Postdoctoral Associate

Office: 226 Mason Lab

Phone: (203) 436-4059
   

Since Feb 2015, Postdoctoral Fellow, Yale University, School of Engineering & Applied Science, Department of Chemical Engineering. ( JSPS Postdoctoral Fellow for Research Abroad )

Apr. 2013 - Jan. 2015: Postdoctoral researcher, Emergent Molecular Function Research Group, Center for Emergent Matter Science, RIKEN.

Mar. 2013: Ph.D. (Engineering) Institute of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba. ( JSPS Research Fellow: DC1 )

Mar. 2010: M.S. Institute of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba.

Mar. 2008: B.S. College of Engineering Sciences, University of Tsukuba.

Complete CV here

Personal Web Site here

In the Osuji lab, I am working on “Synthesis of self-assembled functional block copolymers and large are control of their nano -structures by magnetic alignment” Our group has shown that magnetic alignment is a promising way to control orientation of self-assembled nano -structures of block copolymers. This approach can be applied to many functional block polymers with appropriate molecular design. Particularly, applying this approach to block copolymers bearing optical and electronic functionalities is of great interest and importance for their device application.

Before joining the Osuji lab, I was working as a posdoc for two years at RIKEN (supervisor: Prof. Dr. Kazuo Takimiya , Dr. Itaru Osaka). My research there focused on the synthesis of solution-processable ambipolar semiconducting polymers and their device application to organic field-effect transistors (OFET). I developed a synthetic route to thienoquinoidal acceptor units, and investigated structure-property relationship of a series of semiconducting polymers incorporating the acceptor units. Some of the polymers exhibited well-balanced ambipolar charge transport in their OFET devices under ambient conditions, and exhibited one of the best switching characteristics in their organic complementary-like inverter devices (Figure 1, left). (Advanced Electronic Materials  2015, 1, 1500039, DOI : 10.1002/ aelm.201500039). These polymers have very small bandgaps (Eg < 1.2 eV), one of which with a π-extended quinoid has a bandgap of 0.88 eV and is almost transparent in visible region. Such transparent semiconducting polymers can be useful for next generation transparent electronics (Figure 1, right). (Journal of the American Chemical Society 2016, in press, DOI: 10.1021/jacs.6b03688).

 

Figure 1

March 2013, I obtained my Ph.D. in Engineering from University of Tsukuba under the supervision of Prof. Dr. Hiromasa Goto . My Ph.D. research concerned electrosynthesis of ordered and structured conjugated polymer materials, with a special focus on the relationship between molecular structures of monomers, polymerization conditions, nano -, micro-, and macro- scopic order and structure, and optical properties of corresponding polymers. In the research, I developed directed electropolymerization methods by using liquid crystal (LC) templates (Figure 2). For example, 1) uniaxially ordered conjugated polymer films was prepared by electropolymerization in a nematic LC oriented by rubbing technique ( Polymer Chemistry , 2010 , 1 , 1606-1608, DOI : 10.1039/ C0PY00279H ), 2) electrosynthesis of polythiophenes with controlled molecular orientation (vertical, horizontal, oblique) was demonstrated by using a smectic A LC solvent oriented with magnetic field (Figure 3) ( ACS Macro Lett er, 2013 , 2 , 587–591, DOI : 10.1021/ mz400213k ), 3) helically-aggregated optically active conjugated polymer films were prepared by using cholesteric LC solvents ( Macromolecules , 2013 , 46 , 2078–2091, DOI : 10.1021/ ma400302j ). I also worked on electrosynthesis of electroactive conjugated polymer nanofibers ( Chemistry - A European Journal , 2012 , 18 , 15065-15072, DOI : 10.1002/ chem.201201471).

 

Figure 2: LC-directed electropolymerization

 

Figure 3: Polythiophene films electrodeposited in magnetically aligned (left: vertical, right: horizontal) SmA LC solvents.

