The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Masayoshi Watanabe - One of the best experts on this subject based on the ideXlab platform.
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high ionic conductivity of polyether based Network Polymer electrolytes with hyperbranched side chains
Macromolecules, 1999Co-Authors: Atsushi Nishimoto, Kunihiro Agehara, Noriyuki Furuya, Toshiyuki Watanabe, Masayoshi WatanabeAbstract:To achieve solvent-free Polymer electrolytes with high ionic conductivity, Network Polymer electrolytes with hyperbranched ether side chains were synthesized. A monosubstituted epoxide monomer, 2-(...
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Network Polymer Electrolytes with Free Chain Ends as Internal Plasticizer
Journal of The Electrochemical Society, 1998Co-Authors: Michiyuki Kono, Eriko Hayashi, Masayoshi WatanabeAbstract:Novel Polymer electrolytes based on Network Polymers with free chain ends have been prepared, and the effects of the free chain ends on the thermal and mechanical properties, the ionic conductivity, and the charge-transfer resistance at the lithium electrode interface have been explored in detail. Terminal hydroxyl groups of poly(ethylene oxide-copropylene oxide) triol (MW 7940) were partly methylated, and the residual hydroxyl groups were esterifited by acrylic acid. The resulting macromonomers were cross-linked by photoirradiation in the presence of an electrolyte salt to produce the Network Polymer electrolytes. The free chain ends, caused by the methylation, were proved to function as an immobile internal plasticizer, as demonstrated by the decreases in the glass transition temperature and the elastic modulus with increasing number of free chain ends; however, creep-free mechanical strength was maintained due to the cross-linked structure. The introduction of free chain ends not only increased the bulk ionic conductivity but also reduced the charge-transfer resistance. As a result, Network Polymer electrolytes having a large number of the free chain ends exhibited an ionic conductivity of 10 -3 S cm -1 and a charge-transfer resistance of 20 cm 2 at 80°C when lithium bis(trifluoromethylsulfonyl)imide was used as an electrolyte salt.
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Open spaces and molecular motions of polyether‐based Network Polymers probed by positron annihilation
Journal of Polymer Science Part B: Polymer Physics, 1998Co-Authors: Akira Uedono, Masayoshi Watanabe, S. Tanigawa, Atsushi NishimotoAbstract:The lifetimes of positrons have been measured for Network Polymers based on polyethers. From the temperature dependence of the lifetime of ortho-positronium (o-Ps), τ3, for the Network Polymer of poly(ethylene oxide-co-propylene oxide) [P(EO/PO)], an onset temperature for limited local motions of molecules, Tγ, and the glass transition temperature, Tg, were determined to be 57 and 201 K, respectively. For the Network Polymer of poly[EO-co-2-(2-methoxyethoxy)ethyl glycidyl ether] [P(EO/MEEGE)], Tγ and Tg were determined to be 57 and 185 K, respectively. For both specimens, above 270 K, the observed linear temperature dependence of τ3 was attributed to the thermal expansion of open spaces in a liquid state. In the temperature range between Tγ and 270 K, for the P(EO/MEEGE) Network, τ3 was longer and its intensity was smaller than those for the P(EO/PO) Network. These results were attributed to the increase in the size of open spaces for the P(EO/MEEGE) Network Polymer and the blocking of these regions by motions of side chains and chain ends. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1919–1925, 1998
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molecular relaxations of a branched pely oxyethylene Network Polymer
横浜国立大学機器分析センター年報, 1997Co-Authors: Kimio Ichikawa, Charles L Dickinson, William J Macknight, Masayoshi WatanabeAbstract:Dielectric relaxation measurements and i 3C NMR measurements were carried out on an amorphous Network Polymer derived from poly(2-(2-methoxyethoxy)ethyl glycidyl ether)triol with 2,4-toluenediisocyanate. The main relaxation and the higher'freque.ncy relaxation were observed in the dielectric spectra. The main relaxation was found to be symmetrical and broad with a half width of. 5 decades in a frequency domain. The higher frequency process is considered to be theγ process or ethylene oxide chains due to the local twisting mode. The temperature depehdence of TI and Tiρof the ethylene oxide carbon showed minima and it is clearly shown that the relaxation times obtained from the dielectric measurements correspond to the relaxation'time obtained from the T1 b measurements ofthe ethylene oxide carbon. The temperature dependence ・f・Tl w・・w・11・d・・c・ib・d assumi・g th・C・1・-C・1・・pect・al d…ity f…ti・n with th・・h・p・fa・t・・β・bt・in・d f・r th・di・1ect・i・ main relaxation, The i 3C magnetization decay' of the ethylene oxide carbon in the rotating frame was found to be given by two components(slow artd f這st components)below the relaxation temperature. The broad dielectric relaXation and the decay P,。fil…fthe ethy1・n…ide ca・b・…edi・cussed i・t・・m・・f th・bt…h・d・t・u・t・・e・f th・n・tw・rk・t-
