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Conformation and dynamics of conjugated polymers: A single-molecule study

Research Project

Project/Area Number 18340123
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Biophysics/Chemical physics
Research InstitutionTokyo Institute of Technology

Principal Investigator

VACHA Martin  Tokyo Institute of Technology, Graduate School of Science and Technology, Assoc. Professor (50361746)

Project Period (FY) 2006 – 2007
Project Status Completed (Fiscal Year 2007)
Budget Amount *help
¥13,440,000 (Direct Cost: ¥13,200,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥12,400,000 (Direct Cost: ¥12,400,000)
KeywordsSingle-molecule detection / Conjugated polymers / Polymer conformation
Research Abstract

We use single-molecule spectroscopy to study the conformation and related photophysics of the conjugated polymer MEH-PPV dispersed in spin-coated thin-film matrices. The conformation is measured via the polymer chain absorption anisotropy (absorption ellipsoid ratio r) using a novel fluorescence microscopic method. The method is based on alternative excitation of the sample with far-field epi-fluorescence and near-field total internal reflection modes. Polarization modulated fluorescence from individual molecules is fitted with theoretical expressions to obtain the shape and orientation of the absorption ellipsoid for each chain. A coarse-grain molecular dynamics (MD) is further used to simulate the actual conformations corresponding to the measured absorption ellipsoids. We found that MEH-PPV individual chains can attain a single form of a collapsed conformation in poor-solvent matrices (Zeonex), or can coexist in two forms of extended conformations in good-solvent matrices (PS). The … More MD simulations completely reproduce the experimental results when the factors of solvent, chemical defects and spin-coating conditions are included. The defect cylinder conformation observed in Zeonex explains the photophysical properties of emission intermittency and fluorescence spectra distributions. The two defect-coil-type conformations observed in PS correspond well with the two types of intermittency behavior and with the bi-modal spectral distributions observed. Moment analysis of the MD simulation results provides a link between the two conformation forms and the different photophysical properties. The work on MEH-PPV is further complemented by the study of a graft copolymer consisting of a polythiophene backbone and polystyrene branches. The presence of the branches prevents the molecule from forming a collapsed globule-like conformation. Polythiophenes with grafted PS branches (PT-PS) and without the branches (PT-R) show markedly different photophysical properties. Emission intensity of the PT-PS molecules decays gradually due to photobleaching. In PT-R the emission intensity oscillates between the background and one intensity level before one-step photobleaching takes place. The blinking and bleaching behavior of the PT-R polymer is due to the fact that emission of the chain proceeds from one or a few conjugated segments where the energy is quickly localized after absorption. The continuous decrease of emission intensity in case of PT-PS is a result of each segment emitting independently. The emission properties of the two polymers are further characterized by measuring the single molecule emission anisotropy ratio, the histogram of which shows a peak at 0 anisotropy for PT-PS and minimum at 0 for PT-R, and by studying the time-evolution of fluorescence spectra of individual molecules. Less

Report

(3 results)
  • 2007 Annual Research Report   Final Research Report Summary
  • 2006 Annual Research Report
  • Research Products

    (18 results)

All 2008 2007

All Journal Article (4 results) (of which Peer Reviewed: 3 results) Presentation (14 results)

  • [Journal Article] Relating Conformation and Photophysics in Single MEH-PPV Chains.2008

    • Author(s)
      Y. Ebihara, M. Vacha
    • Journal Title

      J. Phys. Chetn. B 112

      Pages: 12575-12578

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
    • Peer Reviewed
  • [Journal Article] Relating Conformation and Photophysics in Single MEH-PPV Chains.2008

    • Author(s)
      Y. Ebihara, M. Vacha
    • Journal Title

      J. Phys. Chem. B 112

      Pages: 12575-12578

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Journal Article] Structure dependent photophysics studied in single molecules of polythiophene derivatives.2007

    • Author(s)
      T. Sugimoto, Y. Ebihara, K. Ogino, M. Vacha
    • Journal Title

      ChemPhysChem 8

      Pages: 1623-1628

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
    • Peer Reviewed
  • [Journal Article] Structure dependent photophysics studied in single molecules of poly-thiophene derivatives.2007

    • Author(s)
      T. Sugimoto, Y. Ebihara, K. Ogino and M. Vacha
    • Journal Title

      ChemPhysChem 8

      Pages: 1623-1628

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Presentation] Confonnation and photophysics related in single chains of conjugated polymers (Invited).2008

