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Chiaki Yoshikawa

MANA Scientist

Affiliation:


Educational & Research History

2007 - Present
Researcher, National Institute for Materials Science
2006 - 2007
Postdoctoral Fellow, Institute for Chemical Research, Kyoto University
2004 - 2006
A Research Fellow of the Japan Society for the Promotion of Science for Young Scientist
2002 - 2006
Ph.D., Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University
2000 - 2002
M.S., Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University
1996 - 2000
B.S., Industrial Chemistry, Faculty of Engineering, Kyoto University
1994 - 1996
B.S., Department of Electronics, Faculty of Engineering, Doshisha University (Left school before graduating)

Research Interests

  • Kinetic Study on Termination of Living Radical Polymerization:

As in free radical polymerization, the propagating species in living radical polymerization (LRP) is a free radical. Therefore, radical-radical bimolecular termination should unavoidably occur also in LRP and play an important role, giving unique features to its kinetics. This must also be the case with successful LRP systems producing low-polydispersity polymers. In spite of such theoretical considerations, termination in LRP was not correctly understood when she began to study LRP, because of the lack of direct experimental evidence. Thus she directly observed termination reactions in LRP by conducting a monomer-free model experiment and confirmed the occurrence of termination with the same rate constant kt in LRP as in FRP. Also she made quantitatively experimental tests of the kinetic theories on the polymerization rate and polydispersity for LRP.

  • Protein Repellency of Well-defined Well-controlled Concentrated Polymer Brushes obtained by Surface-Initiated Living Radical Polymerization:

Surface-initiated LRP provides a well-controlled well-defined polymer brush with high graft density, which is called a "concentrated" polymer brush. The graft density of the concentrated brush is more than one order of magnitude higher than that of the semi-dilute/dilute brushes obtained by conventional methods. In good solvent, this concentrated brush is highly stretched, nearly to their full length. Reflecting this stretched structure, this brush shows strong repulsion against compression and super-lubrication. Focusing on the unique high-extension structure of the concentrated brushes, she revealed the unique size-exclusion effect of the concentrated brushes, namely a good correlation between the protein size and the threshold graft density beyond which the protein does not adsorb. She also confirmed that the interaction of the concentrated PHEMA brush with proteins is very low at the outermost surface but significant inside. She successfully demonstrated that the concentrated brush exhibited excellent protein repellency due to the unique size-exclusion effect. The concentrated brush is believed to be a novel biocompatible surface.



Selected Papers

  1. Quantitative Comparison of Theory and Experiment on Living Radical Polymerization Kinetics. 1. Nitroxide-Mediated Polymerization
    Yoshikawa, C.; Goto, A.; Fukuda, T
    Macromolecules, 35, 2002, 5801-5807.
  2. Quantitative Comparison of Theory and Experiment on Living Radical Polymerization Kinetics. 2. Atom Transfer Radical Polymerization
    Yoshikawa, C.; Goto, A.; Fukuda, T
    Macromolecules, 36, 2003, 908-912.
  3. Protein Repellency of Well-defined, Concentrated Poly(2-hydroxyethyl methacrylate) Brushes by Size-Exclusion Effect
    Yoshikawa, C.; Goto, A.; Tsujii, Y.; Fukuda, T.; Kimura, T.; Yamamoto, K.; Kishida, A
    Macromolecules, 39, 2006, 2284-2290.
  4. Surface Interaction of Well-Defined, Concentrated Poly(2-hydroxyethyl methacrylate) with Proteins
    Yoshikawa, C.; Goto, A.; Ishizuka, N.; Nakanishi, K.; Tsujii, Y.; Fukuda, T.
    J. Polym.Sci.Part A., 45, 2007, 4795-4803.
  5. Size-Exclusion Effect and Protein Repellency of Concentrated Polymer Brushes Prepared by Surface-Initiated Living Radical Polymerization
    Yoshikawa, C.; Goto, A.; Ishizuka, N.; Nakanishi, K.; Kishida A.; Tsujii, Y.; Fukuda, T.
    Macromol.Symp., 248, 2007, 189-198.
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