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molecular relaxations of a branched poly oxyethylene Network Polymer
Polymer Journal, 1997Co-Authors: Kimio Ichikawa, Charles L Dickinson, William J Macknight, Masayoshi WatanabeAbstract:Dielectric relaxation measurements and 13C NMR measurements were carried out on an amorphous Network Polymer derived from poly[2-(2-methoxyethoxy)ethyl glycidyl ether]triol with 2,4-toluenediisocyanate. The main relaxation and the higher frequency relaxation were observed in the dielectric spectra. The main relaxation was found to be symmetrical and broad with a half width of 5 decades in a frequency domain. The higher frequency process is considered to be the γ process of ethylene oxide chains due to the local twisting mode. The temperature dependence of T1 and T1ρ of the ethylene oxide carbon showed minima and it is clearly shown that the relaxation times obtained from the dielectric measurements correspond to the relaxation time obtained from the T1ρ measurements of the ethylene oxide carbon. The temperature dependence of T1 was well described assuming the Cole-Cole spectral density function with the shape factor β obtained for the dielectric main relaxation. The 13C magnetization decay of the ethylene oxide carbon in the rotating frame was found to be given by two components (slow and fast components) below the relaxation temperature. The broad dielectric relaxation and the decay profiles of the ethylene oxide carbon are discussed in terms of the branched structure of the Network.
Shuang Fang - One of the best experts on this subject based on the ideXlab platform.
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novel composite Polymer electrolytes based on poly ether urethane Network Polymer and fumed silicas
Journal of Solid State Electrochemistry, 2006Co-Authors: Xiangrong Wang, Junjie Kang, Yuping Wu, Hui Zhang, Shuang FangAbstract:Novel composite solid Polymer electrolytes (CSPEs) and composite gel Polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) Network Polymer (PUN), fumed silicas and LiClO4. The ionic conductivity of CSPEs can be enhanced nearly 20 times in comparison with the plain system without the addition of fumed silicas and can be above 1×10−5 S/cm at room temperature. The effects of both kinds of fumed silicas, viz. uSiO2 with hydrophilic groups at the surface and mSiO2 with hydrophobic groups at the surface on ionic conductivity were investigated. CGPE comprising of the CSPE and LiClO4–PC solution with good mechanical strength exhibits ionic conductivity in the order of 10−3 S/cm at room temperature and above 3×10−4 S/cm at low temperature −40 °C.
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novel composite Polymer electrolytes based on poly ether urethane Network Polymer and modified montmorillonite
Electrochemistry Communications, 2003Co-Authors: X.j. Wang, Junjie Kang, Yuping Wu, Shuang FangAbstract:Abstract Novel composite solid Polymer electrolytes (CSPEs) and composite gel Polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) Network Polymer, which is superior to poly(ethylene oxide) in mechanical stability due to its cross-linked structure, modified montmorillonite (MMMT) and LiClO4, and CGPE with good mechanical strength comprises of the CSPE and LiClO4–PC (propylene carbonate) solution. The ionic conductivity can be enhanced after the addition of MMMT, and CGPE exhibits ionic conductivity in the order of 10−3 S/cm at room temperature. The temperature dependence of the ionic conductivity of the CSPE follows the Vogel–Tamman–Fulcher (VTF) equation. The effects of MMMT on the interactions in these systems and the possible conduction mechanisms are also discussed.
Akira Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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Construction of Crosslink-System-Materials Utilizing Designed Network-Polymer-Precursor Modules
Macromolecular Symposia, 2011Co-Authors: Akira MatsumotoAbstract:For a long time, we have been concerned with the elucidation of Network formation mechanism of free-radical crosslinking (co)Polymerization of multivinyl monomers. We have pursued two extreme Network structures formation such as ideal and nanogel-like NPP formation. During the course of these investigations, we recognized that a Network Polymer may be reconsidered as a crosslink-system-material (CSM) or a giant system consisting of Network Polymer precursor (NPP) modules. The Network Polymer is not a giant molecule as a smallest unit of matter which could behave as one molecule. According to this definition, our subject may be changed from the molecular design of Network Polymer to the molecular design of NPP based on the free-radical crosslinking multivinyl Polymerization mechanism. Then, we could construct a variety of CSMs utilizing designed NPP modules. A variety of CSM constructions are exemplified.
