Browsing by Author "Ishizone, Takashi"

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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).
Tailored Synthesis of Triblock Co- and Terpolymers Composed of Synthetically Difficult Sequence Orders by Combining Living Anionic Polymerization with Specially Designed Linking Reaction
(2016-03)
Matsuo, Yuri
;
Konno, Ryuji
;
Goseki, Raita
;
Ishizone, Takashi
;
Hirao, Akira
This study demonstrates the versatility and wider applicability of the recently developed methodology combining the living anionic polymerization with a specially designed linking reaction using the alpha-phenylacrylate (or benzyl bromide) function, allowing the synthesis of triblock co- and terpolymers, which are otherwise difficut to be obtained by sequential addition of monomers during a sequential polymerization approach. With this methodology using styrene and four para -substituted styrene derivatives with N-cyclohexylimine, 4-N,N -dimethyl-2-oxazoline, 2,6-di(tert-butyl)-4-methylphenyl ester, and nitrile, 12 polymers among the 16 possible triblock terpolymers and 6 triblock copolymers were successfully synthesized. Furthermore, the synthesis of two tetrablock quarterpolymers was achieved by the same linking methodology. The polymers synthesized in this study are all well-controlled in chain length, composition, which are difficult to be obtained by the sequential polymerization. In addition, they possess functional groups usable for the further modification and introduction of other functionalities.