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  2. 青木 大輔

青木 大輔

アオキ ダイスケ  (Daisuke Aoki)

基本情報

所属
千葉大学 大学院工学研究院 准教授
学位
博士（工学）(東京工業大学)
ORCID ID
 https://orcid.org/0000-0002-7272-0643
J-GLOBAL ID
201801020964389097
researchmap会員ID
B000300505

研究分野

 1

論文

 112
  • Hiroki Sato, Daisuke Aoki, Toshikazu Takata
    ACS Macro Letters 5(6) 699-703 2016年6月  査読有り
    The synthesis of an ABC star terpolymer containing one polymer chain connected mechanically through a rotaxane linkage and its topology transformation to a linear structure are reported. Pseudo[2]-rotaxane, which was designed as the key trifunctional species for the star polymer synthesis, comprised a sec-ammonium axle with ethynyl and hydroxy groups and a crown ether wheel with a trithiocarbonate group. Stepwise polymer connections to the pseudo[2]rotaxane using the three groups afforded a rotaxane-linked ABC star terpolymer. The topology transformation from star to linear by the removal of the attractive interaction between the axle and wheel components yielded a linear ABC terpolymer via the wheel shifting to the axle end. The spectroscopic and solution property changes clearly indicated the occurrence of the polymer topology change.
  • Stephanie Valentina, Takahiro Ogawa, Kazuko Nakazono, Daisuke Aoki, Toshikazu Takata
    Chemistry - A European Journal 22(26) 8759-8762 2016年5月  査読有り
    High-yielding synthesis of cyclic block copolymer (CBC) using the rotaxane protocol by linear-cyclic polymer topology transformation was first demonstrated. Initial complexation of OH-terminated sec-ammonium salt and a crown ether was followed by the successive living ring-opening polymerizations of two lactones to a linear block copolymer having a rotaxane structure by the final capping of the propagation end. CBC was obtained in a high yield by an exploitation of the mechanical linkage through the translational movement of the rotaxane component to transform polymer structure from linear to cyclic. Furthermore, the change of the polymer topology was translated into a macroscopic change in crystallinity of the block copolymer.
  • Keisuke Iijima, Daisuke Aoki, Hiromitsu Sogawa, Shigeo Asai, Toshikazu Takata
    Polym. Chem. 7(21) 3492-3495 2016年  査読有り
    Vinylic supramolecular cross-linkers (VSCs) were prepared by mixing an alpha-cyclodextrin dimer or a trimer and a polyethylene glycol-type macromonomer. DOSY NMR study exhibited the size of VSC and its dependency on the concentration and the structure of the components. Polymerization of a vinyl monomer with VSC afforded rotaxane cross-linked polymers.
  • Zhen Chen, Daisuke Aoki, Satoshi Uchida, Hironori Marubayashi, Shuichi Nojima, Toshikazu Takata
    Angewandte Chemie International Edition 55(8) 2778-2781 2016年1月  査読有り
    Macromolecular [2] rotaxanes comprising a polymer axle and crown ether wheel were synthesized to evaluate the effect of component mobility on the properties of the axle polymer, especially its crystallinity. Living ring-opening polymerization of delta-valerolactone with a pseudorotaxane initiator with a hydroxy group at the axle terminus was followed by end-capping with a bulky isocyanate. This yielded macromolecular [2] rotaxanes (M2Rs) possessing polyester axles of varying molecular weights. The crystallinity of the axle polymers of two series of M2Rs, with either fixed and movable components, was evaluated by differential scanning calorimetry. The results revealed that the effect of component mobility was significant in the fixed and movable M2Rs with a certain axle length, thus suggesting that the properties of the axle polymer depend on the mobility of the polyrotaxane components.
  • Zhen Chen, Daisuke Aoki, Satoshi Uchida, Hironori Marubayashi, Shuichi Nojima, Toshikazu Takata
    Angewandte Chemie 128(8) 2828-2831 2016年1月  査読有り
  • Kazuhiko Yamada, Daisuke Aoki, Kentaro Kitagawa, Toshikazu Takata
    Chemical Physics Letters 630 86-90 2015年6月  査読有り
    Frequency-swept solid-state S-33 nuclear magnetic resonance (NMR) spectra of a S-33-enriched organosulfur compound, [S-33]-diphenyl disulfide, are presented. The NMR spectra were acquired at extremely low magnetic fields, 0.06 and 0.10 T, which correspond to Larmor frequencies of 0.1959 and 0.3265 MHz, respectively. The quadrupole coupling constant, C-Q, and the asymmetry parameter, eta(Q), for [S-33]-diphenyl disulfide were found to be C-Q = 43.3 +/- 1.9 MHz and eta(Q) = 0.70 +/- 0.20, respectively. T-1 measurements of [S-33]-diphenyl disulfide were performed between 60 and 300 K using nuclear quadrupole resonance signals, and a compromise observation temperature was found to be 300 K. Quantum chemical calculations were performed and the results demonstrated that the quadrupole frequencies and C-Q values were highly sensitive to the changes in dihedral angles of disulfide bonds. (C) 2015 Elsevier B.V. All rights reserved.
  • Daisuke Aoki, Satoshi Uchida, Toshikazu Takata
    Angewandte Chemie International Edition 54(23) 6770-6774 2015年4月  査読有り
    Topology transformation of a star polymer to a linear polymer is demonstrated for the first time. A three-armed star polymer possessing a mechanical linking of two polymer chains was synthesized by the living ring-opening polymerization of -valerolactone initiated by a pseudo[2]rotaxane having three hydroxy groups as the initiator sites on the wheel component and at both axle termini. The polymerization was followed by the propagation end-capping reaction with a bulky isocyanate not only to prevent the wheel component deslippage but also to introduce the urethane moiety at the axle terminal. The resulting rotaxane-linked star polymer with a fixed rotaxane linkage based on the ammonium/crown ether interaction was subjected to N-acetylation of the ammonium moiety, which liberated the components from the interaction to move the wheel component to the urethane terminal as the interaction site, eventually affording the linear polymer. The physical property change caused by the present topology transformation was confirmed by the hydrodynamic volume and viscosity.
