Hexafluoroisopropylidene Groups Research Articles

Synthesis and study of new fluorinated poly(imide-amide)s

New fluorinated poly(imide-amide)s have been synthesized by solution polycondensation of various aromatic diamines containing a naphthalene unit with diacid chlorides having both imide and hexafluoroisopropylidene (6F) groups. These polymers are soluble in polar aprotic solvents, such as N-methylpyrrolidone (NMP) or N,N-dimethylformamide (DMF), and can be cast into flexible thin films from solutions. They show high thermooxidative stability with decomposition temperatures being above 425°C and glass transition temperatures being in the range of 235–305°C. The polymer films exhibit a low dielectric constant and tough mechanical properties.

COMPARED PROPERTIES OF FLUORINATED HETEROCYCLIC COPOLYIMIDES

Various new fluorinated heterocyclic copolyimides have been synthesized by a polycondensation reaction of a diacid chloride containing imide, hexafluoroisopropylidene and methylene groups with aromatic or heteroaromatic diamines containing preformed phenylquinoxaline or 1,3,4-oxadiazole rings. Other fluorinated heterocyclic copolyimides have been prepared by a polycondensation reaction of the same diacid chloride with aromatic dihydrazides, bis(o-hydroxy-amine)s or a bis(o-carboxy-amine), resulting in intermediate polyhydrazides, poly(o-hydroxy-amide)s or poly(o-carboxy-amide), respectively, which were futher cyclodehydrated to the corresponding polyoxadia zole-imide, polybenzoxazole-imide or polybenzoxazinone-imide structure. These polymers showed good solubility in polar amidic solvents, such as N-methylpyrrolidinone (NMP) and dimethylformamide (DMF), and even in less polar liquids, like tetrahydrofurane or pyridine, except for those compounds containing benzoxazole rings which were less soluble, only on heating in NMP or DMF. The weight average molecular weight measured for tetrahydrofurane-fully-soluble polymers are in the range of 12800–26700 and the polydispersity is in the range of 2–5. All these polymers exhibited good thermal stability, with decomposition temperature being above 350°C, although somewhat lower than that of related polymers prepared by using fully aromatic diacid chlorides instead of the present ones containing methylene units. The glass transition temperature is in the range of 200–300°C. The dielectric constant measured for polymer films is in the range of 3.3–3.7. Tensile strength is in the range of 35–70 MPa, elongation to break between 30–40% and tensile modulus in the range of 170–330 MPa. A study of the relation between conformational parameters and properties of some of these polymers has been carried out by using the Monte Carlo method with an allowance for hindered rotation, and the values were compared with the experimental data and discussed in relation with the rigidity of the chains. The present polymers are potential candidates for use as high performance materials.

Thin films from new poly(imide-ether-amide)s containing hexafluoroisopropylidene groups

A series of fluorinated poly(imide-ether-amide)s has been synthesized by solution polycondensation of aromatic diamines containing two ether bridges between phenylene rings with diacid chlorides having both imide and hexafluoroisopropylidene groups. The inherent viscosity, solubility, thermal stability, glass transition temperature, dielectric constant and homogeneity of thin film surfaces of these polymers have been studied.

Synthesis of fluorinated poly(phenylquinoxaline-amide)s and study of thin films made therefrom

A series of five fluorinated poly(phenylquinoxaline-amide)s were synthesized by a polycondensation reaction of a diacid chloride containing the hexafluoroisopropylidene (6F) group, namely 2,2-bis(p-chlorocarbonylphenyl)-hexafluoropropane, with various aromatic diamines incorporating two phenyl-substituted quinoxaline rings. These polymers were easily soluble in polar aprotic solvents such as N-methylpyrrolione (NMP), dimethylformamide (DMF), and tetrahydrofurane (THF), and showed a high thermal stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 260–290°C. Polymer solutions in NMP were processed into free-standing films that showed low dielectric constant values, in the range of 3.4–3.9, and good mechanical properties, with tensile strength in the range of 40–80 MPa and elongation to break in the range of 22–55%. Very thin films, in the range of tens of nanometer, which were deposited onto silicon wafers exhibited very smooth surfaces, free of pinholes when studied by atomic force microscopy (AFM).