  1. Kohsuke Kawabata* ; Masahiko Saito; Itaru Osaka*; Kazuo Takimiya, Very Small Bandgap π-Conjugated Polymers with Extended Thienoquinoids. Journal of the American Chemical Society 2016, in press. DOI : 10.1021/jacs.6b03688
  2. Hiroki Hayashi; Kohsuke Kawabata ; Shigeki Nimori; Hiromasa Goto*, A Poly(ter(3,4-ethylenedioxythiophene)) Showing Concentric-Circle Morphology Prepared by Electrochemical Synthesis in Smectic A Liquid Crystal under Vertical Strong Magnetic Field. Chemistry Letters 2016, 45, (2), 170-172. DOI : org/10.1246/cl.151066
  3. Hirotsugu Kawashima; Kohsuke Kawabata ; Aohan Wang; Hiromasa Goto*, Synthesis and optical properties of poly(phenylenethiophene)s bearing conjugated side chains. Designed Monomers and Polymers 2015, 18, (7), 661-668. DOI : 10.1080/15685551.2015.1070498
  4. Kohsuke Kawabata ; Itaru Osaka*; Masahiro Nakano; Noriko Takemura ; Tomoyuki Koganezawa ; Kazuo Takimiya , Thienothiophene-2,5-Dione-Based Donor-Acceptor Polymers: Improved Synthesis and Influence of the Donor Units on Ambipolar Charge Transport Properties. Advanced Electronic Materials 2015 , 1, (6), 150039. DOI : 10.1002/ aelm.201500039
  5. Atsushi Matsumura; Kohsuke Kawabata ; Hiromasa Goto* , Synthesis, Properties, and Doping Behavior of Optically Active Polythiophenes Bearing a Bornyl Group. Macromolecular Chemistry and Physics 2015 , 216, (9), 931-938. DOI : 10.1002/ macp.201400594
  6. Aohan Wang; Kohsuke Kawabata ; Hiromasa Goto* , Thiophene-based chiral small bandgap pi-conjugated polymers: synthesis and optical properties. Designed Monomers and Polymers 2015, 18, (4), 360-366. DOI : 10.1080/15685551.2015.1012625
  7. Hirotsugu Kawashima; Kohsuke Kawabata ; Hiromasa Goto* , Intramolecular charge transfer (ICT) of a chiroptically active conjugated polymer showing green colour . Journal of Materials Chemistry C 2015, 3, (5), 1126-1133. DOI : 10.1039/ C4TC02124J
  8. Jiuchao Dong; Kohsuke Kawabata ; Hiromasa Goto* , Synthesis and characterization of a novel donor-acceptor- donor chiral inducer and its application in electrochemical polymerization. Journal of Materials Chemistry C 2015, 3, (9), 2024-2032. DOI : 10.1039/ C4TC02489C
  9. Kuniharu Nakajima; Kohsuke Kawabata ; Hiromasa Goto* , Water soluble polyaniline/polysaccharide composite: Polymerization, carbonization to yield carbon micro-bubbles. Synthetic Metals 2014, 194, 47-51. DOI : 10.1016/ j.synthmet.2014.04.015
  10. Tomokazu Iseki; Kohsuke Kawabata ; Shigeki Nimori ; Hiromasa Goto* , Synthesis of chiral inducers having double stereogenic centers for electrochemical polymerization in cholesteric liquid crystal medium. Synthetic Metals 2014, 187, 217-223. DOI : 10.1016/ j.synthmet.2013.11.017
  11. Tomokazu Iseki; Kohsuke Kawabata ; Hirotsugu Kawashima; Hiromasa Goto* , Catalysis direction selective asymmetric polymerization in chiral liquid crystal medium. Polymer 2014, 55, (1), 66-72. DOI : 10.1016/ j.polymer.2013.12.009
  12. Kohsuke Kawabata ; Shigeki Nimori ; Hiromasa Goto* , Horizontal and Vertical Orientation of Polythiophenes by Electrochemical Polymerization in Magnetically Aligned Smectic Liquid Crystal. ACS Macro Letters 2013, 2, (7), 587-591. DOI : 10.1021/ mz400213k
