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Tsuyoshi Michinobu - One of the best experts on this subject based on the ideXlab platform.

  • Sequentially Different AB Diblock and ABA Triblock Copolymers as P3HT:PCBM Interfacial Compatibilizers for Bulk-Heterojunction Photovoltaics
    2016
    Co-Authors: Hiroyuki Fujita, Tsuyoshi Michinobu, Seijiro Fukuta, Tomoyuki Koganezawa, Tomoya Higashihara
    Abstract:

    The P3HT:PCBM (P3HT = poly­(3-hexylthiophene, PCBM = phenyl-C61-butyric acid methyl ester) bulk-heterojunction (BHJ) organic photovoltaic (OPV) cells using the AB diblock and ABA triblock copolymers (A = Polystyrene Derivative with donor–acceptor units (PTCNE) and B = P3HT) as compatibilizers were fabricated. Under the optimized blend ratio of the block copolymer, the power conversion efficiency (PCE) was enhanced. This PCE enhancement was clearly related to the increased short-circuit current (Jsc) and fill factor (FF). The incident photon to current efficiency (IPCE) measurement suggested that the P3HT crystallinity was improved upon addition of the block copolymers. The increased P3HT crystallinity was consistent with the increased photovoltaic parameters, such as Jsc, FF, and consequently the PCE. The surface energies of these block copolymers suggested their thermodynamically stable location at the interface of P3HT:PCBM, showing the efficient compatibilizing performance, resulting in enlarging and fixing the interfacial area and suppressing the recombination of the generated carriers. Grazing incidence X-ray scattering (GIXS) results confirmed the superior compatibilizing performance of the ABA triblock copolymer when compared to the AB diblock copolymer by the fact that, after blending the ABA triblock copolymer in the P3HT:PCBM system, the enhanced crystallinity of matrix P3HT was observed in the excluded areas of the less-aggregated PCBM domains, changing the P3HT crystalline domain orientation from “edge-on” to “isotropic”. This is, to the best of our knowledge, the first sequential effect (AB vs ABA) of the block copolymers on the compatibilizing performances based on BHJ OPV device systems

  • colorimetric sensing of cations and anions by clicked Polystyrenes bearing side chain donor acceptor chromophores
    Polymer Chemistry, 2012
    Co-Authors: Minoru Ashizawa, Tsuyoshi Michinobu, Satoshi Uchida
    Abstract:

    Donor–acceptor chromophores were introduced into the side chains of a Polystyrene Derivative through the efficient click postfunctional addition reaction between dialkylaniline-activated alkynes and small acceptors, such as tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The resulting Polystyrenes were fully characterized by GPC, 1H NMR, IR spectroscopy, and elemental analysis. After the postfunctionalization, the polymers were highly colored due to the formed donor–acceptor chromophores in the side chains and these chromophores showed a colorimetric sensing behavior for some metal ions and anions. Some hard-to-borderline metal ions were always recognized by the dialkylanilino nitrogen atom, resulting in a decrease in the charge-transfer (CT) band intensity of the donor–acceptor chromophores. However, the recognition site of the soft Ag+ ion was the cyano nitrogen atoms due to readily formed multivalent coordination, leading to a bathochromic shift in the CT bands for both TCNE- and TCNQ-adducted polymers. This remarkable dual colorimetric detection of two different types of metal ions was achieved by the elegant design of polymeric chemosensors. On the other hand, it was found that the dicyanoethene moieties of the side chain chromophores serve as a chemodosimeter for some anions. For example, the CN− ion underwent a nucleophilic addition reaction to the electron-deficient ethene moieties, resulting in a dramatic decrease in the CT bands. All types of sensing behavior of both cations and anions were visually recognized. The use of small molecular model compounds enabled the estimation of the kinetic parameters and the product structures.

  • double click synthesis and second order nonlinearities of Polystyrenes bearing donor acceptor chromophores
    Macromolecules, 2010
    Co-Authors: Kazuma Tsuboi, Tsuyoshi Michinobu
    Abstract:

    Donor−acceptor chromophores were almost quantitatively introduced into the side chains of a Polystyrene Derivative by sequential “click chemistry”-type addition reactions as an efficient postfunctionalization method. The first click reaction is the conventional Cu(I)-catalyzed azide−alkyne cycloaddition (CuAAC), and the second one is the atom-economic addition of strong acceptor molecules, such as tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ), to the aniline-substituted electron-rich alkynes. Steric hindrance was found to be an important factor in determining the reactivity of alkyne-acceptor addition reactions. All obtained polymers showed good solubility in common organic solvents, and they were fully characterized by GPC, 1H NMR and IR spectroscopy, and elemental analysis. After the acceptor addition, the polymers showed an intense charge-transfer (CT) band centered at ca. 480 nm for the TCNE adducts and ca. 710 nm for the TCNQ adducts. Electrochemical measurements of these poly...