Gas separation properties of pendent phenyl substituted aromatic polyamides containing sulfone and hexafluoroisopropylidene groups

Abstract The synthesis and gas transport properties of aromatic polyisophthalamides (PIPAs) based on isophthaloyl chloride (IPC) derivatives bearing a pendent phenyl group and a hexafluoroisopropylidene (6F) linkage in the main chain are reported. The properties of these polymers are compared with the properties of similar PIPAs containing sulfonyl (SO2) rather than 6F in the main chain. Polymers containing a phenyl pendent group at the five position of the isophthaloyl linkage are more permeable than those bearing only a hydrogen atom at this position, although increases in permeability are generally accompanied by decreases in selectivity. In the SO2-bearing polymer, the addition of a phenyl pendent group hinders chain packing more than in the 6F containing PIPAs. Consequently, permeability coefficients increase more upon addition of a pendent phenyl group in SO2-containing rather than 6F-containing PIPAs. The effect of amide linkage reversal on the gas transport properties of a polymer containing 6F linkages in the chain backbone and a hydrogen atom at the five position of the isophthaloyl linkage was minimal. All the PIPAs considered in this study were more permeable to nitrogen than to methane, some with nitrogen/methane selectivities of more than two.

Effect of bridging group in poly(titanyloxo-phthalocyanine)s on photocurrent generation

Abstract Photoelectric properties of soluble poly(titanyloxo-phthalocyanine)s, PTiOPc, in which phthalocynaine rings were bridged by carbonyl, sulfur dioxide, or alkylene groups, were investigated by using a photoelectrochemical techniques. Soluble poly(titanyloxophthaloeyanine) s were synthesized by the condensation of phthalic anhydride, dianhydrides, Ti(OBu) 4 , and urea in tetramethylene sulfone, followed by hydrolysis in an aqueous solution of KOH containing NaCl. Thin films of PTiOPc showed photocurrent of 2 ~ 10 μA/cm 2 upon excitation with a light above 560 nm under external potential of 0.6 V (vs Ag/AgCl). The intensity of the photocurrent was highly dependent on the polymer structure. Thin film of PTiOPc with carbonyl bridging groups showed highest photocurrent generation, whereas that with hexafluoroisopropylidene groups showed lower photocurrent. XRD of PTiOPc indicated that ordering of the polymer, induced by the bridging group, relates to the photocurrent.

Thermostable aromatic poly(1,3,4-oxadiazole)s from multi-ring flexible diacids

Abstract A series of aromatic poly(1,3,4-oxadiazole)s, PODZs, was prepared either by direct polycondensation of dicarboxylic acids with hydrazine sulfate using the polyphosphoric acid/methanesulfonic acid mixture, or by thermal cyclodehydration of the corresponding poly(hydrazide)s. Various aromatic diacids containing flexible p-oxyphenylene joints and/or bulky isopropylidene or hexafluoroisopropylidene groups in the main chain were used to produce amorphous PODZs soluble in strongly polar organic solvents and having inherent viscosities up to 1.1 dl g−1. The polymers were characterized by Fourier transform infrared and 1H and 13C nuclear magnetic resonance spectroscopy, and their thermal properties were investigated by differential scanning calorimetry and dynamic thermogravimetric analysis. The glass transition temperatures, Tg , lie in the range 190–295°C, and depend both on the number of aryloxy groups and on the presence of bulky groups. The PODZs show good thermal resistance in nitrogen up to 440°C.

Synthesis and Properties of Polyamide-Imide Based on 2, 2-Bis[4-(4-Aminophenoxy)Phenyl]Hexafluoropropane and 2, 2-Bis[4-(4-Aminophenoxy)Phenyl]Propane

Aromatic polyamide-imides having hexafluoroisopropylidene and isopropylidene groups in the main chain of the polymer were prepared by reacting 4-chloroformylphthalic anhydride (CPA) and fluorine or non-fluorine containing diamines using low-temperature polycondensation. Polyamide-imides were obtained with high molecular weight and high yield. Thermal decomposition temperature and glass transition temperatures of polymers were above 460 °C and 275 °C respectively. Fluorine and non-fluorine containing polyamide-imides were cast into transparent films which were characterized by mechanical and water absorption analysis.

