Atsushi Morikawa
Ibaraki University
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Featured researches published by Atsushi Morikawa.
High Performance Polymers | 2010
Arata Satoh; Atsushi Morikawa
Aromatic polyimides, which had trifluoromethyl group at 2,2′-position of the diphenyl ether, were synthesized from bis(4-amino-2-trifluoromethylphenyl)ether (1) and previously prepared tetracarboxylic dianhydrides, 3,3′′′,4,4 ′′′-p-quaterphenyltetracarboxylic dianhydride (2d), 3,3′′′ ′,4,4′′′ ′-p-quinquephenyltetracarboxylic dianhydride (2e) and 3,3′ ′ ′ ′ ′ ,4,4 ′ ′ ′ ′ ′ -p-sexiphenyltetracarboxylic dianhydride (2f), and the properties were compared than those of corresponding polyimides from commercially available tetracarboxylic dianhydrides. The polyimides were synthesized by the conventional two-step procedure of ring-opening polyaddition in N-methyl-2-pyrrolidinone (NMP) and subsequent thermal cyclic dehydration. The polyimides were characterized by differential scanning calorimetry (DSC), thermogravimetry, and dynamic mechanical analysis (DMA). The polyimides showed excellent thermal stability, and had glass transition temperature (T g) at 234—300 °C. The properties of polyimides were compared with those of previously prepared polyimides, which had phenyl group at 2,2′-position of the diphenyl ether, and the effect of the trifluoromethyl groups at the 2, 2′- positions of the diphenyl ether were observed in the thermal properties, solubility and optical properties of polyimides.
High Performance Polymers | 2006
Atsushi Morikawa; Takaaki Furukawa; Yukari Moriyama
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 Journal 37, 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.
High Performance Polymers | 2001
Atsushi Morikawa; Katsumichi Ono
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.
High Performance Polymers | 2012
Atsushi Morikawa; Fumi Miyata; Jun Nishimura
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.
Molecules | 2016
Atsushi Morikawa
Poly(ether ether ketone) dendrimers and hyperbranched polymers were prepared from 3,5-dimethoxy-4′-(4-fluorobenzoyl)diphenyl ether and 3,5-dihydroxy-4′-(4-fluorobenzoyl)diphenyl ether through aromatic nucleophilic substitution reactions. 1-(tert-Butyldimethylsiloxy)-3,5-bis(4-fluorobenzoyl)benzene was polycondensed with bisphenols, followed by cleavage of the protective group to form linear poly(ether ketone)s having the same hydroxyl groups in the side chains as the chain ends of the dendrimer and hyperbranched polymers. Their properties, such as solubilities, reduced viscosities, and thermal properties, were compared with one another. Similar comparisons were also carried out among the corresponding methoxy group polymers, and the size of the molecules was shown to affect the properties.
High Performance Polymers | 2010
Takahiro Okabe; Atsushi Morikawa
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 (T g) 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.
High Performance Polymers | 2015
Syuta Nabeshima; Atsushi Morikawa
Aromatic polyimides (PIs) with a hexaphenylbenzene unit were synthesized from 1,4-bis[4-(4-aminophenoxy)phenyl]-2,3,5,6-tetraphenylbenzene (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. The PIs were characterized by X-ray diffraction, differential scanning calorimetry, thermogravimetry, and dynamic mechanical analysis. The PIs had glass transition temperatures in the range of 289–352°C, and all the polymers were amorphous. The structure–property relationships of these PIs were examined and compared with those of the previously prepared analogous PIs from 4,4′-bis(4-aminophenoxy)biphenyl (2) and 4,4′-bis(4-amino-2-phenylphenoxy)biphenyl (3). Water absorption and dielectric constants of the PIs were also compared and discussed on the basis of imide content per repeating unit.
High Performance Polymers | 1995
Atsushi Morikawa; Masa-aki Kakimoto; Yoshio Imai
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.
High Performance Polymers | 1994
Atsushi Morikawa; Masa-aki Kakimoto; Yoshio Imai
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.
High Performance Polymers | 2018
Satoshi Kawaguchi; Atsushi Morikawa
Three kinds of bis(aromatic fluoride) compounds, 3,5-bis(4-fluorobenzoyl)biphenyl (1), 3,5-bis(4-fluorobenzoyl)-1,1′:4′,1″-terphenyl (2), and 3,5-bis(4-fluorobenzoyl)-1,1′:4′,1″:4″,1′′′-quaterphenyl (3), were synthesized by cross-coupling of the corresponding triflates with phenylboronic acid. Linear poly(ether ketone)s (1x, 2x, and 3x) having phenyl, biphenyl, and terphenyl side groups, respectively, were prepared by the polycondensation of the bis(aromatic fluoride) compounds with bisphenol A (a) and 4,4′-dihydroxybiphenyl (b) in N-methyl-2-pyrrolidone. The obtained poly(ether ketone)s were characterized by X-ray diffraction, differential scanning calorimetry, and thermogravimetry. The structure–property relationships of these poly(ether ketone)s were examined and compared with those of poly(ether ketone)s (4x) having no side group, which were prepared from 3,5-bis(4-fluorobenzoyl)benzene (4). The properties of the poly(ether ketone)s, solubilities, and thermal properties were compared and discussed based on the length of the side groups.