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KOHSAKA Yasuhiro

Academic OrganizationAcademic Assembly School of Science and Technology Institute of Textile Science and TechnologyTEL0268-21-5488
Education and Research OrganizationInterdisciplinary Cluster for Cutting Edge Research Research Initiative for Supra-MaterialsFAX
PositionAssociate ProfessorMail
Address3-15-1, Tokida, Ueda City 386-8567Web site


Assigned Class
Faculty of Textile Science and Technology Department of Chemistry and Materials Course of Functional Polymer Science
Research Group
Kohsaka Laboratory
Research Field
Polymer Synthesis
Keywords:Precise polymerization chemistry , Functional monomer , Degradable Polymer , Ring-opening polymerization (ROP) , Radical polymerization , Polycondensation , Chemical Recycle
Academic Societies
Academic Societies
Academic Background
Graduate School
Tokyo Institute of Technology , (Department of Organic and Polymeric Materials , 理工学研究科) , 2011
Tokyo Institute of Technology , (Department of Organic and Polymeric Materials , 理工学研究科) , 2008

Tokyo Institute of Technology , (Faculty of Engineering) , 2006

Doctor of Engineering , Tokyo Institute of Technology
2021 , Young Talents in Polymer Science
2018 , 日本化学会第98年次大会 優秀講演賞(学術)
2018 , Emerging Investigator 2018 , This is not a prize but honor
2015 , 宇部興産科学技術振興財団 第55回研究奨励賞
2009 , 第5回CERI最優秀発表論文賞
Research Career
Research Career
2011-2015 , Assistant ProfessorGraduate School of Engineering Science, Osaka University
2008-2011 , 日本学術振興会 特別研究院

Overseas Education
2009-2010 , Massachusetts Institute of Technology


Books, Articles, etc.
「クリックケミストリー ―基礎から実用まで―」 第15章 クリック反応性基を有するアクリル系ポリマーの精密合成と反応
シーエムシー出版 2014

Polyrtaxane Networks as a topologically cross-linked polymer: Synthesis and properties in Supramolecular Polymer Chemistry
Willey-VCH 2012
Author:Yasuhito Koyama, Takayuki Arai, Yasuhiro Kohsaka, Masahiro Shioya, Toshikazu Takata

High-Speed Synthesis of Thermo-responsive Polymers by Boosted Polymerization of N,N-Diethyl Acrylamide in High-Temperature Water
Industrial & Engineering Chemistry Research,61(46):17012-17016 2022(Nov. 09)
Author:Sumito Ishii, Akinori Sezai, Yasuhiro Kohsaka, Shigeru Deguchi, and Mitsumasa Osada

Diverse chemically recyclable polymers obtained by cationic vinyl and ring-opening polymerizations of the cyclic ketene acetal ester “dehydroaspirin”
Polymer Chemistry 2022(Oct. 17)
Author:Akane Kazama, Yasuhiro Kohsaka

アスピリンを原料とする循環型ポリマー -2つの重合様式による異種ポリマーの合成-
繊維学会誌,78(5):199-202 2022(May)
Author:Akane Kazama, Yasuhiro Kohsaka

繊維学会誌,78(3):111-115 2022(Mar.)
Author:高坂 泰弘,川谷 諒

(REVIEW) Polymer Chemistry of alpha-Substituted Acrylates Designed for Functional-Group Synergy
Journal of Macromolecular Science, Part A 2021(Oct. 13)
Author:Y. Kohsaka, Y. Akae, R. Kawatani, A. Kazama
Abstract:This article overviews the polymer chemistry of acrylates designed for functional-group synergy among the vinyl group and ester- and alpha-substituents. alpha-Substituents have been incorporated to tune the reactivity of the vinyl group; for example, ethyl alpha-cyanoacrylate, known as instant adhesions, has high reactivity to initiate anionic polymerization using moisture. Moreover, alpha-acyloxyacrylates undergo radical polymerization, increasing the degree of polymerization in proportion to monomer conversions due to the stabilized radical species by the captodative effect. alpha-Arylacrylates produced alternating copolymers with methyl methacrylate (MMA) using anionic polymerization, which exhibited specific fluorescence. alpha-(Aminomethyl)acrylates stabilized by intramolecular hydrogen bonding yielded a pH-/thermo-responsive polymer. Anionic polymerization of alpha-(alkoxymethyl)acrylates resulted in high isotacticity due to the chelating effect at the propagating chain end. alpha-(Halomethyl)acrylates underwent a nucleophilic conjugate substation reaction, applied to end-functionalization, polycondensation, and polymer degradation. For a long time, ring-opening polymerization of cyclic acrylates has been considered difficult; however, it was recently achieved using sophisticated monomer design.