  • Takahiro Ogawa, Kazuko Nakazono, Daisuke Aoki, Satoshi Uchida, Toshikazu Takata
    ACS Macro Letters 4(4) 343-347 2015年4月  査読有り
    We report a convenient and scalable synthesis of cyclic poly(epsilon-caprolactone) (PCL) from its linear counterpart based on the rotaxane protocol. Cyclic PCL was prepared by ring-opening polymerization of epsilon-caprolactone (epsilon-CL) initiated by a pseudo[2]rotaxane initiator in the presence of diphenylphosphate (DPP) as a catalyst, followed by capping of the propagation end by using a bulky isocyanate to afford macromolecular [2]rotaxane. The successive intramolecular cyclization to macromolecular [1]rotaxane at the polymer terminus proceeded with good yield. The attractive interaction of the terminal ammonium/crown ether moiety was removed via N-acetylation. This enabled movement of the crown ether wheel along the axle PCL chain to the urethane region of the other terminus in solution state. Size-exclusion chromatography and 2D diffusion-ordered spectroscopy (DOSY) results demonstrated the formation of cyclic PCL from linear PCL, which is further supported by thermal property or crystallinity change before and after transformation.
  • Sawada, J., Aoki, D., Uchida, S., Otsuka, H., Takata, T.
    ACS Macro Letters 4(5) 598-601 2015年  査読有り
    Macromolecular rotaxane cross-linkers having two radically polyrnerizable vinyl groups (RCs) were first synthesized and used to prepare network polymers. A crown ether/sec-ammonium-type pseudorotaxane initiator having an OH terminal-containing axle and a crown ether wheel with a vinyl group was subjected to the living ring-opening polymerization of delta-valerolactone followed by end-capping with a bulky isocyanate to yield a polyester axle-tethering macromolecular [2]rotaxane cross-linker (RC). Rotaxane cross-linked polymers (RCPs) were prepared by the radical polymerization of n-butyl acrylate in the presence of RCs (0.25, 0.50 mol %). The properties of the RCPs and covalently cross-linked polymers (CCPs) were characterized mainly by mechanical properties. Both fracture stress and strain values of RCPs were much higher than those of CCPs, probably owing to the increased network homogeneity by the rotaxane cross-link. The hybrid-type RCPs obtained from a mixture of RC and covalently connected cross-linker (CC) showed poorer mechanical properties similar to that of CCPs, indicating the importance of RCs in increasing the toughness of the network polymers.
  • Daisuke Aoki, Satoshi Uchida, Toshikazu Takata
    Polymer Journal 46(9) 546-552 2014年5月  査読有り
    A shape-transformable polymer in which the wheel component can move freely along the axle chain was synthesized and characterized. Rotaxane-linked linear poly(delta-valerolactone) was synthesized in one pot via ring-opening polymerization initiated by a sec-ammonium/crown ether-type pseudo[2]rotaxane that possessed two initiating hydroxyl groups on both the axle and wheel components; this was followed by an end-capping reaction with a bulky isocyanate. Acetylation of the obtained polymer to remove the interaction between the sec-ammonium axle and the crown ether wheel afforded the transformable polymer. The movement of the wheel component bearing a polymer chain was confirmed by weakening the interaction between the axle and the wheel in the rotaxane-linked linear polymer that did not possess a bulky end-cap group. The result clearly supported the mobility of the wheel component bearing a graft chain from one end of the polymeric axle chain to the other end.
  • Daisuke Aoki, Satoshi Uchida, Toshikazu Takata
    ACS Macro Letters 3(4) 324-328 2014年4月  査読有り
    An effective method to synthesize mechanically linked transformable block polymer was developed utilizing functional macromolecular [2]rotaxane with a "fixed" or "movable" wheel. The interaction between a sec-ammonium and a dibenzo-24-crown-8-ether was the key to control the mobility of the wheel component, indicating the capability of the transformation from linear block copolymer to block/graft copolymer in which the grafting polymer chain is movable along the axle polymer chain.
  • Daisuke Aoki, Satoshi Uchida, Kazuko Nakazono, Yasuhito Koyama, Toshikazu Takata
    ACS Macro Letters 2(6) 461-465 2013年6月  査読有り
    Macromolecular [2]rotaxanes, which consist of a polymer chain threading into a wheel component, were synthesized in high yield and with high purity. The synthesis was achieved by the ring-opening polymerization (ROP) of delta-valerolactone (VL) using a hydroxyl-terminated pseudorotaxane as an initiator with diphenyl phosphate as a catalyst in dichloromethane at room temperature. The H-1 NMR, gel permeation chromatography (GPC), and MALDI-TOF-MS measurements of the resulting poly(delta-valerolactone)s clearly indicate the presence of the rotaxane structure with the polymer chain, confirming that the diphenyl phosphate-catalyzed ROP of VL proceeds without deslippage of the wheel component. The obtained macromolecular [2]rotaxane was acetylated to afford a nonionic macromolecular [2]rotaxane, in which only one wheel component is movable from one end to another along the polymer chain.

