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Nobukatsu Nemoto - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and characterization of poly(tetramethylsilarylenesiloxane) derivatives with oligothiophene based moiety
Polymer, 2019Co-Authors: Ibuki Nishizawa, Hiroki Ajito, Yuzuki Gonmori, Ryuzi Katoh, Tsukasa Ichikawa, Nobukatsu NemotoAbstract:Abstract Poly(tetramethylsilarylenesiloxane) derivatives (P1T-P4T, P4TC) that contained thiophene (1T), oligothiophenes such as dithiophene (2T), terthiophene (3T), quaterthiophene (4T), or 2,6-di(2-thienyl)-4,4-diphenylcyclopentadithiophene (4TC) as the main chain components were synthesized via polycondensation reaction of the corresponding Disilanol monomers (M1T-M4T, M4TC). The obtained polymers other than P4T that contained quaterthiophene units exhibited the good solubility in common organic solvents, such as toluene, chloroform, tetrahydrofuran and so on. The glass transition temperature (Tg) and melting temperature (Tm) of the obtained polymers regarding P1T-P4T were increased with the extension of the thiophene rings of the monomeric unit as deduced from the results of the differential scanning calorimetry (DSC). On the other hand, the Tm was not observed for P4TC that was composed of 2,6-di(2-thienyl)-4,4-diphenylcyclopentadithiophene units. P2T that was composed of dithiophene units exhibited the highest temperature at 5% weight loss (Td5) of 467 °C in all present polymers. The bathochromic and hyperchromic effects in the absorption spectra as well as the improvement of fluorescence quantum yield were observed by the introduction of dimethylsilyl group onto the present oligothiophene derivatives. These effects became unremarkable accompanying the elongation of the thiophene rings of the monomeric units; however, 4TC exhibited a more significant change by the introduction of the dimethylsilyl group than the other oligothiophenes derivatives, indicating that the introduction of the cardo-structure was effective in the improvement of the optical properties. M4TC and P4TC exhibited the fluorescence wavelength around 500 nm and the highest fluorescence quantum yield of the present series of poly(tetramethylsilarylenesiloxane) derivatives, i.e., 0.40, plausibly because the free rotation between thiophene rings in oligothiophene inhibited by the cardo-structures and the bulky diphenyl groups at 4-position of cyclopentadithiophene moiety suppressed the nonradiative transition.
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Synthesis and optical properties of poly(tetramethylsilarylenesiloxane) derivative bearing diphenylcyclopentadithiophene moiety
Polymer, 2014Co-Authors: Hitoshi Hanamura, Nobukatsu NemotoAbstract:Abstract The thermal and optical properties of a novel diphenylcyclopentadithiophene-based poly(tetramethylsilarylenesiloxane) derivative ( P1 ), which was prepared via polycondensation of a novel Disilanol monomer, i.e., 2,6-bis(dimethylhydroxysilyl)-4,4-diphenylcyclopentadithiophene ( M1 ), were investigated. P1 exhibited good solubility in common organic solvents, such as benzene, toluene, chloroform, dichloromethane and THF at ambient temperature. The glass transition temperature ( T g ) of P1 was determined by differential scanning calorimetry to be 109 °C. No melting temperature ( T m ) of P1 was observed, indicating the obtained P1 was an amorphous polymer. The temperature at 5% weight loss ( T d 5 ) of P1 was 454 °C, indicating the rather good thermostability of P1 . Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra by introducing dimethylsilyl substituents onto 4,4-diphenylcyclopentadithiophene skeleton. The fluorescence quantum yields ( Φ F s) of M1 and P1 in chloroform were determined to be 0.36 and 0.39, respectively. It was revealed that M1 and P1 exhibited the higher fluorescence intensity than diphenylcyclopentadithiophene owing to the cooperative effects of the introduction of diphenyl groups onto spiro carbon of cyclopentadithiophene as well as dimethylsilyl moieties onto 2- and 6-position of cyclopentadithiophene skeleton.
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Synthesis and characterization of poly(tetramethylsilarylenesiloxane) derivatives bearing benzodithiophene moieties
Reactive and Functional Polymers, 2014Co-Authors: Hitoshi Hanamura, Ryoichi Hattori, Ryo Maruyama, Nobukatsu NemotoAbstract:Abstract Poly(tetramethylsilarylenesiloxane) derivatives bearing benzo[1,2-b;4,5-b′]dithiophene (P1) and benzo[2,1-b;3,4-b′]dithiophene (P2) moieties were prepared via polycondensation of the corresponding Disilanol monomers, that is, 2,6-bis(dimethylhydroxysilyl)benzo[1,2-b;4,5-b′]dithiophene (M1) and 2,7-bis(dimethylhydroxysilyl)benzo[2,1-b;3,4-b′]dithiophene (M2), respectively. It was deduced that P1 is a crystalline polymer while P2 is an amorphous one from the results of differential scanning calorimetry (DSC). Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra when dimethylsilyl substituents were introduced on the benzo[1,2-b;4,5-b′]dithiophene and benzo[2,1-b;3,4-b′]dithiophene skeletons. The fluorescence quantum yields (ΦFs) were not improved by the introduction of dimethylsilyl groups onto the benzo[1,2-b;4,5-b′]dithiophene and benzo[2,1-b;3,4-b′]dithiophene skeletons, whereas the improvement in the ΦFs was remarkable in the case of poly(tetramethylsilarylenesiloxane) derivatives that possessed the corresponding fused benzene ring systems, i.e., poly(tetramethyl-2,6-silanthrylenesiloxane) and poly(tetramethyl-1,8-silphenanthrylenesiloxane).