Synthesis of polyarylates and aliphatic polyesters by divalent acyl-1,2,4-triazole: a route to metal-free synthesis at low temperature
Polymer Jouranl,53(8):887-893 2021(Apr. 20)
Author:Y. Kohsaka, I. Mori, K. Homma, Y. Akae, D. Matsuura, Y. Kimura
Abstract:Aromatic, semiaromatic, and aliphatic polyesters were synthesized at moderate temperatures (25–80 °C) by the polymerization of divalent acyl-1,2,4-triazoles using 4-(dimethylamino)pyridine as a catalyst. The monomers were prepared from divalent acyl chloride in high yields, although some of them required that toluene and pyridine be used as solvents due to their high crystallinity. Melt polymerization in diphenyl ether was effective in affording semiaromatic and aliphatic polyesters. However, this method was not suitable for aromatic polyesters, as the reaction system became heterogeneous at 80 °C. Nevertheless, solution and interfacial polymerization reactions were effective in obtaining aromatic polyesters. The novel monomers provided polyester synthesis at moderate temperature without the use of any metal catalyst or halide monomers.

Controls and Effects of Monomer Junctions and Sequences in Curable and Degradable Polyarylate Containing Acrylate Moieties
Macromol. Rapid Commun. 2021
Author:Y. Kohsaka, N. Nagai

Magnesium bromide (MgBr2) as a catalyst for living cationic polymerization and ring-expansion cationic polymerization"
Polym. Chem 2021
Author:Y. Daito, R. Kojima, N. Kusuyama, Y. Kohsaka, M. Ouchi

Synthesis of Poly(Conjugated Ester)s by Ring-Opening Polymerization of Cyclic Hemiacetal Ester Bearing Acryl Skeleton
European Polymer Journal,120:109185 2020
Author:Yasuhiro Kohsaka, Mai Yamashita, Yosuke Matsuhashi, Shuji Yamashita

End-reactive poly(tetrahydrofuran) for functionalization and graft copolymer synthesis via a conjugate substitution reaction
Polymer Journal,52:75 2020
Author:Yasuhiro Kohsaka, Naoki Nagatsuka

Divergence of polycondensation by a tandem reaction based on sequential conjugate substitutions
Polymer Chemistry,:5128 2020
Author:Keito Hagiwara, Yasuhiro Kohsaka

(FOCUS REVIEW) Conjugate substitution reaction of alpha-(substituted methyl)acrylates in polymer chemistry
Polymer Journal,52:1175 2020
Author:Yasuhiro Kohsaka

Degradable and curable poly(conjugated ester)s prepared by acryl- and conjugate-substitutions of the ‘smallest’ monomer
Eur. Polym. J.,141:110049 2020
Author:Y. Kohsaka, K. Nagai,

Radical Polymerization of Dehydroaspirin with a Formation of Hemiacetal Ester Skeleton: A Hint for Recyclable Vinyl Polymers
Polymer Chemistry,10:2764 2019
Author:Akane Kazama, Yasuhiro Kohsaka

Synthesis and properties of polyethers containing 1,3-butadiene skeleton in the backbones
Chemistry Letters,48(8):894 2019
Author:Yasuhiro Kohsaka, Akira HIramatsu

