Hexafluoropropane Dianhydride Research Articles

P3G184 - New molecular bioassay based on cell differentiation in vitro for the estimation of the teratogenic potency of valproic acid derivatives

The gas permeation behavior of 2,2′-bis(3,4′dicarboxyphenyl) hexafluoropropane dianhydride(6FDA)-2,4,6-trimethyl-1,3-phenylenediamine (TMPDA)/4,4′-methylene bis(2-chloroaniline) (MOCA) copolyimides was investigated by systematically varying the diamine ratios. All the copolyimides were soluble in most of the common solvents. The gas permeabilities and diffusion coefficients decreased with increasing MOCA content; however, the permselectivity of gas pairs such as H2/N2, O2/N2, CO2/CH4 was enhanced with the incorporation of MOCA moiety. Moreover, all of the copolyimides studied in this work exhibited performance near, lying on or above the existing upper bound trade-off line between permselectivity and permeability.

Synthesis and properties of novel photosensitive polyimides containing chalcone moiety in the main chain

Two chalcone-derivative isomers, 4,4′-diaminochalcone (4DAC) and 3,3′-diaminochalcone (3DAC), were synthesized and used as monomers together with tetracarboxylic dianhydrides to prepare novel photosensitive polyimides that contain a chalcone moiety in the main chain. The polyimides were characterized and their photochemical behavior was investigated as thin films and in solutions with the aid of ultraviolet and infrared spectroscopy. Compared with 4DAC-based polyimides, the 3DAC-based polyimides exhibited lower glass transition temperatures and higher photocrosslinking rates of the carbon–carbon double bond as well as higher photosensitivities obtained from the exposure characteristic curves, suggesting that an increase in the photoreactivity of the 3DAC-based polyimides might arise from the improved flexibility of their backbones. The polyimide from 3DAC and 6FDA (2,2-bis[3,4-dicarboxypheny]hexa-fluoropropane dianhydride) showed a photosensitivity of 33 mJ/cm2 with a contrast of 1.5 upon light irradiation using a Xenon lamp. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 685–693, 1998

Synthesis and properties of polyimides from thianthrene-2,3,7,8-tetracarboxylic dianhydride-5,5,10,10-tetraoxide

Thianthrene - 2,3,7,8 - tetracarboxylic dianhydride - 5,5,10,10 - tetraoxide (TADATO), a dianhydride having two sulfonyls between two phenyl rings, was synthesized and polymerized with several diamines by a two-step method. Tough polyimide membranes were obtained with flexible diamines but not with rigid diamines. Most of TADATO-based polyimides are soluble in polar solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. IR study confirmed that almost complete imidization of TADATO-based poly(amic acid) membranes could be achieved by thermal treatment at 100, 200, and 300°C for each 1 h. In a series of polyimides based on 4,4′-oxydianiline, the polyimide from TADATO showed higher gas permeability coefficient of CO2 and higher selectivities of CO2/N2 and CO2/CH4 than those of polyimides from pyromellitic dianhydride and 3,3′,4,4′-biphenyltetracarboxylic dianhydride, and was comparable to that from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 485–494, 1998

Thermal behaviour of ethynyl and ethenyl terminated imide resins

A series of ethynyl and ethenyl end-capped imide resins were synthesised by the reaction of 9,9-bis(4-aminophenyl) fluorene (BAF) with pyromellitic dianhydride (PMDA)3/3′, 4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxy phenyl) hexafluoropropane dianhydride (6F) and 3-ethynyl aniline/maleic anhydride. Structural characterisation was done by infra red and elemental analysis. Thermal characterisation was done by differential scanning calorimetry and thermogravimetric analysis. The decomposition temperatures of cured resins were above 200°C in nitrogen atmosphere. Char yield at 800°C ranged from 59–65.5%.