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Microgel-like Network Polymer precursor formation in free-radical cross-linking multiallyl Polymerization
Polymer Journal, 2010Co-Authors: Hiroyuki Hamamoto, Hiroyuki Aota, Kota Himei, Satoshi Inoue, Akira MatsumotoAbstract:The present study is an extension of our preceding work on gelation behavior. We observed no substantial difference in the actual gel points among three isomeric diallyl phthalates: diallyl phthalate, diallyl isophthalate and diallyl terephthalate. The resulting Network Polymer precursors (NPPs) were characterized by size-exclusion chromatography with both multiangle laser light scattering and viscometry. It is of note that the structure of NPP, consisting of oligomeric primary Polymer chains, becomes core-shell type dendritic or nanogel-like with the progress of Polymerization. The nanogel-like NPPs can then collide with one another to form cross-links, eventually leading to gelation. Although the concentration of NPP should be high at the conversion close to the gel point, the dilution of NPP by adding monomer could prevent the cross-link formation among NPPs, and consequently lead to the successive growth of high-molecular-weight NPP from a nanogel to a microgel. The further growth of the microgel as an inhomogeneous NPP with high cross-link density could eventually reach an extremely inhomogeneous Network Polymer. These processes were pursued as typical examples using the bulk Polymerization of DAT. In the free-radical cross-linking multiallyl Polymerization, the structure of Network Polymer precursor (NPP) consisting of oligomeric primary Polymer chains would become core-shell type dendritic or nanogel-like with the progress of Polymerization and then, the NPPs can collide with each other to form cross-links among NPPs, eventually leading to gelation. Thus, the dilution of NPP by newly adding monomer could prevent the cross-link formation between NPPs and consequently, lead to the successive growth of NPP from nanogel to microgel.
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Microgel-like Network Polymer precursor formation in free-radical cross-linking multiallyl Polymerization
Polymer Journal, 2010Co-Authors: Hiroyuki Hamamoto, Hiroyuki Aota, Kota Himei, Satoshi Inoue, Akira MatsumotoAbstract:The present study is an extension of our preceding work on gelation behavior. We observed no substantial difference in the actual gel points among three isomeric diallyl phthalates: diallyl phthalate, diallyl isophthalate and diallyl terephthalate. The resulting Network Polymer precursors (NPPs) were characterized by size-exclusion chromatography with both multiangle laser light scattering and viscometry. It is of note that the structure of NPP, consisting of oligomeric primary Polymer chains, becomes core-shell type dendritic or nanogel-like with the progress of Polymerization. The nanogel-like NPPs can then collide with one another to form cross-links, eventually leading to gelation. Although the concentration of NPP should be high at the conversion close to the gel point, the dilution of NPP by adding monomer could prevent the cross-link formation among NPPs, and consequently lead to the successive growth of high-molecular-weight NPP from a nanogel to a microgel. The further growth of the microgel as an inhomogeneous NPP with high cross-link density could eventually reach an extremely inhomogeneous Network Polymer. These processes were pursued as typical examples using the bulk Polymerization of DAT.
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Development of a variety of novel Polymers originated from multiallyl cross-linking Polymerization
Designed Monomers and Polymers, 2004Co-Authors: Akira Matsumoto, Hiroyuki AotaAbstract:Here, as part of our continuing studies concerned with the Network formation mechanism in the free-radical cross-linking Polymerization and co-Polymerization of multivinyl monomers, we briefly reviewed the development of a variety of novel Polymers originated from multiallyl cross-linking Polymerization. The formation processes of the ideal Network Polymer governed by the Flory–Stockmayer gelation theory, the microgel and the semi-interpenetrating Polymer Network (semi-IPN) were employed to develop novel Polymers by a combination with allyl Polymerization leading to short Polymer chain formation and intramolecular cross-linking as a key reaction of Network formation generating Network structure. These include amphiphilic pre-Polymers and Network Polymers derived from ideal Network Polymer, core/corona nanoparticles derived from pseudo-microgel, topological Polymers as semi-IPN precursors and centipede Polymers as primary Polymer chains of Network Polymers having abundant dangling chains.