Esterification with Aromatic Acyl-1,2,4-triazole Catalyzed by Weak Base at the Rate Comparable to Acyl Chloride
CHEMISTRY LETTERS,47(1):100-102 2018
Author:Kohsaka, Yasuhiro; Homma, Kazumasa; Sugiyama, Susumu; Kimura, Yoshikazu;

Bifunctional Acyl-1,2,4-triazole: An Alternative Monomer of Dicarbonyl Chloride for Metal- and Halogen-free Polyester Synthesis
CHEMISTRY LETTERS,47(2):221-224 2018
Author:Kohsaka, Yasuhiro; Homma, Kazumasa; Mori, Ichiro; Sugiyama, Susumu; Kimura, Yoshikazu;

(INVITED) Conjugate substitution and addition of alpha-substituted acrylate: a highly efficient, facile, convenient, and versatile approach to fabricate degradable polymers by dynamic covalent chemistry
POLYMER CHEMISTRY,9(13):1610-1617 2018
Author:Kohsaka, Yasuhiro; Miyazaki, Takumi; Hagiwara, Keito;

マテリアルステージ,18(7):38-47 2018

機能材料,38(9):45-53 2018

日本ゴム協会誌,91(11) 2018

Synthesis of isotactic poly[alpha-(hydroxymethyl)acrylate] by anionic polymerization of the protected monomer
POLYMER BULLETIN,74(5):1935-1948 2017(May)
Author:Kohsaka, Yasuhiro; Yamamoto, Kazuki; Suzawa, Kazuha; Kitayama, Tatsuki;

Synthesis and reaction of block copolymer composed of independently clickable segments via monomer-selective living copolymerization
Author:Ladelta, Viko; Kohsaka, Yasuhiro; Kitayama, Tatsuki;

Polymerization of α-(Halomethyl)acrylates through Sequential Nucleophilic Attack of Dithiols using a Combination of Addition–Elimination and Click Reactions
Polym. Chem.,8:976-979 2017
Author:Yasuhiro Kohsaka, Keito Hagiwara, Keiichiro Ito

Polymerization of alpha-(halomethyl)acrylates through sequential nucleophilic attack of dithiols using a combination of addition-elimination and click reactions
POLYMER CHEMISTRY,8(6):976-979 2017
Author:Kohsaka, Yasuhiro; Hagiwara, Keito; Ito, Keiichiro;

Anionic polymerization of ethyl acrylate initiated by tetrabutylammonium azide: direct synthesis of end-clickable polyacrylate
POLYMER CHEMISTRY,8(26):3858-3861 2017
Author:Kataoka, Yuki; Kohsaka, Yasuhiro; Kitaura, Takehiro; Domae, Shogo; Ishihara, Shoya; Kitayama, Tatsuki;

Acid- or photo-cleavable polyrotaxane: Subdivision of supramolecular main-chain type polyrotaxane structure induced by acidolysis or photolysis
POLYMER,125:134-137 2017
Author:Araki, Jun; Honda, Yuta; Kohsaka, Yasuhiro;

α-Exomethylene lactone possessing acetal–ester linkage: Polymerization and postpolymerization modification for water-soluble polymer
Journal of Polymer Science Part A: Polymer Chemistry,54(7):955-961 2016
Author:Kohsaka, Y; Matsumoto, Y; Zhang, T; Matsuhashi, Y; Kitayama, T
Abstract:Spotlight Articleとして特別枠で収録

Synthesis of thermo-responsive polymer via radical (co)polymerization of N,N-dimethyl-α-(hydroxymethyl)acrylamide with N,N-diethylacrylamide
Polymers,8:374 2016
Author:Yasuhiro Kohsaka, Yoshiaki Tanimoto

(総説)α-機能化アクリル酸エステルの重合化学 —精密重合・機能創成を目指した分子設計—
高分子論文集,73(5):412-427 2016

Synthesis and post-polymerization reaction of end-clickable stereoregular polymethacrylates via termination of stereospecific living anionic polymerization
POLYMER CHEMISTRY,6(7):1078-1087 2015
Author:Kohsaka, Yasuhiro; Kurata, Takashi; Yamamoto, Kazuki; Ishihara, Shoya; Kitayama, Tatsuki;