Compared properties of aromatic polyamides containing silicon in the main chain

AbstractTwo series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups have been synthesized and their properties have been characterized and compared with those of related polymers. These polymers are easily soluble in polar amidic solvents such as N‐methyl‐2‐pyrrolidinone and dimethylformamide, and in tetrahydrofuran, and can be cast into thin, transparent films from solution. The polyamides have weight‐ and number‐average molecular weights in the range of 10 000–40 000 and 3 000–6 000, respectively, and polydispersities in the range of 3–10. They show glass transition temperatures in the range of 236°C–275°C and decomposition temperatures above 400°C. The polymer films have low dielectric constants in the range of 3.26–3.68, and good mechanical properties (tensile strength 74–100 MPa, tensile modulus 180–386 MPa), thus being comparable with other high performance dielectrics.

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.

Synthesis and properties of silicon-containing polyamides

A series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups has been synthesized by solution polycondensation of a silicon-containing diacid chloride with aromatic diamines having phenylquinoxaline rings or hexafluoroisopropylidene groups. These polymers are easily soluble in polar aprotic solvents, such as N-methylpyrrolidinone and dimethylformamide, and in tetrahydrofurane, and can be solution-cast into thin, transparent films having low dielectric constant, in the range of 3.26 to 3.68. These polymers show high thermal stability with decomposition temperature being above 400°C and glass transition temperature in the range of 236°C to 275°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1533–1538, 1997

Synthesis and properties of silicon‐containing polyamides

A series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups has been synthesized by solution polycondensation of a silicon-containing diacid chloride with aromatic diamines having phenylquinoxaline rings or hexafluoroisopropylidene groups. These polymers are easily soluble in polar aprotic solvents, such as N-methylpyrrolidinone and dimethylformamide, and in tetrahydrofurane, and can be solution-cast into thin, transparent films having low dielectric constant, in the range of 3.26 to 3.68. These polymers show high thermal stability with decomposition temperature being above 400°C and glass transition temperature in the range of 236°C to 275°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1533–1538, 1997

Heterocyclic polyamides containing hexafluoroisopropylidene groups

AbstractNew heterocyclic polyamides have been synthesized by solution polycondensation of aromatic diamines containing phenylquinoxaline units with diacid chlorides having both imide and hexafluoroisopropylidene (6F) groups. These polymers are soluble in polar aprotic solvents, such as N‐methylpyrrolidone (NMP) or N, N‐dimethylformamide (DMF), and can be cast into flexible thin films from solutions. They show high thermooxidative stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 225‐300°C. The polymer films exhibit good chemical resistance towards diluted acids and good electrical insulating properties with dielectric constants in the range of 3.2–3.7.

Synthesis and Characterization of New Fluorinated Poly(Imide Benzoxazole)S

We have prepared a series of fluorinated aromatic poly(ether imide benzoxazole)s (PEIBs) and fluorinated aromatic poly(imide benzoxazole)s (PIBs). New PEIBs were prepared by polycondensation of aromatic diamines containing both benzoxazole and hexafluoroisopropylidene groups. New PIBs were prepared by polycondensation of bis( o-aminophenol)s, such as 3,3′-dihydroxybenzidine or 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, with diacid chlorides containing both imide and hexafluoroisopropylidene groups. We have characterized the solubility, film forming ability, thermal stability and dielectric constant of these fluorinated poly(imide benzoxazole)s.

Fluorinated Poly(Phenylquinoxaline–Imide–Amide)S

Poly(phenylquinoxaline–imide–amide)s have been synthesized by solution polycondensation of aromatic diamines containing preformed phenylquinoxaline rings with a diacid chloride incorporating preformed imide rings and hexafluoroisopropylidene (6F) groups. These polymers do not decompose up to 400 °C and have glass transition temperatures in the range of 284–308 °C. They are soluble in polar amidic solvents, such as N-methyl-pyrrolidone, and in less polar solvents such as pyridine and tetrahydrofuran, and give flexible films by casting from solutions.