Yuping Wu - One of the best experts on this subject based on the ideXlab platform.
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novel composite Polymer electrolytes based on poly ether urethane Network Polymer and fumed silicas
Journal of Solid State Electrochemistry, 2006Co-Authors: Xiangrong Wang, Junjie Kang, Yuping Wu, Hui Zhang, Shuang FangAbstract:Novel composite solid Polymer electrolytes (CSPEs) and composite gel Polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) Network Polymer (PUN), fumed silicas and LiClO4. The ionic conductivity of CSPEs can be enhanced nearly 20 times in comparison with the plain system without the addition of fumed silicas and can be above 1×10−5 S/cm at room temperature. The effects of both kinds of fumed silicas, viz. uSiO2 with hydrophilic groups at the surface and mSiO2 with hydrophobic groups at the surface on ionic conductivity were investigated. CGPE comprising of the CSPE and LiClO4–PC solution with good mechanical strength exhibits ionic conductivity in the order of 10−3 S/cm at room temperature and above 3×10−4 S/cm at low temperature −40 °C.
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novel composite Polymer electrolytes based on poly ether urethane Network Polymer and modified montmorillonite
Electrochemistry Communications, 2003Co-Authors: X.j. Wang, Junjie Kang, Yuping Wu, Shuang FangAbstract:Abstract Novel composite solid Polymer electrolytes (CSPEs) and composite gel Polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) Network Polymer, which is superior to poly(ethylene oxide) in mechanical stability due to its cross-linked structure, modified montmorillonite (MMMT) and LiClO4, and CGPE with good mechanical strength comprises of the CSPE and LiClO4–PC (propylene carbonate) solution. The ionic conductivity can be enhanced after the addition of MMMT, and CGPE exhibits ionic conductivity in the order of 10−3 S/cm at room temperature. The temperature dependence of the ionic conductivity of the CSPE follows the Vogel–Tamman–Fulcher (VTF) equation. The effects of MMMT on the interactions in these systems and the possible conduction mechanisms are also discussed.
Toshio Koizumi - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Network Polymer emitters: tunable detection of chemicals by geometric design
Polymer Journal, 2019Co-Authors: Shotaro Hayashi, Shin-ichi Yamamoto, Koji Nishi, Atsushi Asano, Toshio KoizumiAbstract:Conjugated Network Polymer emitters are potential materials for use as solid detectors of chemicals. We demonstrated the synthesis of fluorescent Network Polymers through a facile route. Solid-state fluorescent Network Polymer emitters were synthesized through the Knoevenagel polycondensation of an arylaldehyde (tris( p -formylphenyl)amine) with an arylacetonitrile (phenylenediacetonitrile) in good yields. The molecular structure based on the electron-donor triphenylamine and electron-acceptor cyano-substituted phenylene-vinylene showed a highly efficient solid-state fluorescence. The synthesized model small molecule showed a well-defined solvatofluorochromism: the dielectric constants were ε _sol of approximately 0–50 at λ _fl of 480–560 nm. The response to solvent chemicals was also shown for the Network Polymers. Surprisingly, the Network Polymer linked with para -phenylene-vinylene was only responsive to the solvents with a low dielectric constant ( ε _sol ca.
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Synthesis of Network Polymer emitters: tunable detection of chemicals by geometric design
Polymer Journal, 2019Co-Authors: Shotaro Hayashi, Shin-ichi Yamamoto, Koji Nishi, Atsushi Asano, Toshio KoizumiAbstract:Conjugated Network Polymer emitters are potential materials for use as solid detectors of chemicals. We demonstrated the synthesis of fluorescent Network Polymers through a facile route. Solid-state fluorescent Network Polymer emitters were synthesized through the Knoevenagel polycondensation of an arylaldehyde (tris(p-formylphenyl)amine) with an arylacetonitrile (phenylenediacetonitrile) in good yields. The molecular structure based on the electron-donor triphenylamine and electron-acceptor cyano-substituted phenylene-vinylene showed a highly efficient solid-state fluorescence. The synthesized model small molecule showed a well-defined solvatofluorochromism: the dielectric constants were esol of approximately 0–50 at λfl of 480–560 nm. The response to solvent chemicals was also shown for the Network Polymers. Surprisingly, the Network Polymer linked with para-phenylene-vinylene was only responsive to the solvents with a low dielectric constant (esol ca.