Stereospecific Anionic Polymerization of α-(Hydroxymethyl)acrylate with Protective Group
Macromol. Symp.,350:86-98 2015
Author:Yasuhiro Kohsaka, Kazuha Suzawa, Tatsuki Kitayama

C60-Containing polymethacrylates: synthesis, properties, and potential application as n-type semiconductor for organic solar cell
Polym. Bull.,72:1265-1280 2015
Author:Viko Ladelta, Yasuhiro Kohsaka, Toshihiro Ohnishi, Michio Matsumura, Tatsuki Kitayama

Stereoregular poly(methyl methacrylate) with double-clickable omega-end: synthesis and click reaction
POLYMER CHEMISTRY,6(19):3601-3607 2015
Author:Kohsaka, Yasuhiro; Yamamoto, Kazuki; Kitayama, Tatsuki;

Termination of living anionic polymerization of butyl acrylate with α-(chloromethyl)acrylate for end-functionalization and application to the evaluation of monomer reactivity
Macromol. Chem. Phys.,216(14):1534-1539 2015
Author:Yasuhiro Kohsaka, Shoya Ishihara, Tatsuki Kitayama

alpha-(Aminomethyl)acrylate: Polymerization and spontaneous post-polymerization modification of beta-amino acid ester for pH- / temperature-responsive material
Polym. Chem.,6:5026-5029 2015
Author:Yasuhiro Kohsaka, Yusuke Matsumoto, Tatsuki Kitayama

高分子論文集,72(7):385-394 2015
Author:髙坂 泰弘; 北浦 健大; 北山 辰樹;
Keywords:Stereospecific Anionic Polymerization; End-Functionality; Telechelic Polymer; Functional Initiator; Functional Terminator; Click Reaction; Thiol-Ene Reaction; Azide-Alkyne Cycloaddition; Polymerization Reactivity of Monomers;

(総説)メタクリル酸メチルの精密アニオン重合 : 分子量,立体規則性,末端構造の三元同時制御
日本ゴム協会誌 = Journal of the Society of Rubber Science and Technology, Japan,88(3):80-85 2015
Author:髙坂 泰弘; 北山 辰樹;
Keywords:Living Anionic Ploymerization; Stereoregularity; End-functionalization; Stereospecific Polymerization; Tacticity; Click Chemistry;

Stimuli-degradable cross-linked polymers synthesized by radical polymerization using a size-complementary [3]rotaxane cross-linker
POLYMER JOURNAL,46(1):67-72 2014
Author:Iijima, Keisuke; Kohsaka, Yasuhiro; Koyama, Yasuhito; Nakazono, Kazuko; Uchida, Satoshi; Asai, Shigeo; Takata, Toshikazu;

Anionic Alternating Copolymerization of alpha-Arylacrylates with Methyl Methacrylate: Effect of Monomer Sequence on Fluorescence
Author:Kohsaka, Yasuhiro; Yamaguchi, Eiji; Kitayama, Tatsuki;

Photodegradable cross-linked polymer derived from a vinylic rotaxane cross-linker possessing aromatic disulfide axle
Author:Koyama, Yasuhito; Yoshii, Takahiro; Kohsaka, Yasuhiro; Takata, Toshikazu;

End-functional stereoregular poly(methyl methacrylate) with clickable C=C bonds: facile synthesis and thiol-ene reaction
POLYMER CHEMISTRY,4(19):5043-5047 2013
Author:Kohsaka, Yasuhiro; Kurata, Takashi; Kitayama, Tatsuki;

An efficient synthetic entry to rotaxanes utilising reversible cleavage of aromatic disulphide bonds
Author:Yoshii, Takahiro; Kohsaka, Yasuhiro; Moriyama, Taichi; Suzuki, Takao; Koyama, Yasuhito; Takata, Toshikazu;