Nakano Tamaki - One of the best experts on this subject based on the ideXlab platform.

  • Photo-induced helix-helix transition of a Polystyrene Derivative
    polymer chemistry, 2014
    Co-Authors: Wang Yue, Sakamoto Takeshi, Koyama Yasuhito, Takanashi Yuma, Kumaki Jiro, Cui Jiaxi, Wan Xinhua, Nakano Tamaki
    Abstract:

    Poly(2,5-bis[4-((S)-2-methylbutyloxy)phenyl]styrene) having a helical conformation underwent helix-helix transition upon photo-irradiation. Conformational transition can significantly alter polymer properties, and so far thermal stereomutation has been studied. However, as for photo-induced mutation, only helix-helix transition (irreversible CD-active to CD-silent helix transition) of a polyacrylate has been explored. Here, we present mutation of the Polystyrene Derivative. Chiroptical, viscometric, and vibrational spectroscopic analyses indicated the polymer mutated from an optically active helix to another optically inactive helix with a different shape.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000330154600009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Polymer ScienceSCI(E)EI12ARTICLEtamaki.nakano@cat.hokudai.ac.jp3718-721

Tamaki Nakano - One of the best experts on this subject based on the ideXlab platform.

  • photo induced helix helix transition of a Polystyrene Derivative
    Polymer Chemistry, 2014
    Co-Authors: Yue Wang, Takeshi Sakamoto, Yasuhito Koyama, Yuma Takanashi, Jiro Kumaki, Jiaxi Cui, Xinhua Wan, Tamaki Nakano
    Abstract:

    Poly(2,5-bis[4-((S)-2-methylbutyloxy)phenyl]styrene) having a helical conformation underwent helix–helix transition upon photo-irradiation. Conformational transition can significantly alter polymer properties, and so far thermal stereomutation has been studied. However, as for photo-induced mutation, only helix–helix transition (irreversible CD-active to CD-silent helix transition) of a polyacrylate has been explored. Here, we present mutation of the Polystyrene Derivative. Chiroptical, viscometric, and vibrational spectroscopic analyses indicated the polymer mutated from an optically active helix to another optically inactive helix with a different shape.

Takeshi Endo - One of the best experts on this subject based on the ideXlab platform.

  • Reversible Fixation and Release of Alcohols by a Polymer Bearing Vicinal Tricarbonyl Moieties and Its Application to Synthesis and Reversible Cross-Linking–De-Cross-Linking System of a Networked Polymer
    2016
    Co-Authors: Kazuhide Morino, Atsushi Sudo, Takeshi Endo
    Abstract:

    In this paper, we report reversible fixation and release of alcohols by a Polystyrene Derivative bearing acyclic vicinal tricarbonyl moieties (1) and its application to synthesis and reversible cross-linking-de-cross-linking system of a networked polymer. First the reversible fixation and release behavior of alcohols by an acyclic vicinal tricarbonyl compound, 1,3-diphenylpropanetrione (DPPT) as a model compound of 1 was investigated. On the basis of the results, the fixation of n-hexanol to 1 was carried out to provide the n-hexanol adduct of 1 (1-HexOH), which has a hemiacetal structure. On the other hand, heating 1-HexOH in vacuo enabled successful recovery of 1 to demonstrate the reversible nature of this system. Furthermore, the reaction of 1 with 1,6-hexanediol proceeded smoothly to give networked polymer, which could be de-cross-linked by heating at 50 °C in DMSO/H2O mixture. This result indicates that a novel reversible cross-linking–de-cross-linking system of networked polymer was constructed

  • reversible cross linking and de cross linking system of Polystyrenes bearing the monohydrate structure of vicinal tricarbonyl group through water alcohol exchange reactions at ambient conditions
    Macromolecules, 2012
    Co-Authors: Morio Yonekawa, Yoshio Furusho, Takeshi Endo
    Abstract:

    We describe in this paper reversible cross-linking and de-cross-linking system based on a Polystyrene Derivative bearing monohydrate structure of vicinal tricarbonyl groups with 1,6-hexanediol utilizing the direct water–alcohol exchange reactions on the vicinal tricarbonyl groups. By employing diphenylpropanetrione as a unit model compound for the polymer, we have demonstrated that the water–alcohol exchange reactions could be carried out reversibly in both directions by changing solvents. Notably, the water–alcohol exchange reactions proceeded without any catalysts and under mild conditions. For example, an equimolar mixture of the hydrate of diphenylpropanetrione and benzyl alcohol in chloroform (0.5 M) reached equilibrium after standing at ambient temperature within 48 h, where the content ratio of the benzyl alcohol adduct increased up to 49%. The reaction rate and the position of the equilibrium were highly affected by the concentrations of the substrates as well as the reaction temperature. By virtu...

