Browsing by Author "Ito, Shotaro"

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Facile synthesis of multiarmed and multicomponent star polymers by a new iterative methodology using (formyl-protected 1,3-dioxolane)-end-functionalized polymer anions
(2016)
Goseki, Raita
;
Ito, Shotaro
;
Akemine, Emi
;
Hirao, Akira
;
應用化學系
A new and efficient iterative methodology using (formyl-protected 1,3-dioxolane (DOL))-end-functionalized polymer anions was carried out for the facile synthesis of multiarmed and multicomponent mu-star polymers. Using this methodology, both the arm introduction and DOL reintroduction steps are simultaneously performed by the linking reaction of the DOL-end-functionalized polymer anion with the formyl group regenerated from the DOL reintroduced in advance and repeated several times. By combining the DOL-end-functionalized polymer anions with non-DOL-functionalized polymer anions in the linking reaction, synthetically-difficult and well-defined complex mu-star polymers ranging from the ABC, ABCD, ABCDE, and ABCD(2), to the ABCD(2)E(2) types were successfully obtained. Moreover, synthesis of A(3)B(2) and A(3)B(2)C(4) star polymers was also achieved with the same methodology using (DOL)(2)-end-functionalized polymer anions. The arm segments were polystyrene, polystyrene derivatives, polyisoprene, poly(2-vinylpyridine), and poly(alkyl methacrylate(s)), which were introduced into the mu-star polymers via the formyl or alpha-phenylacrylate reaction site(s).
Precise Synthesis of Macromolecular Architectures by Novel Iterative Methodology Combining Living Anionic Polymerization with Specially Designed Linking Chemistry
(2017-10-01)
Goseki, Raita
;
Ito, Shotaro
;
Matsuo, Yuri
;
Higashihara, Tomoya
;
Hirao, Akira
This article reviews the development of a novel all-around iterative methodology combining living anionic polymerization with specially designed linking chemistry for macromolecular architecture syntheses. The methodology is designed in such a way that the same reaction site is always regenerated after the polymer chain is introduced in each reaction sequence, and this polymer chain introduction and regeneration of the same reaction site sequence is repeatable. Accordingly, the polymer chain can be successively and, in principle, limitlessly introduced to construct macromolecular architectures. With this iterative methodology, a variety of synthetically difficult macromolecular architectures, i.e., multicomponent -star polymers, high generation dendrimer-like hyperbranched polymers, exactly defined graft polymers, and multiblock polymers having more than three blocks, were successfully synthesized.
Precise Synthesis of New Exactly Defined Graft Copolymers Made up of Poly(alkyl methacrylate)s by Iterative Methodology Using Living Anionic Polymerization
(2015-11-24)
Ito, Shotaro
;
Ishizone, Takashi
;
Hirao, Akira
;
應用化學系
;
Department of Applied Chemistry
An iterative methodology using living anionic polymerization with a 1,1-diphenylethylene disubstituted with trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBS) ethers has been developed in order to synthesize new exactly defined graft copolymers made up of poly(alkyl methacrylate)s. During each reaction sequence, the TMS and TBS ethers were transformed into alpha-phenyl acrylate (PA) functions one by one at the different reaction stages. The first PA function derived from the TMS ether was utilized to introduce the graft chain, while the main chain with the TMS and TBS ethers was introduced via the second PA function derived from the TBS ether. Thus, the same chain-end functionalities (both TMS and TBS ethers) were reintroduced after construction of the graft unit. In practice, the reaction sequence involving "the introduction of the graft chain" and "the introduction of the main chain with the two silyl ethers" was iterated three times, leading to the synthesis of poly(benzyl methacrylate) (PBnMA)-exact graft-poly(methyl methacrylate) (PMMA) with three PMMA graft chains. Similarly, the synthesis of PBnMA-exact graft-poly(2-vinylpyridine) (P2VP) with two P2VP graft chains was successfully carried out. With the use of the alpha,omega-chain-end-difunctionalized PBnMA as the starting material, two graft units could be constructed at the same time by iterating the reaction sequence once. The graft copolymers with up to six graft chains were obtained by only three repeated reaction sequences. Thus, the reaction steps could be significantly reduced. The graft copolymers synthesized in this study were perfectly controlled in structure from a viewpoint of the following three parameters defining the structure of the graft copolymer: (1) molecular weight of the main chain, (2) molecular weights of the graft chains, and (3) number and placement of the graft chains. Furthermore, these three parameters can also be intentionally changed as required.