Size-Complementary Rotaxane Cross-Linking for the Stabilization and Degradation of a Supramolecular Network
Author:Kohsaka, Yasuhiro; Nakazono, Kazuko; Koyama, Yasuhito; Asai, Shigeo; Takata, Toshikazu;

Graft Polyrotaxanes: A New Class of Graft Copolymers with Mobile Graft Chains
Author:Kohsaka, Yasuhiro; Koyama, Yasuhito; Takata, Toshikazu;

Main chain-type polyrotaxane with controlled ratio of rotaxanated units
CHEMISTRY LETTERS,36(2):292-293 2007
Author:Takata, Toshikazu; Kohsaka, Yasuhiro; Konishi, Gen-ichi;

接着学会関東支部 第20回 関東支部若手交流会 2021(Dec. 10)

高分子学会関東支部 第93回武蔵野地区高分子懇話会 2021(Dec. 02)

AREC 第12回産学交流ラウンジ 2021(Sep. 22)

第67回高分子研究発表会(神戸) 2021(Jul. 09)

高分子学会精密ネットワークポリマー研究会 第15回若手シンポジウム 2021(Mar. 15)

日本接着学会次世代接着材料研究会PartⅧ 第3回例会 2021(Feb. 03)

高分子学会 接着と塗装研究会/日本接着学会「2020年度接着と塗装研究会講座」 2019(Nov. 15)

Polymer Synthesis, Degradation, Functionalization and Transformation by Conjugate Substitution Reaction
S-Membrane International Conference 2019 (SMIC2019) 2019(Sep. 06)
Presenter:Yasuhiro Kohsaka

Chemoselective Degradable Polymer by Monomer Designing
International Symposium on Polymer Synthesis and Materials (PolySM) 2019(Sep. 04)
Presenter:Yasuhiro Kohsaka

機能高分子材料研究会 2019(Jul. 17)

Conjugate substitution: Robust Chemistry for Polymer Synthesis, Degradation and Main Chain Exchanges
The Polymer Society of Korea, 2019 Annual Spring Meeting”, Korea-Japan Joint Symposium: Fundamental Polymer Science for Future Technology 2019(Apr. 12)
Presenter:Yasuhiro Kohsaka

Designed Monomers for Polymers Leading Backbone Destruction and Reconstruction Reactions
The 99th Annual Meeting of The Chemical Society of Japan, Asian International Symposium - Polymer - 2019(Mar. 19)
Presenter:Yasuhiro Kohsaka

接着学会粘着研究会166回例会 2019(Mar. 08)

高分子学会Webinar 2018(Oct. 28)

Synthesis and Degradation of Polymers Prepared from Vinyl Monomers Bearing Cyclic Hemiacetal Ester Moieties
The 10th International Conference of Modification, Degradation, and Stabilization of Polymers (MoDeSt2018) 2018
Presenter:Yasuhiro Kohsaka

第67回高分子学会年次大会(招待講演) 2018

Synthesis of Poly(conjugated ester)s by Polycondensation and Ring-Opening Polymerization for Chemically Degradable Biocompatible Polymers
IUPAC Macro2018 2018
Presenter:Yasuhiro Kohsaka

Atropos Polymerization: Controlled Polymerization by Programmed Termination and Application Thereof
12th IUPAC International Conference on Ionic Polymerization (IP2017) 2017
Presenter:Yasuhiro Kohsaka

Polymer Synthesis by Tandem Reaction of α-(Halomethyl)acrylate via Addition-Fragmentation and Click Reactions
The 12th International Conference on Advanced Polymers via Macromolecular Engineering (APME 2017) 2017
Presenter:Yasuhiro Kohsaka, Keito Hagiwara, Takumi Miyazaki,

Polymer Synthesis by Conjugate Substitution of α-(Halomethyl)acrylate
日本ゴム協会 第28回エラストマー討論会(英語招待講演) 2017
Presenter:Yasuhiro Kohsaka

