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筋田 涼太*; 今井 彩帆里*; 大内 誠*; 青木 裕之; 寺島 崇矢*
Macromolecules, 56(23), p.9738 - 9749, 2023/12
被引用回数：0 パーセンタイル：0(Polymer Science)Constructing ordered ionic nanostructures into bulk polymers and thin films is an important technique to create functional materials, such as polyelectrolytes and proton- and ion-conducting materials, for various applications. Herein, we report microphase separation of cationic homopolymers bearing alkyl ammonium bromides to create sub-4 nm lamellar materials, where an ionic phase is alternatingly layered with a hydrophobic alkyl phase and serves as a channel for water intercalation. We prepared cationic homopolymers with linear or branched alkyl pendants (octyl or 2-ethylhexyl group: C8-eicosyl or 2-octyldodecyl group: C20) via the free radical polymerization of 2-(dimethylamino)ethyl acrylate (DMAEA), followed by the quaternization of the polyDMAEA with corresponding alkyl bromides. The homopolymers carrying linear hexadecyl, octadecyl, and eicosyl groups were crystalline at room temperature, whereas the others were amorphous. The homopolymers bearing linear alkyl pendants longer than the decyl group or branched alkyl pendants larger than the 2-butyloctyl group formed lamellar structures by the self-assembly of the side chains. The domain spacing can be controlled between 2.5 and 3.7 nm by tuning the pendant structures and are smaller than that formed by the corresponding random copolymers. A cationic homopolymer bearing crystalline octadecyl groups maintained lamellar structures up to 
210 
C far beyond the melting temperature (50 C). The cationic homopolymer further formed a multilayered lamellar thin film on a silicon substrate, in which the cationic layers absorbed water under humid conditions and reversibly released the water therefrom in a N
gas atmosphere.
Hibino, Masayuki*; 高田 慎一; 廣井 孝介; 青木 裕之; 寺島 崇矢*
Macromolecules, 56(8), p.2955 - 2964, 2023/04
被引用回数：0 パーセンタイル：0(Polymer Science)Amphiphilic random copolymers bearing poly(ethylene glycol) (PEG) and alkyl groups as side chains are intermolecularly self-assembled into size-controlled multichain micelles in water. The random copolymer micelles are known to induce the exchange of their polymer chains, whereas the details of the kinetics and mechanism have not been elucidated yet. Herein, we investigated the exchange kinetics and mechanism of the random copolymer chains between their micelles by time-resolved small-angle neutron scattering (TR-SANS). For this purpose, random copolymers carrying PEG and deuterated butyl or dodecyl groups were designed for deuterated micelles. After mixing deuterated and non-deuterated micelle solutions, the resulting mixtures were monitored by TR-SANS at various concentrations and temperatures. The scattering intensity of the micelle mixtures decayed with time, indicating that deuterated copolymers were gradually mixed with non-deuterated copolymers via chain exchange between their micelles to form micelles consisting of both deuterated and non-deuterated copolymers. The kinetic analysis revealed that the exchange of their polymer chains involved two mechanisms: A unimer release and insertion pathway was dominant in diluted conditions, whereas the contribution of a micelle collision pathway increased with increasing total polymer concentration and temperature. The activation energy of the polymer exchange process was dependent on the hydrophobic alkyl groups and larger than that of a related surfactant micelle.
今井 彩帆里*; 荒川 勝利*; 中西 洋平*; 竹中 幹人*; 青木 裕之; 大内 誠*; 寺島 崇矢*
Macromolecules, 55(20), p.9113 - 9125, 2022/10
被引用回数：2 パーセンタイル：27.19(Polymer Science)Microphase separation of copolymers is a key technique to produce polymer bulk materials or thin films with ordered nanostructures for applications in various research fields including nanotechnologies, electronic devices, among many others. Herein, we report water-assisted microphase separation of amphiphilic random copolymers bearing quaternary ammonium cations and hydrophobic alkyl or oleyl groups in the solid state and the thin films. We investigated the effects of sample preparation protocols and the hydrophobic pendants (a butyl group: C4 - octadecyl or oleyl group: C18), composition, and molecular weight of the copolymers on the microphase separation behavior. By annealing under humid conditions, the copolymers bearing alkyl groups longer than an octyl group (C8) formed sub-5 nm lamellar structures comprising cationic layers and hydrophobic layers. Water hardly remained in the resulting lamellar materials under ambient conditions. The domain spacing was controlled between 3.7 and 5.3 nm by tuning the length of the hydrophobic pendants and composition and was independent of the molecular weight and molecular weight distribution. The cationic random copolymers carrying amorphous hydrophobic pendants provided transparent or translucent polymer materials containing small lamellar structures. The random copolymers further formed multilayered lamellar thin films on silicon substrates by spin-coating the copolymer solutions, followed by a humid annealing process. The layered lamellae were directly observed as terrace structures with about 4-5 nm steps by atomic force microscopy.