Syntheses of exactly-defined multi-graft polymers with two or more graft chains per branch point by a new iterative methodology
(2016)
Ito, Shotaro
;
Senda, Saeko
;
Ishizone, Takashi
;
Hirao, Akira
;
應用化學系
A new iterative methodology based on living anionic polymerization using a difunctional 1,1-diphenyl-ethylene derivative has been developed for the synthesis of exactly-defined graft polymers with two graft chains per branch point. In this methodology, a living polystyrene (PS)-b-poly(methyl methacrylate) (PMMA) in-chain-functionalized with trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBS) ethers was utilized as a building block, and the TMS and TBS ethers are sequentially converted to alpha-phenylacrylate (PA) reaction sites one by one. In each reaction sequence, the first PA group was utilized to introduce a poly ((2-methoxyethoxy) ethyl methacrylate) (PME2MA) as the second graft chain, while the building block was reintroduced via the second PA group. Since the two ethers were thus reintroduced after the construction of one graft unit, the same reaction sequence is repeated. In practice, an exactly-defined graft terpolymer with two different graft chains (PS and PME2MA segments) per branch point was successfully synthesized. The graft structure was perfectly controlled with respect to the following three parameters which define the structure of the graft polymer: (1) molecular weight of the main chain, (2) molecular weights of the graft chains, and (3) the position and number of the graft chains. More importantly, such parameters can be individually changed based on one\'s preference. Furthermore, structurally analogous multi-graft polymers with three or four different graft chains per branch point were also successfully synthesized by the linking reaction of a PMMA-exact graft-PS possessing three PA reaction sites with a diblock copolymer in-chain anion or a 3-armed mu-star polymer core anion.
Synthesis and Characterization of Multicomponent ABC- and ABCD-Type Miktoarm Star-Branched Polymers Containing a Poly(3-hexylthiophene) Segment
(2016-05)
Higashihara, Tomoya
;
Ito, Shotaro
;
Fukuta, Seijiro
;
Miyane, Satoshi
;
Ochiai, Yuto
The new series of ABC-type miktoarm star polymer (ABC star, A = polyisoprene (PI), B = polystyrene (PS), and C = poly(3-hexylthiophene) (P3HT)) and ABCDtype miktoarm star polymer (ABCD star, A = PI, B = PS, C = poly(alpha-methylstyrene) (P alpha MS), and D = P3HT) could be synthesized by the combination of the controlled KCTP, anionic linking reaction, and Click chemistry. By the copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition click reaction of the azido-chain-end-functional P3HT (P3HT-N-3) with the alkyne-in-chain-functional AB diblock copolymer (A = PI and B = PS) (AB-alkyne) or alkyne-core-functional ABC miktoarm star polymer (A = PI, B = PS, and C = P alpha MS) (ABC-alkyne), the target ABC star and ABCD star, respectively, were obtained, as confirmed by size exclusion chromatography (SEC) and proton nuclear magnetic resonance (H-1 NMR). The thermal and optical properties of these star polymers were examined by thermal gravimetric analysis (TGA) and UV-vis spectroscopy. The dynamic scattering calorimetry (DSC), atomic force micrograph (AFM) image, and grazing incidence small angle X-ray scattering (GISAXS) results showed that the periodic P3HT fibril nanostructures rather than microphase separation occurred in the ABCD star film. In addition, it was found that highly crystalline P3HT domains aligned in the "edge-on" orientation, as supported by grazing incidence wide-angle X-ray scattering (GIWAXS).
Synthesis of multicomponent asymmetric star-branched polymers by iterative methodology with new diblock copolymer in-chain anions as building blocks
(2017-08-25)
Goseki, Raita
;
Ito, Shotaro
;
Hirao, Akira
;
應用化學系
;
Department of Applied Chemistry
New AB diblock copolymer in-chain anions having poly(2-vinylpyridine) (P2VP) and/or poly(methyl methacrylate) (PMMA) blocks, whose anion is located at the junction between the A and B blocks, have been prepared by the 1:1 addition reaction of the living polymer (A) with the omega- or alpha-terminal 1-phenyl1-( 2-pyridinyl) ethylene-functionalized polymer (B). The P2VP-block-PS, PS-block-P2VP, P2VP-blockpoly( 4-tert-butyldimethylsilyloxystyrene), PS-block-PMMA, and P2VP-block-PMMA in-chain anions could be practically prepared for the first time. Based on this preparation, a newly synthesized 1,4-bis(1-(2pyridinyl) ethenyl) benzene satisfactorily works as a key core agent, with which the polymers (A) can be connected to the polymer (B), and the in-chain anion can be generated between the A and B polymers. By developing the iterative methodology with such new block copolymer in-chain anions as the building blocks, the successive synthesis of the 3-arm ABC and 5-arm ABCDE mu-star polymers having PMMA and P2VP arms, which were synthetically difficult by the previous systems, have been successfully achieved. The success of the developed methodology demonstrates the further possibility to synthesize more component mu-star polymers. (C) 2017 Elsevier Ltd. All rights reserved.