Investigation of the Solution Behavior of Organosoluble Aromatic Polyimides

Two high-molecular-weight organosoluble aromatic polyimides having the same diamine, 2,2′-(trifluoromethyl)-4,4′-diaminobiphenyl diamine (PFMB), but different dianhydrides, 2,2′-bis(trifluoromethyl)-4,4′,5,5′-biphenyltetracarboxylic dianhydride (HFBPDA) and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), were prepared via one-step polycondensation reactions. Molecular weight fractionation of these two polymers was carried out and the polyimide fractions possess successively lower weight-average molecular weights. Intrinsic viscosity data from both sets of polyimide fractions gave the Mark-Houwink-Sakurada constants of these two polyimides, which reflect differing chain rigidity in tetrahydrofuran (THF) solutions. The MHS relations are [η] = 5.24 × 10−4 M0.65 and [η] = 3.77 × 10−5 M0.97 for 6FDA-PFMB and HFBPDA-PFMB, respectively. The physical meanings of these constants are discussed using the intrinsic viscosity data of these two polyimides in varying solvents. The persistence lengths are calculated based on the viscosity and molecular weight results using Bohdanecky' s approach and they were calculated to be 6.6 and 2.0 nm for HFBPDA-PFMB and 6FDA-PFMB, respectively. The experimental results indicate that the fully aromatic HFPBDA-PFMB is more rigid in THF solutions compared with 6FDA-PFMB. However, both of these polyimides are far from possessing true rigid-rod character. Plots of the weight-average molecular weight against the elution volume depict the differences in chain stiffness, and hence in hydrodynamic volume, between samples. Examination of the hydrodynamic volume of these polymers provides evidence that they both subscribe rather well to hydrodynamic theory at high molecular weights but that the stiffer HFBPDA-PFMB shows deviation at lower values.

Laser light scattering studies of soluble high performance fluorine‐containing polyimides, 1. Polyimide synthesized from 2,2′‐bis(3,4‐dicarboxyphenyl)‐hexafluoropropane dianhydride and 2,2′‐(trifluoromethyl)‐4,4′‐biphenyldiamine

AbstractFive fractions of a polyimide synthesized from 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′‐(trifluoromethyl)‐4,4′‐biphenyldiamine (PFMB) (6FDA/PFMB) in tetrahydrofuran (THF) at 30°C were investigated by a combination of static and dynamic laser light scattering (LLS). The relations of 〈Rh〉 (nm) = 2.38 x 10−2 Mw0.560 and A2 (mol · cm−3 · g−2) = 2.1 × 10−1 Mw−0.43 were established, where Mw, 〈Rh〉 and A2 are weight‐average molecular weight, average hydrodynamic radius and second virial coefficient, respectively. A combination of Mw and the translational diffusion coefficient distribution G(D) leads to a relation of D(cm2/s) = 2.41 × 10−4 M0.564. With this relation, we successfully convert each G(D) into a corresponding molecular weight distribution (MWD). On the basis of the Benoit‐Doty theory, we found that the persistence length and the Flory characteristic ratio C∞ of the 6FDA‐PFMB chain are ∼3.3 nm and ∼40, respectively, indicating that the 6FDA‐PFMB chain is more extended than typical random‐coil chains. On the other hand, the ratio of the radius of gyration to the hydrodynamic radius, i.e., 〈Rg〉/〈Rh〉 ∼ 1.8, together with the values of the exponents (∼0.56) indicate that the 6FDA‐PFMB chain has a coil chain conformation. Therefore, the 6FDA‐PFMB chain has an extended coil conformation in THF at 30°C.

Aromatic Poly(ether imide)s Bearing Isopropylidene or Hexafluoroisopropylidene Links in the Main Chain

Two bis(ether anhydride) monomers, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (4) and 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride (4-F), were synthesized from readily available compounds in three steps in high yields. Two series of poly(ether imide)s 7a-g and 7a-g-F based on dianhydrides 4 and 4-F, respectively, were synthesized by a conventional two-step procedure that included a ring-opening polyaddition to give poly(amic acid)s, followed by cyclodehydration to polyimides. The intermediate poly(ether amic acid)s and the poly(ether imide)s had inherent viscosities in the range of 0.29–1.09 dL g−1 and 0.21–0.98 dL g−1, respectively. Except for the poly(ether imide)s derived from benzidine, the others afforded flexible and tough films. Most of the obtained poly(ether imide)s are organic-soluble. The glass transition temperatures (Tg) of these polymers ranged from 204 to 259°C. Degradation temperatures for 10% weight loss all occurred above 505°C in nitrogen and above 501°C in air. Fluorine-containing poly(ether imide)s showed higher solubility, Tgs and degradation temperatures in nitrogen, as compared to their respective nonfluorine-containing counterparts.

