Search

Aromatic polyimides (PI1x) with a tetraphenylnaphthalene unit between ether linkages were synthesized from 1,4-bis[4-(aminophenoxy)phenyl]-2,3-diphenylnaphthalene (1) and various tetracarboxylic dianhydrides by a conventional two-step procedure that included ring-opening polymerization in N-methyl-2-pyrrolidone and subsequent thermal cyclic dehydration. PI1x were characterized by X-ray diffraction, differential scanning calorimetry, thermogravimetry, and dynamic mechanical analysis. PI1x had glass transition temperatures in the range of 270–315°C and all PI1x were amorphous. The structure–property relationships of these PIs were examined and compared with those of polyimides (PI2x) from 4,4′-bis(4-aminophenoxy)biphenyl (2) and polyimides (PI3x) from 1,4-bis(4-aminophenyl)-2,3-diphenylnaphthalene (3). Water absorption and dielectric constants ( ε) of the PIs were also compared and discussed on the basis of imide content per repeating unit.

Interest in atmospheric aerosol issues has been increasing worldwide. X-ray fluorescence (XRF) is an important atmospheric aerosol monitoring tool for inorganic component analysis, because XRF is a rapid and easy analysis method. In particular, Energy dispersive X-ray fluorescence (EDXRF) has drawn attention for aerosol analysis. However, EDXRF has difficulties that: (1) many overlapping peaks exist for aerosol filter analysis and (2) many thin-film standard samples are required when an empirical calibration method is employed. Accurate analysis method of aerosol filter samples without the need for large sets of standards by semi-quantitative analysis software RPF–SQX (Rigaku profile fitting–spectra quant X), which includes the exact profile fitting and thin-film fundamental parameter (FP) method, is described using the EDXRF spectrometer equipped with secondary targets and polarized optics.

Diamines, namely, 1,4-bis(4-amino-2-phenylphenoxy) benzene (1) and 4,4′-bis(4-amino-2-phenylphenoxy) biphenyl (2), were synthesized from 4-fluoro-3-phenyl nitrobenzene. Two series of polyimides were synthesized from these diamines with nine types of dianhydrides by a conventional two-step procedure that included ring-opening polymerization in N-methyl-2-pyrrolidone and subsequent thermal cyclic dehydration. The polyimides were characterized by x-ray diffraction, differential scanning calorimetry, thermogravimetry and dynamic mechanical analysis. The polyimides from 1 and 2 had a glass transition temperature in the range of 221–254°C and 222–271°C, respectively, and all the polymers were amorphous. The structure–property relationships of these polyimides were examined and compared with those of the previously prepared analogous polyimides from the bis(4-amino-2-biphenyl)ether (3). Water absorption and dielectric constants ( ∊) of the polyimides were compared and discussed on the basis of imide content per repeating unit.

New polyimide–silica hybrid materials were prepared using the polyamic acid synthesized by copolymerization of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 4,4′-oxydianiline (ODA) and an A 2 A′-type tri-functional amine, 1,1-bis(4-(aminophenoxy)phenyl)-1-(4-(4-amino-2-trifluoromethylphenoxy)phenyl)ethane (1) (BTDA:ODA:1 = 7:6:1 in the molar). 3-(Triethoxysilyl)propyl succinic anhydride(TESSA) was reacted with amino groups in polyamic acid to introduce ethoxysilyl moiety which act as conjugation site for silica. The polyimide–silica hybrid films were prepared by a sol–gel reaction of tetraethoxysilane (TEOS) in a solution of the polyamic acid, followed by thermal imidation. Self-standing films were obtained with up to 50 wt.% silica, and transparent films were obtained at up to 40 wt.% silica. Dynamic-mechanical and mechanical analyses were carried out to examine the properties of hybrid films.

A new diamine, 1,1-bis[4-(4-aminophenoxy)phenyl]-1-(4-hydroxyphenyl)ethane, was synthesized in three steps starting from 1,1,1-tris(4-hydroxyphenyl)ethane. New aromatic polyimides having hydroxy side groups were prepared from this diamine and various tetracarboxylic dianhydrides by the conventional two-step procedure that included ring-opening polymerization in N-methyl-2-pyrrolidone (NMP) and subsequent thermal cyclic dehydration. The polyimides were characterized by X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry (TG), and dynamic mechanical analysis (DMA). All the polyimides were amorphous, and had glass transition temperature ( Tg) in the range of 232—304 °C. The properties of polyimides were compared with those of polyimides prepared from 1,1-bis[4-(4-aminophenoxy)phenyl]-1-phenylethane, which had no hydroxy side groups. The effects of the hydroxy side groups were observed in the thermal properties, thermal mechanical properties and solubility of polyimides.

A novel sulfonated diamine bearing aromatic sulfophenyl pendant groups, named as, 2,2′-bis(4-sulfophenyl)-4,4′-oxydianiline (SPhODA) was synthesized. Sulfonated (co)polyimides (SPIs) with flexible ether linkage in the main chain and sulfophenyl groups in the side chain were synthesized from SPhODA, 1,4,5,8-naphthalene tetracarboxylic dianhydride and nonsulfonated diamines. The SPI membranes showed good solubility in common aprotic solvents and high desulfonation temperature of 320 °C. The SPIs with ion exchange capacities of 1.57–2.50 meq g −1 displayed reasonably high proton conductivities of 0.09–0.21 S cm −1 at 60 °C in water and 0.02–0.05 S cm −1 at 70% relative humidity. They also displayed high mechanical properties, but their water stability was not enough high at high temperatures. They showed high potential for DMFC application at low and/or mediate temperatures.