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Synthesis and properties of poly(tetramethyl-1,6-silpyrenylenesiloxane) derivative with phenyl groups on pyrenylene moiety
Polymer Bulletin, 2012Co-Authors: Kazutoshi Imai, Takumi Sasaki, Nobukatsu NemotoAbstract:Poly(tetramethyl-1,6-silpyrenylenesiloxane) derivative with phenyl groups on pyrenylene moieties ( P1 ) was prepared via polycondensation of Disilanol monomer, i.e. 1,6-bis(dimethylhydroxysilyl)-3,8-diphenylpyrene ( M1 ). P1 exhibited the very high glass transition temperature ( T _g) of 191 °C. The temperature at 5% weight loss ( T _d5) of P1 was 482 °C, indicating the relatively good thermostability of P1 . P1 exhibited the bathochromic effect in the absorption and fluorescence spectra, indicating the expansion of π-conjugation by introducing phenyl groups onto pyrene skeleton as well as the σ–π and σ*–π* conjugation between pyrene and silyl moieties. In addition, P1 exhibited relatively weak excimer emission because of the inhibition of the excimer formation of pyrene skeleton by introduction of bulky phenyl groups onto pyrene skeleton. The fluorescence quantum yields (Φ_Fs) of M1 and P1 in chloroform were determined to be 0.46 and 0.37, respectively. It was revealed that M1 and P1 exhibited the higher fluorescence intensity than 1,6-diphenylpyrene, owing to the effect of the introduction of silyl moieties onto pyrene skeleton.
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Synthesis and properties of cyclopentadithiophene-based poly(silarylenesiloxane) derivatives
Polymer, 2011Co-Authors: Hitoshi Hanamura, Nobukatsu NemotoAbstract:Abstract Poly(silarylenesiloxane) derivatives with 4,4-dimethylcyclopenta[2,1- b :3,4- b ′]dithiophene moiety, bearing dimethyl- ( P1 ), methylphenyl- ( P2 ) and diphenyl- ( P3 ) substituents on silyl moieties, were prepared via polycondensation of the corresponding Disilanol monomers, that is, 2,6-bis(dimethylhydroxysilyl)-4,4-dimethylcyclopenta[2,1- b :3,4- b ′]dithiophene ( M1 ), 2,6-bis(methylphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1- b :3,4- b ′]dithiophene ( M2 ), and 2,6-bis(diphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1- b :3,4- b ′]dithiophene ( M3 ), respectively. P1 – P3 exhibited the good solubility in common organic solvents, such as benzene, toluene, chloroform, dichloromethane, THF, and so on. The glass transition temperatures ( T g s) of P1 , P2 and P3 were determined by differential scanning calorimetry to be 56, 97 and 137 °C, respectively, depending on the substituent on the silyl moieties. No melting temperatures ( T m s) of P1 , P2 and P3 were observed, suggesting the obtained P1 – P3 are amorphous polymers. The temperatures at 5% weight loss ( T d5 s) of P1 , P2 and P3 were 460, 459 and 479 °C, respectively, indicating that the larger number of phenyl group on the silyl moieties resulted in the better thermostability. Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra by introducing silyl substituents onto 4,4-dimethylcyclopenta[2,1- b :3,4- b ′]dithiophene moiety. In addition, the bathochromic shift of the maximum absorption ( λ abs ) and the increase in the fluorescence quantum yield ( Φ F ) were observed by the introduction of phenyl group onto the silyl moieties.
Girish Mehta - One of the best experts on this subject based on the ideXlab platform.
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synthesis and catalytic studies of ti anchored Disilanol isobutyl poss alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Bialek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Synthesis and catalytic studies of Ti-anchored Disilanol isobutyl-POSS/alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Białek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Catalytic ethylene polymerization by the titanium-polyhedral oligomeric silsesquioxane-Et3Al2Cl3 system
Reaction Kinetics Mechanisms and Catalysis, 2011Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Girish MehtaAbstract:Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) trisilanol and Disilanol were prepared and characterized. These catalysts, formulated as [Ti-POSS(O∩O∩O)OPri, 1] and [Ti-(POSS(O∩O))2, 2], were found to be active in the polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as a co-catalyst. The polyethylene products so obtained are linear, crystalline and display narrow dispersities. The effect of various reaction parameters on the catalyst performance is described.
