Inc.

Synthesis and characterization of perfluoroalkyl-substituted aromatic polyimides.

Novel fluorine-containing aromatic polyimides having perfluorooctyl group were synthesized through the conventional two-step method; the ring-opening polyaddition of N, N-bis(4-aminophenyl)-4-perfluorooctylaniline to aromatic tetracarboxylic dianhydrides in a polar aprotic solvent at room temperature giving polyamic acids with inherent viscosities of 0.4-0.6dL/g, which were subsequently subjected to thermal cyclodehydration affording yellow to dark red, transparent, and flexible polyimide films. All the polyimides were insoluble in organic solvents. The polymer films had moderate tensile strength of 50-70MPa, high contact angles of water and methylene iodide of 98° and 69°, respectively, which indicating low surface free energy. The glass transition temperatures of polymers were in the range of 234-247°C and the 10% weight loss temperatures were around 500°C in air.