  13. Kohsuke Kawabata ; Masaki Takeguch ; Hiromasa Goto* , Optical Activity of Heteroaromatic Conjugated Polymer Films Prepared by Asymmetric Electrochemical Polymerization in Cholesteric Liquid Crystals: Structural Function for Chiral Induction. Macromolecules 2013, 46, (6), 2078-2091. DOI : 10.1021/ ma400302j
  14. Aohan Wang; Kohsuke Kawabata ; Hirotsugu Kawashima; Hiromasa Goto* , Synthesis of a pyrimidine-based new chiral inducer for construction of cholesteric liquid crystal electrolyte solution and its electrochemical polymerization, and stimulated emission like interference. Polymer 2013, 54, (15), 3821-3827. DOI : 10.1016/ j.polymer.2013.04.053
  15. Aohan Wang; Kohsuke Kawabata ; Hiromasa Goto* , Synthesis of Isothianaphthene ( ITN ) and 3,4- Ethylenedioxy -Thiophene ( EDOT )-Based Low-Bandgap Liquid Crystalline Conjugated Polymers. Materials 2013, 6, (6), 2218-2228. DOI : 10.3390/ ma6062218
  16. Satoshi Ohkawa ; Fan Yang; Kohsuke Kawabata ; Hiromasa Goto* , Synthesis of polymers from chiral monomers in chiral liquid crystals. Journal of Applied Polymer Science 2013, 128, (6), 3586-3591. DOI : 10.1002/ app.38561
  17. Hitoshi Hayashi; Aohan Wang; Kohsuke Kawabata ; Hiromasa Goto* , Helical twisting power of three-ring chiral molecules and polymerization in cholesteric electrolyte solutions. Materials Chemistry and Physics 2013, 137, (3), 816-824. DOI : 10.1016/ j.matchemphys.2012.10.017
  18. Hiromasa Goto* ; Atsushi Yokoo ; Masaki Takeguchi ; Kohsuke Kawabata , Small Carbon Forms From Polyaniline/Metal. International Journal of Polymeric Materials and Polymeric Biomaterials 2013, 62, (8), 426-432. DOI : 10.1080/00914037.2012.721412
  19. Hiromasa Goto* ; Aohan Wang; Shigeki Nimori ; Kohsuke Kawabata , Mechanical orientation in thermotropic liquid crystal state and magnetic orientation in solvent evaporation process via lyotropic liquid crystal state of an amphotropic low-bandgap liquid-crystalline -conjugated polymer. Liquid Crystals 2013, 40, (9), 1159-1166. DOI : 10.1080/02678292.2013.818168
  20. Hiromasa Goto* ; Aohan Wang; Kohsuke Kawabata ; Fan Yang, Synthesis and properties of a low-bandgap liquid crystalline pi-conjugated polymer. Journal of Materials Science 2013, 48, (21), 7523-7532. DOI : 10.1007/ s10853 -013-7567-3
  21. Hiromasa Goto* ; Kohsuke Kawabata , Preparation of Phenylenevinylene Derivatives Having Fluorescence and Chiral Induction Function. Journal of Dispersion Science and Technology 2013, 34, (3), 311-321. DOI : 10.1080/01932691.2012.666139
  22. Jiuchao Dong; Kohsuke Kawabata ; Takahiro Seino; Fan Yang; Hiromasa Goto* , Synthesis and characterisation of thieno [3,2-b]thiophene-based linear shaped liquid crystals. Liquid Crystals 2013, 40, (11), 1455-1465. DOI : 10.1080/02678292.2013.835453
  23. Kohsuke Kawabata ; Hiromasa Goto* , Dynamically Controllable Emission of Polymer Nanofibers: Electrofluorescence Chromism and Polarized Emission of Polycarbazole Derivatives. Chemistry-A European Journal 2012, 18, (47), 15065-15072. DOI : 10.1002/ chem.201201471
  24. Kohsuke Kawabata ; Hiromasa Goto* , Synthesis and optical properties of 1,1- binaphthyl -thiophene alternating copolymers with main chain chirality. Journal of Materials Chemistry 2012, 22, (44), 23514-23524. DOI : 10.1039/ C2JM35594A
  25. Hirotsugu Kawashima; Kohsuke Kawabata ; Hiromasa Goto* , Synthesis and double doping behavior of a poly(p- phenylenevinylene )s bearing conjugated side chains. Journal of Polymer Science Part A-Polymer Chemistry 2012, 50, (8), 1530-1538. DOI : 10.1002/ pola.25919