Gas transport properties of soluble poly(phenylene sulfone imide)s

Gas transport of helium, hydrogen, carbon dioxide, oxygen, argon, nitrogen, and methane in three soluble poly(phenylene sulfone imide)s based on 2,2-bis(3,4- decarboxyphenyl) hexafluoropropane dianhydride (6FDA) has been investigated. The effects of increasing length of well-defined oligo(phenylene sulfone) units on the gas permeabilities and diffusivities were determined and correlated with chain packing of the polymers. Activation energies of diffusion and permeation were calculated from temperature-dependent time-lag measurements. The influences of the central group in the diamine moiety of 6FDA-based polyimides on physical and gas transport properties are discussed. The incorporation of a long oligo(phenylene sulfone) segment in the polymer backbone decreases gas permeability and permselectivity simultaneously. The decreases in permeability coefficients can be mainly related to decreases in diffusion coefficients. Changing the central group of diamine moiety from {S{ to {SO2{ leads to a 45-50% decrease in CO2 and O2 permeabilities without appreciable increase in the selectivities. This is considered to be due to the formation of charge transfer complexes. q 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1855-1868, 1997

Ternary fluoro-containing polyimide blends and fluoro-containing polyimide/polyester blends

Two ternary miscible fluoro-polyimide blends have been identified. They are 6FDA-3,3′-6F-diamine/6FDA-4,4′- F - diamine/BTDA - 4,4′ - 6FDA blend and 6FDA - 3,3′ - 6F - diamine/6FDA - 4,4′ - 6F - diamine/ODPA - PMDA - 4,4′-6F-diamine blend (6FDA is 2,2′-bis(3,4′-dicarboxy- phenyl)hexafluoro propane dianhydride, 6F-diamine is 2,2′-bis(3-aminophenyl) hexafluoro propane). Their miscibility probably arises from the fact that their diamine parts have hexafluoro isopropylidene groups, their dianhydride parts have similar bond angle, space, rigidity and length. Several 6FDA-polyimides and PCTG 5445 (glycol-modified polycyclohexanedimethanolterephthalate) form- ing miscible blends have also been discovered. These surprising results suggest that hexafluoro-isopropylidene-group containing polyimides are quite intermolecular active and the 1,4-cyclohexane dimethanol component in PCTG 5445 may also offer unique miscibility capability. © 1997 John Wiley & Sons, Ltd.

Ternary fluoro‐containing polyimide blends and fluoro‐containing polyimide/polyester blends

Two ternary miscible fluoro-polyimide blends have been identified. They are 6FDA-3,3′-6F-diamine/6FDA-4,4′- F - diamine/BTDA - 4,4′ - 6FDA blend and 6FDA - 3,3′ - 6F - diamine/6FDA - 4,4′ - 6F - diamine/ODPA - PMDA - 4,4′-6F-diamine blend (6FDA is 2,2′-bis(3,4′-dicarboxy- phenyl)hexafluoro propane dianhydride, 6F-diamine is 2,2′-bis(3-aminophenyl) hexafluoro propane). Their miscibility probably arises from the fact that their diamine parts have hexafluoro isopropylidene groups, their dianhydride parts have similar bond angle, space, rigidity and length. Several 6FDA-polyimides and PCTG 5445 (glycol-modified polycyclohexanedimethanolterephthalate) form- ing miscible blends have also been discovered. These surprising results suggest that hexafluoro-isopropylidene-group containing polyimides are quite intermolecular active and the 1,4-cyclohexane dimethanol component in PCTG 5445 may also offer unique miscibility capability. © 1997 John Wiley & Sons, Ltd.

The effects of spinning conditions on asymmetric 6FDA/6FDAM polyimide hollow fibers for air separation

We have found that the chemistries of inner and external coagulants, gelation bath temperature, and air gap distance have profound effects on 6FDA-polyimde hollow-fiber morphology and performance. This 6FDA-polyimide is made of 50 mol % 2,2′-bis(3,4′-dicarboxyphenyl) hexafluoro propane dianhydride (6FDA) and 50 mol % 2,2′-bis(3-aminophenyl) hexafluoro propane (4,4′ 6F-diamine) (6FDAM). An increase in air gap distance tends to induce three-dimensional open-cell pore formation. Raising bath temperature has a similar effect. Multilayer finger-void structure can be completely eliminated if one properly chooses a bore-fluid flow rate and a gelation bath temperature. Experimental data demonstrate that the location of the dense layer can be shifted from the inner skin to the outer skin based on the chemistry (solubility parameter) of coagulants. The location of finger voids is also dependent on the chemistry of coagulants, and the dense layer location may shift from the inner surface to the external surface or appear in both surfaces dependent on the differences in solubility and coagulation rate. A defect-free 6FDA/6FDAM polyimide fiber with a selectivity of 4.73 and a permeance of 38.1 GPU is produced. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1555–1569, 1997