Ikami, Takaya*; Watanabe, Yuki*; 小川 紘輝*; 竹中 幹人*; 山田 悟史*; 大内 誠*; 青木 裕之; 寺島 崇矢*
ACS Macro Lett (Internet), 10(12), p.1524 - 1528, 2021/12
被引用回数：7 パーセンタイル：48.3(Polymer Science)Making ordered nanostructures in polymers and their thin films is an important technique to produce functional materials. Herein, we report instant yet precise self-assembly systems of amphiphilic random copolymers to build multilayered lamellar structures in bulk materials and thin films. Random copolymers bearing octadecyl groups and hydroxyethyl groups induced crystallization-driven microphase separation via simple evaporation from the solutions to form lamellar structures in the solid state. The domain spacing was controlled in the range between 3.1 and 4.2 nm at the 0.1 nm level by tuning copolymer composition. Interestingly, just by spin-coating the polymer solutions onto silicon substrates, the copolymers autonomously formed thin films consisting of multilayered lamellar structures, where amorphous/hydrophilic parts and crystalline octadecyl domains are alternatingly layered from a silicon substrate to the air/polymer interface at regular intervals. The lamellar domain spacing was tunable by selecting hydrophilic pendants.
寺島 崇矢*; 元川 竜平; 小泉 智*; 澤本 光男*; 上垣外 正己*; 安藤 剛*; 橋本 竹治*
Macromolecules, 43(19), p.8218 - 8232, 2010/10
被引用回数：42 パーセンタイル：77.5(Polymer Science)
and time-resolved small-angle neutron scattering (SANS) was employed for the elucidation of star polymer formation mechanism via linking reaction of living linear polymers in ruthenium-catalyzed living radical polymerization. Here, methyl methacrylate (MMA) was first polymerized with R-Cl/RuCl
(PPh
)/tribuylamine (
-BuN) initiating system, followed by the addition of ethylene glycol dimethacrylate (EGDMA: 3) as a linking agent. After the in situ addition of a small amount of 3 to living linear PMMA, the SANS analysis revealed the following three steps: (process II-1) formation of block copolymers (4) and competitive formation of the small star polymers via the linking reaction of 4 and 4; (process II-2) star-star linking of the small star polymers into star polymers and putting 4 into the core of the star polymers, leading to formation of the microgel-core star polymers; (process II-3) growth of the microgelcore star polymers (5) via placement of 4 into the microgel-core star polymers. Furthermore, the SANS profiles, obtained as a function of polymerization time, were quantitatively analyzed with a core-shell spherical model in order to determine the microstructures of the star polymers: The final reaction product had an average radius of microgel-core ( 1 nm), and average arm numbers N 17.
橋本 竹治; 元川 竜平; 寺島 崇矢*; 澤本 光男*; 上垣外 正己*; 小泉 智
no journal, ,
リビングラジカル重合法によりミクロゲル星型ポリマーを合成し、その重合過程について中性子超小角散乱によるその場・実時間観察を行った。その結果、重合の進行に伴う星型ポリマーの核サイズ,形状,空間分布状態等の重合時間依存性を明らかにすることに成功した。さらに、副生成物として得られる星型ポリマーのカップリング成分の形成メカニズムも同時に明らかにした。以上のように、これまで未解明であった星型ポリマーの生成機構を解明するに至った。