  26. Yu Innami ; Rafael H. L. Kiebooms ; Tamotsu Koyano ; Masaaki Ichinohe; Satoshi Ohkawa ; Kohsuke Kawabata ; Masataka Kawamatsu ; Kiyoto Matsuishi ; Hiromasa Goto* , Synthesis of a low-bandgap polymer bearing side groups containing phenoxy radicals. Journal of Materials Science 2011, 46, (20), 6556-6562. DOI : 10.1007/ s10853 -011-5602-9
  27. Hiromasa Goto* ; Kohsuke Kawabata , Light driven asymmetric polymerization: an approach for tele-control reaction. Polymer Chemistry 2011, 2, (5), 1098-1106. DOI : 10.1039/ C0PY00396D
  28. Satoshi Ohkawa ; Reina Ohta ; Kohsuke Kawabata ; Hiromasa Goto* , Polymerization in Liquid Crystal Medium: Preparation of Polythiophene Derivatives Bearing a Bulky Pyrimidine Substituent. Polymers 2010, 2, (4), 393-406. DOI : 10.3390/ polym2040393
  29. Kohsuke Kawabata ; Hiroyuki Yoneyama ; Hiromasa Goto* , Uniaxially ordered conjugated polymer film prepared by electrochemical polymerization in a nematic liquid crystal with rubbing orientation method showing redox-driven tunable dichroism. Polymer Chemistry 2010, 1, (10), 1606-1608. DOI : 10.1039/ C0PY00279H
  30. Kohsuke Kawabata ; Hiromasa Goto* , Electrosynthesis of 2,7-linked polycarbazole derivatives to realize low-bandgap electroactive polymers. Synthetic Metals 2010, 160, (21-22), 2290-2298. DOI : 10.1016/ j.synthmet.2010.08.023
  31. Hiromasa Goto* ; Yong-Soo Jeong ; Kohsuke Kawabata ; Masaki Takada; Takuya Kotanagi ; Hideyuki Shigemori ; Nobuhiko Nomura, Electrochemical preparation of an electroactive polymer poly( dodecyloxy dibenzothiophene ) ( polyDDBTh ) from hydroxyl dibenzothiophene ( HDBTh ) as a bioconverted monomer. Journal of Applied Electrochemistry 2010, 40, (1), 191-195. DOI : 10.1007/ s10800 -009-9994-z
  32. Kohsuke Kawabata ; Hiroyuki Yoneyama ; Hiromasa Goto* , Preparation of Furan-Based Monomers and Asymmetric Electrochemical Polymerization in Cholesteric Liquid Crystals: Optical Activity and Selective Reflection. Molecular Crystals and Liquid Crystals 2009, 515, 3-15. DOI : 10.1080/15421400902987636
  33. Kohsuke Kawabata ; Hiromasa Goto* , Liquid Crystalline pi-Conjugated Copolymers Bearing a Pyrimidine Type Mesogenic Group. Materials 2009, 2, (1), 22-37. DOI : 10.3390/ ma2010022
  34. Kohsuke Kawabata ; Hiromasa Goto* , Periodic Structure in a Fluorene -based Polymer Prepared by Electrochemical Polymerization. Chemistry Letters 2009, 38, (7), 706-707. DOI : 10.1246/ cl.2009.706
  35. Hiroyuki Yoneyama ; Kohsuke Kawabata ; Akitsu Tsujimoto ; Hiromasa Goto* , Preparation of iridescent-reflective poly(furan-co- phenylene )s by electrochemical polymerization in a cholesteric liquid crystal medium. Electrochemistry Communications 2008, 10, (7), 965-969. DOI : 10.1016/ j.elecom.2008.04.021
  36. Hiromasa Goto* ; Fumihiro Togashi ; Akitsu Tsujimoto ; Reina Ohta ; Kohsuke Kawabata , Cholesteric liquid crystal inductive asymmetric polymerisation of thiophene monomers. Liquid Crystals 2008, 35, (7), 847-856. DOI : 10.1080/02678290802227276
  37. Hiromasa Goto* ; Kohsuke Kawabata , Visualization of nematic liquid crystal director by alignment of pi-conjugated polymer nanotubes. Macromolecules 2008, 41, (13), 4551-4554. DOI : 10.1021/ ma800455v