Thermally stable imide oligomers from acridine yellow

The synthesis and characterization of three new imide oligomers from acridine yellow, using pyromellitic dianhydride (PMDA), 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) and 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), is reported in this paper. Due to the poor reactivity of acridine yellow, a two-step synthesis technique at lower temperature produced little or no product. The one-step, elevated temperature, solution imidization technique was deemed to be more efficient and was used to synthesize polyimides. Optimized reaction conditions were determined for all these polymers. Intrinsic viscosity values of poly(acridine yellow- co-PMDA) (AYPMDA), AYBTDA and AY6FDA polyimides were 0.11 in N-methyl-2-pyrrolidinone (NMP) and 0.10 and 0.13 dimethylformamide (DMF), respectively. The newly synthesized imide oligomers were thermally stable up to 400°C in a nitrogen atmosphere. AYBTDA and AY6FDA polyimides were soluble in DMF and dimethyl sulfoxide. AYPMDA polyimide was soluble in NMP.

Bis(3-aminophenyl)methyl phosphine oxide-based (methyl) nadicimide resins

Ten nadicimide/methyl nadicimide end-capped oligomeric resins were prepared by reacting endo-5-norbornene-2,3-dicarboxylic acid anhydride (methyl nadic anhydride), pyromellitic dianhydride (PMDA)/3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6F), and bis(3-aminophenyl) methyl phospine oxide (BAP) in glacial acetic acid/ acetone. Structural characterization of the resins was done by elemental analysis, IR, and 1 H-NMR. Multistep decomposition was observed in the TG scan of uncured resins in a nitrogen atmosphere. Residual weight at 800°C depended on the structure and ranged between 25 and 51%. Isothermal curing of the resins was done at 300°C for 1 h in an air atmosphere. These cured resins were stable to 350 ± 30°C and decomposed in a single step above this temperature. The char yield of the resins increased on curing and was in the range 34-70%.

Synthesis and Photodegradation of Positive Working Polyimides Derived from 2-Nitro-p-xylyleneoxyamine

Two kind of diamines, 2-nitro-p-xylyleneoxyamine (5a) and p-xylyleneoxyamine (5b) were synthesized and used as monomers together with various tetracarboxylic dianhydrides to prepare the main-chain photodegradative polyimides which exhibited a positive working image upon light irradiation. The photosensitivities of the polyimides and the viscosities of their precursors on irradiation indicated that the nitro group substituted at the ortho position of the benzene ring of the diamine moiety improved the photolytic decomposability of polymers by at least 1−2 orders of magnitude compared with the hydrogen at the same position. Furthermore, much higher sensitivity was attained by using polyimide films such as 6FDA−5a (polycondensate of 2,2-bis(3,4-dicarboxypheny)hexafluoropropane dianhydride and 5a) and BHTCA−5a (polycondensate of bicyclo[2.2.1]heptane-2-exo,3-exo,5-exo,6-exo-tetracarboxylic 2,3:5,6-dianhydride and 5a), which contained either a bulky trifluoromethyl (−CF3) substituent or a polyalicyclic structure along the polymer backbone. The higher photosensitivities of 6FDA−5a and BHTCA−5a (95 and 85 mJ/cm2, respectively) might be explained by the greater solubilities of the segments decomposed from these polyimides in development solvent. Therefore, a discussion on the photochemical behavior of polyimides studied was presented.

Gas transport properties of poly(phenylene thioether imide)s

Gas transport of carbon dioxide, oxygen, nitrogen and methane gases in a series of poly(phenylene thioether imide)s based on 2,2-bis(3,4-decarboxyphenyl) hexafluoropropane dianhydride and diamine-terminated oligo(phenylene thioether)s has been investigated. The effects of the oligo(phenylene thioether) length on the gas permeabilities and diffusivities were determined and correlated with chain packing of the polymers. The incorporation of a long oligo(phenylene thioether) segment in the polymer backbone decreases gas permeability and permselectivity simultaneously. The decreases in permeability coefficients can be related to decreases in both the diffusion coefficients and the solubility coefficients of all the gases. Finally, the physical and gas transport properties are simply compared between poly(phenylene thioether imide)s and poly(phenylene thioether).