Miscibility of fluoro-containing polyimide blends

Experimental results confirm the general rules for miscible polyimide pairs containing the hexafluoroisopropylidene group if (1) the dianhydride composition is the same in each pair and (2) the diamine is changed from the 3,3′ (meta-substituted) 6F-diamine to the 4,4′ (para-substituted) 6F-diamine. These rules are also applicable to end-capped polyimide pairs. This conclusion is supported with the calculations of χ values based on the Flory-Huggins theory. We also discover two interesting polyimide alloys: 6FDA-PMDA-3,3′-6F-diamine/6FDA-PMDA 4,4′-6F-diamine forms fully miscible blends, while 6FDA-3,3′-6F-diamine/BTDA-4,4′-6F-diamine forms partially miscible blends (6FDA = hexafluorodianhydride, PMDA = pyromellitic dianhydride, BTDA = benzophenonetetracarboxylic dianhydride). These surprising results confirm that the rigidity, bond angle, space and the length of the dianhydride can significantly affect the molecular packing and miscibility tendency of polyimide blends.

Hexafluoroisopropylidene-Containing Polymers for High-Performance Applications

Abstract High-performance polymers are used in applications demanding service at enhanced temperature while maintaining their structural integrity and an excellent combination of chemical, physical, and mechanical properties. Some of the important polymers in this respect are polyimides, polyamides, and polybenzazoles. However, all of these polymers have a common problem of processing difficulty due to their infusibility and poor solubility in organic solvents. The reasons are strong interchain forces, inherent macromolecular rigidity, or semicrystallinity. A great amount of work has been directed to making polymers more tractable, soluble, and processable without sacrificing their high-performance characteristics. Thus, the last two decades have witnessed the spectacular growth of research in a new polymer type, the one containing hexafluoroisopropylidene (6F) groups. Incorporation of 6F units into the macromolecular chain increases the solubility, thermal stability, flame resistance, glass transition te...

Gas separation properties of aromatic polyamides containing hexafluoroisopropylidene groups

The synthesis and gas transport properties of aromatic polyisophthalamides (PIPAs), based on isophthaloyl chloride derivatives bearing pendent groups and hexafluoroisopropylidene (6F) linkages in the main chain, are reported and compared with properties of a similar series of PIPAs containing sulfonyl (SO2) rather than 6F in the main chain. All of those polymers exhibit high glass transitions temperatures. The polymers containing 6F groups were markedly more permeable and somewhat less selective than their sulfonyl analogs. Polymers containing a t-butyl pendent group at the 5 position of the isophthaloyl linkage were much more permeable than those bearing only a hydrogen atom at this position, although a strong decrease in permselectivity accompanied the large increase in permeability. CO2/CH4 solubility selectivity values of the 6F-containing polymers were similar to values reported for other polymetric and non-polymeric organic materials with similar concentrations of polar carbonyl linkages. In contrast, the CO2/CH4 solubility selectivity in SO2-containing variants of these polymers was substantially lower than expected based on total polar group concentration. The low CO2/CH4 solubility selectivity is believed to be related to the extremely efficient chain packing in the SO2-containing polymers, which may lead to strong amide-amide linkage interaction, thereby inhibiting carbonyl groups in the amide linkage from interactions with CO2 molecules to increase CO2/CH4 solubility selectivity.

Polyamide Copolymers Containing Hexafluoroisopropylene Groups

Abstract New copolymers containing imide and different heterocyclic units such as oxadiazole, benzoxazole, or pyridazine, together with hexafluoroisopropylidene groups, have been synthesized by solution polycondensation of appropriate aromatic diamines with diacid chlorides incorporating preformed imide rings and hexafluoroisopropylidene bridges. In the case of oxadiazole-imide copolymers and pyridazine-imide copolymers, aromatic diamines containing preformed oxadiazole or pyridazine, respectively, have been used, while in the case of benzoxazole-imide copolymers the benzoxazole unit was formed during the polycondensation reaction between bis(o-hydroxy-amine)s and the above-mentioned diacid chlorides. Also, copolyimides containing pendant cyano groups have been prepared from aromatic diamines containing cyano substituents with the same diacid chlorides. Solubility, film-forming ability, thermal stability, and electrical insulating properties of all these compounds are discussed and compared with those of ...