  • Reversible Cross-Linking and De-Cross-Linking System of Polystyrenes Bearing the Monohydrate Structure of Vicinal Tricarbonyl Group through Water–Alcohol Exchange Reactions at Ambient Conditions
    2012
    Co-Authors: Morio Yonekawa, Yoshio Furusho, Takeshi Endo
    Abstract:

    We describe in this paper reversible cross-linking and de-cross-linking system based on a Polystyrene Derivative bearing monohydrate structure of vicinal tricarbonyl groups with 1,6-hexanediol utilizing the direct water–alcohol exchange reactions on the vicinal tricarbonyl groups. By employing diphenylpropanetrione as a unit model compound for the polymer, we have demonstrated that the water–alcohol exchange reactions could be carried out reversibly in both directions by changing solvents. Notably, the water–alcohol exchange reactions proceeded without any catalysts and under mild conditions. For example, an equimolar mixture of the hydrate of diphenylpropanetrione and benzyl alcohol in chloroform (0.5 M) reached equilibrium after standing at ambient temperature within 48 h, where the content ratio of the benzyl alcohol adduct increased up to 49%. The reaction rate and the position of the equilibrium were highly affected by the concentrations of the substrates as well as the reaction temperature. By virtue of the above characteristic features of the water–alcohol exchange reactions, the Polystyrene Derivative bearing monohydrate structure of vicinal tricarbonyl group (2.0 M) was cross-linked with 1,6-hexanediol (0.2 equiv of OH group to the tricarbonyl unit) in acetone at ambient temperature for 5 days to afford the networked polymer in almost quantitative yield. On the other hand, the networked polymer was treated with an excess of water at ambient temperature for 3 days to afford the original linear polymer in high yield as a result of de-cross-linking through the water–alcohol exchange reaction. The cross-linking and de-cross-linking behavior was also evidenced by SEC analysis of the reaction mixture

  • construction of reversible hydration dehydration system by a model compound and a novel polymer bearing vicinal tricarbonyl structure
    Journal of Polymer Science Part A, 2011
    Co-Authors: Takehito Dei, Kazuhide Morino, Atsushi Sudo, Takeshi Endo
    Abstract:

    A novel polymer bearing acyclic vicinal tricarbonyl moieties in the side chains was synthesized by (1) radical polymerization of a styrene Derivative with a 1,3-diketone structure and (2) successive treatment of the resulting Polystyrene Derivative by N-bromosuccinimide to convert its 1,3-diketone moiety in the side chains into the corresponding vicinal tricarbonyl moiety. The tricarbonyl moiety was highly reactive with water to permit its rapid conversion into a geminal diol structure in water-containing acetone. On the other hand, heating the resulting polymer bearing the geminal diol structure under vacuum enabled successful recovery of the vicinal tricarbonyl moiety to demonstrate the reversible nature of this system, which allowed us to repeat the hydration–dehydration cycle without deteriorating the polymer structure. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Eric Drockenmuller - One of the best experts on this subject based on the ideXlab platform.

  • Enhancing Properties of Anionic Poly(ionic liquid)s with 1,2,3-Triazolium Counter Cations
    ACS Macro Letters, 2014
    Co-Authors: Mona Obadia, Bhanu Prakash Mudraboyina, Anatoli Serghei, Didier Gigmes, Trang N.t. Phan, Eric Drockenmuller
    Abstract:

    A series of anionic poly(ionic liquid)s with 1,2,3-triazolium counter cations are prepared by cation exchange between tailormade 1,3,4-trialkylated-1,2,3-triazolium iodides and a Polystyrene Derivative having pendant potassium bis-(trifluoromethylsulfonyl)imide groups. The physical and ion-conducting properties of the resulting materials are compared to the parent potassium-containing polyelectrolyte based on H-1 NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and broadband dielectric spectroscopy (BDS) measurements. Substitution of the potassium counter cation by 1,2,3-triazolium charge carriers affords polyelectrolytes with improved processability (broader solubility and removal of the crystalline behavior) as well as a substantial increase in anhydrous ionic conductivity.