平成29年度日本化学会 東北支部秋田地区講演会 2017

Preparation of a ‘One-by-one Chain-Tethered’ type sliding graft copolymer
9th International Conference on Fiber and Polymer Biotechnology (IFPB2016) 2016
Presenter:Chihiro Otsubo, Yasuhiro Kohsaka, Jun Araki

Anionic Polymerization of Acrylates by Onium Salts with Aluminum Lewis Acid Activator
World Congress on Living Polymerizations and Polymers (LPP16) 2016
Presenter:Kentaro Shirota, Yusuke Kataoka, Shogo Domae, Takehiro Kitaura, Yasuhiro Kohsaka, Tatsuki Kitayama

Anionic cyclopolymerization of α-linked diacrylate
World Congress on Living Polymerizations and Polymers (LPP16) 2016
Presenter:Seungmin Choi, Nobuya Tanaka, Ren Sakamoto, Yasuhiro Kohsaka, Tatsuki Kitayama

Atropos Polymerization: Controlled Polymerization by Programmed Termination
World Congress on Living Polymerizations and Polymers (LPP16) 2016
Presenter:Yasuhiro Kohsaka, Tatsuki Kitayama

Polymerization of Protected 2-(Hydroxymethyl)acrylate and Insolubilization/Water-Solubilization by Acid-hydrolysis
Asian Conference on Adhesion 2016 (ACA2016) 2016
Presenter:Yasuhiro Kohsaka, Yusuke Matsumoto, Kazuki Yamamoto, Kazuha Suzawa, Tianyi Zhang, Yosuke Matsuhashi, Tatsuki Kitayama

One pot Synthesis of Stereoregular Graft Copolymer of Polymethacrylate One-pot synthesis of Stereoregular Graft Copolymer of Polymethacrylate via Selective Termination with Monomer-bearing Terminator via Selective Termination with Monomer-bearing Term
The 11th International Conference on Advanced Polymers via Macromolecular Engineering (APME 2014) 2015
Presenter:Shu Kano, Yasuhiro Kohsaka, Tatsuki Kitayama

Ring Opening Polymerization of β–butyrolactone by Onium Salts and Bulky Aluminum Phenoxide via O-Alkyl Scission Mechanism
The 11th International Conference on Advanced Polymers via Macromolecular Engineering (APME 2015) 2015
Presenter:Taka-aki Tanaka, Takehiro Kitaura, Yasuhiro Kohsaka, Tatsuki Kitayama

Precise synthesis of poly(methyl methacrylate): Controls of molecular weight, stereoregularity, and end-Functionality
International Conference on Smart Systems Engineering 2015 (SmaSys 2015) 2015
Presenter:Yasuhiro Kohsaka

Ethyl α-(aminomethyl)acrylate: An β-amino acid ester for pH/temperature-responsive polymers
The 11th International Conference on Advanced Polymers via Macromolecular Engineering (APME 2015) 2015
Presenter:Yasuhiro Kohsaka, Yusuke Matsumoto, Tatsuki Kitayama

Ethyl α-(aminomethyl)acrylate : An amphiphilic monomer for pH- Temperature-responsive Polymers
International symposium on Amphiphilic polymers, networks gels, and membranes (APNGM15) 2015
Presenter:Yasuhiro Kohsaka, Yusuke Matsumoto, Tatsuki Kitayama

End-clickable stereoregular poly(methyl methacrylate)s by termination of stereospecific anionic polymerization
nternational Science and Nature Congress (ISNaC) 2015 2015
Presenter:Yasuhiro Kohsaka

Atropos polymerization: Spontaneous controls of molecular weight and end-functionality via programmed termination
International Symposium on Ionic Polymerization 2015 (IP15’) 2015
Presenter:Yasuhiro Kohsaka, Shoya Ishihara, Tatsuki Kitayama

pH- / Temperature-responsive Materials Prepared from β-Amino Acid Ester Carrying Polymerizable Group
The 13 th Asian Textile Conference 2015
Presenter:Yasuhiro Kohsaka, Yusuke Matsumoto, Tatsuki Kitayama