Browsing by Author "Higashihara, Tomoya"

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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.
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).