    • Author(s)
      M. Vacha
    • Organizer
      3^<rd> International Symposium on Integrated Molecular/Materials Engineering
    • Place of Presentation
      西安、中国
    • Year and Date
      2008-11-07
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Conformation and photophysics related in single chains of conjugated polymers (Invited).2008

    • Author(s)
      M. Vacha
    • Organizer
      3^<rd> InternationalSymposium on Integrated Molecular/Ma terials Engineering
    • Place of Presentation
      Xi'an, China
    • Year and Date
      2008-11-07
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Conformation and related photophysics of single conjugated polymer chains in thin-film matrices.2008

    • Author(s)
      M. Vacha, Y. Ebihara
    • Organizer
      15^<th> International Conference on Luminescence
    • Place of Presentation
      リヨン、フランス
    • Year and Date
      2008-07-11
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Conformation and related photophysics of single conjugated polymer chains in thin-film matrices.2008

    • Author(s)
      M. Vacha, Y. Ebihara
    • Organizer
      15^<th> International Conference on Luminescence
    • Place of Presentation
      Lyon, France
    • Year and Date
      2008-07-11
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Conjugated Polymer Conformations and Related Photophysics in Thin-film Matrices : A Single Molecule study (Invited)2008

    • Author(s)
      M. Vacha, Y. Ebihara
    • Organizer
      1^<st> International Conference on Science and Technology of Solid Surfaces and Interfaces
    • Place of Presentation
      千葉
    • Year and Date
      2008-05-30
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Conjugated Polymer Conformations and Related Photophysics in Thin-film Matrices : A Single Molecule Study (Invited)2008

    • Author(s)
      M. Vacha, Y. Ebihara
    • Organizer
      1^<st> International Conference on Science and Technology of Solid Surfaces and Interfaces
    • Place of Presentation
      Chiba, Japan
    • Year and Date
      2008-05-30
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Relationship between conformation and photophysics of single chains of conjugated polymers2007

    • Author(s)
      M. Vacha
    • Organizer
      10^<th> Pacific Polymer Conference
    • Place of Presentation
      神戸
    • Year and Date
      2007-12-06
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Relationship between conformation and photophysics of single chains of conjugated polymers.2007

    • Author(s)
      M. Vacha
    • Organizer
      10^<th> Pacific Polymer Conference
    • Place of Presentation
      Kobe, Japan
    • Year and Date
      2007-12-06
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Relationship between conformation and photophysics of single chains of cojugated polymers2007

    • Author(s)
      VACHA Martin
    • Organizer
      10th Pacific Polymer Conference
    • Place of Presentation
      神戸
    • Year and Date
      2007-12-06
    • Related Report
      2007 Annual Research Report
  • [Presentation] ポリチオフェン単一分子鎖の構造と光物理的特性の相関2007

    • Author(s)
      VACHA Martin
    • Organizer
      2007光化学討論会
    • Place of Presentation
      松本
    • Year and Date
      2007-09-28
    • Related Report
      2007 Annual Research Report
  • [Presentation] 共役系高分子単一分子鎖の構造と光物理的特性の相関2007

    • Author(s)
      VACHA Martin
    • Organizer
      第56回高分子討論会
    • Place of Presentation
      名古屋
    • Year and Date
      2007-09-20
    • Related Report
      2007 Annual Research Report
  • [Presentation] Conformation and photophysical properties of single conjugated polymer molecules2007

    • Author(s)
      M. Vacha
    • Organizer
      XXIII International Conference on Photochemistry
    • Place of Presentation
      ケルン、ドイツ
    • Year and Date
      2007-08-02
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Conformation and photophysical properties of single conjugated polymer molecules studied via their absorption ellipsoids.2007

    • Author(s)
      M. Vacha
    • Organizer
      XXIII International Conference on Photochemistry
    • Place of Presentation
      Koln, Germany
    • Year and Date
      2007-08-02
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Conformation and photophysical properties of single conjugated polymermolecules studied via their absorption ellipsoids2007

    • Author(s)
      VACHA Martin
    • Organizer
      XXIII International Conference on Photochemistry
    • Place of Presentation
      ケルン、ドイツ
    • Year and Date
      2007-08-02
    • Related Report
      2007 Annual Research Report

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Published: 2006-04-01   Modified: 2021-04-07  

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