MISC

 16
  • 鈴木大介, 高田十志和, 青木大輔
    『動的秩序と機能』ニュースレター 51 1 2017年11月  
  • 鈴木大介, 高田十志和, 青木大輔
    『動的秩序と機能』ニュースレター 46 3 2017年6月  
  • 高田 十志和, 青木 大輔
    高分子 = High polymers, Japan : polymers 66(5) 217-219 2017年5月  
  • 水野舜也, 曽川洋光, 青木大輔, 山本浩司, 高田十志和
    日本化学会春季年会講演予稿集(CD-ROM) 97th 2017年  
  • 青木 大輔, 高田 十志和
    日本ゴム協会誌 90(6) 283-289 2017年  
    <p>This review summarizes the development of stimuli-responsive materials based on the topology transformable polymers from branched to linear. The junction point of the rotaxane components bearing plural polymer chains is the key for the topology transformation which cannot be attained by the fixed junction point formed by the covalent bond. Crown ether-containing macromolecular [2]rotaxane with both ammonium and urethane moieties (M2R) as the stations for the crown ether wheel on the axle polymer chain produces the controllable and movable junction point of the polymer chains via the control of the component interaction, which enables the construction of sophisticated dynamic polymer systems. The rotaxane-linked star polymers with a fixed rotaxane linkage owing to the ammonium/crown ether interaction were synthesized by the introduction of two additional polymer chains to the components of M2R. The star polymers altered their topology to linear by the <i>N</i>-acetylation of the ammonium moiety, which broke the ammonium/crown ether interaction and generated the urethane/crown ether interaction to move the wheel component to the polymer chain terminal, eventually affording the linear polymer. The change in physical property caused by the topology transformation was confirmed in hydrodynamic volume and viscosity, demonstrating an effective way to the development of novel stimuli-responsive materials.</p>
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