Akshay Mehta - One of the best experts on this subject based on the ideXlab platform.
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synthesis and catalytic studies of ti anchored Disilanol isobutyl poss alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Bialek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Synthesis and catalytic studies of Ti-anchored Disilanol isobutyl-POSS/alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Białek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Catalytic ethylene polymerization by the titanium-polyhedral oligomeric silsesquioxane-Et3Al2Cl3 system
Reaction Kinetics Mechanisms and Catalysis, 2011Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Girish MehtaAbstract:Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) trisilanol and Disilanol were prepared and characterized. These catalysts, formulated as [Ti-POSS(O∩O∩O)OPri, 1] and [Ti-(POSS(O∩O))2, 2], were found to be active in the polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as a co-catalyst. The polyethylene products so obtained are linear, crystalline and display narrow dispersities. The effect of various reaction parameters on the catalyst performance is described.
Gopal L. Tembe - One of the best experts on this subject based on the ideXlab platform.
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synthesis and catalytic studies of ti anchored Disilanol isobutyl poss alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Bialek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Synthesis and catalytic studies of Ti-anchored Disilanol isobutyl-POSS/alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Białek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Catalytic ethylene polymerization by the titanium-polyhedral oligomeric silsesquioxane-Et_3Al_2Cl_3 system
Reaction Kinetics Mechanisms and Catalysis, 2011Co-Authors: Akshay M. Mehta, Gopal L. Tembe, Parimal A. Parikh, Girish N. MehtaAbstract:Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) trisilanol and Disilanol were prepared and characterized. These catalysts, formulated as [Ti-POSS(O^∩O^∩O)OPr^ i , 1 ] and [Ti-(POSS(O^∩O))_2, 2 ], were found to be active in the polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et_3Al_2Cl_3) as a co-catalyst. The polyethylene products so obtained are linear, crystalline and display narrow dispersities. The effect of various reaction parameters on the catalyst performance is described.
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Catalytic ethylene polymerization by the titanium-polyhedral oligomeric silsesquioxane-Et3Al2Cl3 system
Reaction Kinetics Mechanisms and Catalysis, 2011Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Girish MehtaAbstract:Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) trisilanol and Disilanol were prepared and characterized. These catalysts, formulated as [Ti-POSS(O∩O∩O)OPri, 1] and [Ti-(POSS(O∩O))2, 2], were found to be active in the polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as a co-catalyst. The polyethylene products so obtained are linear, crystalline and display narrow dispersities. The effect of various reaction parameters on the catalyst performance is described.
Parimal A. Parikh - One of the best experts on this subject based on the ideXlab platform.
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synthesis and catalytic studies of ti anchored Disilanol isobutyl poss alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Bialek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Synthesis and catalytic studies of Ti-anchored Disilanol isobutyl-POSS/alkylaluminum system
Journal of Molecular Catalysis A-chemical, 2012Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Marzena Białek, Girish MehtaAbstract:Abstract Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) Disilanol were prepared and characterized. These catalysts formulated as [Ti(O^O)2] and [M(O^O)XCl] are found to be active in polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co-catalyst. The polyethylene product so obtained is linear, crystalline and displays narrow dispersities. The unique low molecular weight PE formed in this reaction exhibit properties that have potential industrial applications. The effect of various reaction parameters on catalyst performance is described.
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Catalytic ethylene polymerization by the titanium-polyhedral oligomeric silsesquioxane-Et_3Al_2Cl_3 system
Reaction Kinetics Mechanisms and Catalysis, 2011Co-Authors: Akshay M. Mehta, Gopal L. Tembe, Parimal A. Parikh, Girish N. MehtaAbstract:Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) trisilanol and Disilanol were prepared and characterized. These catalysts, formulated as [Ti-POSS(O^∩O^∩O)OPr^ i , 1 ] and [Ti-(POSS(O^∩O))_2, 2 ], were found to be active in the polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et_3Al_2Cl_3) as a co-catalyst. The polyethylene products so obtained are linear, crystalline and display narrow dispersities. The effect of various reaction parameters on the catalyst performance is described.
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Catalytic ethylene polymerization by the titanium-polyhedral oligomeric silsesquioxane-Et3Al2Cl3 system
Reaction Kinetics Mechanisms and Catalysis, 2011Co-Authors: Akshay Mehta, Gopal L. Tembe, Parimal A. Parikh, Girish MehtaAbstract:Titanium (IV) precursors anchored to alkyl substituted polyhedral oligomeric silsesquioxane (POSS) trisilanol and Disilanol were prepared and characterized. These catalysts, formulated as [Ti-POSS(O∩O∩O)OPri, 1] and [Ti-(POSS(O∩O))2, 2], were found to be active in the polymerization of ethylene at high temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as a co-catalyst. The polyethylene products so obtained are linear, crystalline and display narrow dispersities. The effect of various reaction parameters on the catalyst performance is described.