Gas transport properties of highly fluorinated polyamideimides

Gas transport properties of a series highly fluorinated polyamideimides based on 2,2-bis(3,4-decarboxyphenyl)hexafluoropropane dianhydride and N,N-bis(amino-phenyl)-perfluoroalkane-α,ω-dicarboxamide diamines have been measured as a function of upstream pressure and temperature. The results show that the permeability coefficients P for the penetrant gases in any of the four polyamideimides decrease in the gas order: P(CO 2) > P(O 2) > P(N 2) > P(CH 4), while the permeabilities for a given gas in these polymers increase with the increase of oligo(tetrafluoroethene) segment length. The effects of the substitution pattern of the phenyl ring and the length of the oligo(tetrafluoroethene) segments in the diamine moieties on gas permeabilities, diffusivities and solubilities are discussed. It seems that, comparing with the effect of the flexible oligo(tetrafluoroethene) segment, the substitution patterns of phenyl group in the diamine moieties have no notable effect of the diffusivities in the polyamideimides as the length of the oligo(tetrafluoroethene) segment increasing from 8 to 12 carbons. The activation energies of permeation and diffusion were obtained for the gas/polymer pairs studied and correlated with the size of penetrant gas.

A Photoreactive Polyimide with Main-Chain Chalcone Moiety.

A fully imidized photosensitive polyimide with a chalcone moiety in the main chain was developed. It was derived from 4, 4′-diaminochalcone and 6FDA (2, 2-bis(3, 4-dicarboxyphenyl) hexafluoropropane dianhydride). The polyimide was characterized and its photochemical behavior was investigated in the film state and in the solution using UV and IR spectroscopy. The polyimide exhibited a good thermal stability (5% weight loss temperature at 485°C) and a high glass transition temperature of 267°C as well as an excellent solubility even in low polar solvents such as 1, 4-dioxane and chloroform. This negative working polyimide also possessed a photosensitivity of 130mJ/cm2 with a high contrast of 3.4 when exposed to light from a Xenon lamp.

Gas permeability and selectivity through asymmetric polyimide membranes

Permeability and selectivity of CO 2 , O 2 , N 2 , and CH 4 were determined for the asymmetric membrane of aromatic polyimide derived from 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 3,3'-diaminodiphenylsulfone (m-DDS) at 35°C and at pressure up to 76 cmHg. The average apparent skin layer thickness of all asymmetric membranes measured was 2.6 μm. The selectivities for (O 2 /N 2 ) and (CO 2 /CH 4 ) in the membranes were 11.5 at O 2 permeance of 3.2 X 10 -7 and 153 at CO 2 of 6.3 X 10 -7 [cm 3 (STP)/cm 2 s cmHg], respectively, without the necessity of an additional coating process. The average gas selectivities of the asymmetric membranes were much larger than those determined for the dense membranes. The effect of the microstructure of polyimide on the gas selectivity is discussed.

Gas transport properties in thermally cured aromatic polyimide membranes

Aromatic polyimide derived from 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 3,3′-diaminodiphenylsulfone (m-DDS) has been synthesized to facilitate the study of relationships between the polymer structure and the gas transport properties (permeability and selectivity). The gas permeability and selectivity of CO 2, O 2, N 2, and CH 4 for the 6FDA-m-DDS membranes cured at 150, 200, and 250°C have been determined at 35°C and at pressures up to 760 cmHg. The packing density and the fluorescence intensity of the 6FDA-m-DDS polyimide increased sharply with the increasing curing temperature. We propose that this behavior is associated with an increase in intermolecular and/or intramolecular interactions by a charge transfer complex formed in 6FDA-m-DDS containing an alternating sequence of electron donor and electron aceptor molecules. The effect of the microstructure of the thermally cured 6FDA-m-DDS membranes on their gas transport properties is discussed.

Gas permeation properties of new type asymmetric membranes

We have developed a new type of asymmetric membranes having a homogeneous hyperthin skin layer, which was used as a polyimide synthesized by 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2-bis(4-amino phenyl) hexafluoro-propane (BAAF). The skin layer thicknesses of the 6FDA-BAAF polyimide asymmetric membranes were 40–60 nm, and the porosity was 10-6% when a defect size was assumed as 5 nm. The permselectivity of 6FDA-BAAF polyimide asymmetric membranes after silicone coating had α of 40 for CO2/CH4 and a flux of 1.0 [Nm3/m2-h-atm] (=3.7 × 10−4 [cm3(STP)/cm2 s cmHg]) for CO2, α of 4.3 for O2/N2 and a flux of 2.0 × 10−1 [Nm3/m2/h/atm] (=7.1 × 10−5 [cm3(STP)/cm2s cmHg]) for O2. These values were constant for large-scale manufacturing. © 1996 John Wiley & Sons, Inc.