Aromatic polyimides having phenyl groups at the 2- and 2′-positions of the diphenyl ether moiety were synthesized from bis(4-amino-2-biphenyl) ether and various tetracarboxylic dianhydrides by the conventional two-step procedure using N-methyl-2-pyrrolidone (NMP) as a solvent [Morikawa et al., Polymer Journal37, 759, 2005]. The phenyl groups at the 2,2′-position of the phenyl ether improved the solubility of polyimides without decreasing the thermal and thermo-mechanical properties. In this paper, soluble polyimides were synthesized in a one-step procedure by reacting this diamine with various tetracarboxylic dianhydrides in m-cresol at 190°C, and the properties, especially the thermal properties, thermo-mechanical properties and solubility were compared with those of the polyimides synthesized by the two-step procedure.

A new phenylated diamine, bis(4-amino-2-biphenyl)ether, was synthesized in five steps starting from 3-chloro-4-fluoronitrobenzene. New aromatic polyimides having phenyl groups at the 2- and 2′-positions of the diphenyl ether moiety were prepared from this diamine and various tetracarboxylic dianhydrides by the conventional two-step procedure that included ring-opening polymerization in NMP and subsequent thermal cyclic dehydration. The polyimides were characterized by differential scanning calorimetry (DSC), thermogravimetry, and dynamic mechanical analysis (DMA). Typical polyimides showed excellent thermal stability, and had glass transition temperature (Tg) above 250 °C. As for the series of polyimides prepared from tetracarboxylic anhydrides having linear phenylene moiety, the introduction of phenyl group at the 2- and 2′-positions of phenyl ether improved thermal and thermo-mechanical properties as well as the solubility of polymers.

We have prepared aromatic polyimides PI-Ar- m containing p-quarterphenyl ( m = 2) and p-sexiphenyl ( m = 4) units. [ILLEGIBLE] These polyimides are characterized by having long phenylene units and the introduction of these has a strong influence on the properties of polyimides. In this paper, the properties of polyimides are compared with those of polyimides from 3,3″,4,4″- p-terphenyltetracarboxylic dianhydride ( m = 1) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride ( m = 0), which had been previously prepared, and discussed on the basis of the number ( m) of phenylene units in the dianhydrides.

Chiral phenylindanediamnine (+)-2 was synthesized starting from chiral phenyl-indanedicarboxylic acid by a Schmidt rearrangement. Ordered amine-acid AB-type monomers, 8 and 9, were also prepared by a controlled reaction of (+)-2 with diacid chlorides. Disordered and ordered polyamides were synthesized by the reaction of (+)-2 with dicarboxylic acids, and the self-condensation of 8 and 9, respectively. Both the ordered and disordered polyamides were soluble in various solvents. The polyamides composed of the same dicarboxylic acid prepared by the different routes showed the same circular dichroism spectra. X-ray diffraction of the polyamide films indicated that all of the polyamides were amorphous. The glass transition and decomposition temperatures ranged from 170 to 340°C and from 320 to 400 °C, respectively. Additionally, polyamides containing the same diacids displayed nearly equivalent physical properties.

An optically pure isomer of 1,l,3.-trimethyl-3-phenylindane-4',5-dicarboxylic acid (PIDA) was obtained by introduction of racemric PIDA to a diester of the optically pure alcohol. D-(-)-pantolactone, followed by hydrolysis of the separated stereoisomer of the diester. Optically active aromatic polyamides (aramids) were synthesized by the reaction of the optically pure PIDA with various aromatic diamines. The specific rotations of these aramids ranged from + 284 to +4416. The aramids were soluble in organic solvents such as N,N-dimethylacetamide, pyridine and m-cresol. These materials had glass transition temperatures over 290 'C, and did not decompose below 380 C. The solubility and thermal behaviour were almost the same as those of the racemic aramids. The optically active aramids were examined as a stationary phase for chromatographic enantioseparation. When the aramid derived from p-phenylenediamine was used for this purpose, the stereoisomers of l-phenylethylamine could be easily separated.

After a description of the preparation of polymer-metal oxide hybrid materials via the sol-gel method, recent results on the preparation of new polyimide-silica hybrid materials are reviewed. Tetraethoxysilane (TEOS) can be hydrolysed and polycondensed to form a three-dimensional silica-gel network in a solution of polyamic acids, the precursor polymers of polyimides, and N,N-dimethylacetamide (DMAc). Films of the polyamic acid-silica gel mixtures can be cast onto glass plates, and can then be heated to 300 °C to convert the component matrix polymers to polyimides. Five kinds of polyamic acid have been designed and prepared. One of them was the usual polyamic acid, having no connection site with silica, whereas others had ethoxysilyl groups in the polymer backbone. The polyimide-silica hybrid films containing 70 wt.% of silica were self-standing and tough. The transparent-opaque changing points shifted to higher silica content with increasing ethoxysilyl-group content of the matrix polyimides. The silica particles were dispersed homogeneously in the matrix polyimides, as observed by scanning electron microscopy. The size of the silica particles increased with increasing silica content, and decreased with increasing ethoxysilyl content. Results of the dynamic-mechanical analysis indicate that movement of the polyimide chain in the matrix is restricted, especially when the polyimides contain higher amounts of ethoxysilyl. The tensile strength of the hybrid films showed no decrease with increasing silica content, whereas the tensile modulus increased in all cases except that where the matrix polyimide did not contain any ethoxysilyl groups.