Synthesis of Amphiphilic Three-Armed Star Random Copolymers via Living Radical Polymerization and their Unimolecular Folding Properties in Water

Amphiphilic three-armed star random copolymers were synthesized by ruthenium-catalyzed living radical copolymerization of hydrophilic poly(ethylene glycol) methyl ether methacrylate (PEGMA) and hydrophobic dodecyl methacrylate (DMA). Their amphiphilic star random copolymers with 10-50 mol% DMA efficiently self-folded in water with intramolecular hydrophobic interaction to form compact unimolecular micelles. Owing to PEG segments, star copolymers were thermoresponsive to induce lower critical solution temperature-type phase separation in water

Polymeric pseudo-crown ether for cation recognition via cation template-assisted cyclopolymerization.

Cyclopolymerization is a chain polymerization of bifunctional monomers via alternating processes of intramolecular cyclization and intermolecular addition, to give soluble linear polymers consisting of in-chain cyclic structures. Though cyclopolymers comprising in-chain multiple large rings potentially show unique functionality, they generally require the elaborate design of bifunctional monomers. Here we report cation template-assisted cyclopolymerization of poly(ethylene glycol) dimethacrylates as an efficient strategy directly yielding polymeric pseudo-crown ethers with large in-chain cavities (up to 30-membered rings) for selective molecular recognition. The key is to select a size-fit metal cation for the spacer unit of the divinyl monomers to form a pseudo-cyclic conformation, where the two vinyl groups are suitably positioned for intramolecular cyclization. The marriage of supramolecular chemistry and polymer chemistry affords efficient, one-pot chemical transformation from common chemical reagents with simple templates to functional cyclopolymers

カチオンジュウゴウニオケルセイチョウタンソカチオンニカンスルケンキュウ

京都大学0048新制・課程博士工学博士甲第2253号工博第616号新制||工||445(附属図書館)6166UT51-54-P312京都大学大学院工学研究科高分子化学専攻(主査)教授 東村 敏延, 教授 今西 幸男, 教授 伊勢 典夫学位規則第5条第1項該当Kyoto UniversityDA

Fluorinated microgel star polymers as fluorous nanocapsules for the encapsulation and release of perfluorinated compounds

Accepted 05 Feb 201

A strategy for sequence control in vinyl polymers via iterative controlled radical cyclization.

高分子のモノマー配列を制御する手法の開発. 京都大学プレスリリース. 2016-03-23.There is a growing interest in sequence-controlled polymers toward advanced functional materials. However, control of side-chain order for vinyl polymers has been lacking feasibility in the field of polymer synthesis because of the inherent feature of chain-growth propagation. Here we show a general and versatile strategy to control sequence in vinyl polymers through iterative radical cyclization with orthogonally cleavable and renewable bonds. The proposed methodology employs a repetitive and iterative intramolecular cyclization via a radical intermediate in a one-time template with a radical-generating site at one end and an alkene end at the other, each of which is connected to a linker via independently cleavable and renewable bonds. The unique design specifically allowed control of radical addition reaction although inherent chain-growth intermediate (radical species) was used, as well as the iterative cycle and functionalization for resultant side chains, to lead to sequence-controlled vinyl polymers (or oligomers)

Transfer hydrogenation of ketones catalyzed by PEG-armed ruthenium-microgel star polymers: microgel-core reaction space for active, versatile and recyclable catalysis

Poly(ethylene glycol) (PEG)-armed Ru(II)-bearing microgel-core star polymer catalysts were used for the transfer hydrogenation of ketones. The star catalysts (Ru(II)-PEG Star) were one-pot synthesized by ruthenium-catalyzed living radical polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and a sequential linking reaction with ethylene glycol dimethacrylate (1) and diphenylphosphinostyrene (2). The polymers efficiently and homogeneously reduced acetophenone into 1-phenylethanol in 2-propanol coupled with K2CO3 at a high yield, despite a low catalyst feed ratio to the substrate (Ru(II)/substrate=1/1000). Importantly, the catalytic activity was higher than that of the original RuCl2(PPh3)3, as well as that of similar polymer-supported Ru(II) catalysts, such as poly(methyl methacrylate)-armed star-, polystyrene gel- and random polymer-supported catalysts. Ru(II)-PEG Star is applicable to various substrates, including para-substituted aromatic, aliphatic and bulky ketones, where the activity of Ru(II)-PEG Star is is generally higher than that of RuCl2(PPh3)3. For example, the turnover frequency for 4-chloroacetophenone and cyclohexanone reached ~1000 h−1, and the reduction rate of cyclopentanone and 3-methyl-5-heptanone was twice as high as that of RuCl2(PPh3)3. The star catalyst also showed high catalyst recyclability, independent of the substrate species. These features most likely arise from its unique reaction space, which consists of a ruthenium-embedded, hydrophobic microgel core surrounded by amphiphilic and polar PEGMA arms

Unprecedented Sequence Control and Sequence-Driven Properties in A Series of AB-Alternating Copolymers Consisting Solely of Acrylamide Units

1種類のモノマー単位で交互共重合体の合成に成功 --異なる側鎖の配列制御で液晶性を発現--. 京都大学プレスリリース. 2020-01-16.In this article, we report a method to synthesize a series of alternating copolymers that consist exclusively of acrylamide units. Crucial to realizing the unprecedented polymer synthesis is the design of a divinyl monomer that contains acrylate and acrylamide moieties connected via two activated ester bonds. This elaborate design, which is based on the reactivity ratio of the embedded vinyl groups, allows a “selective” cyclopolymerization, wherein the intramolecular and intermolecular propagation are repeated alternately under dilute conditions. The addition of an amine to the resulting cyclopolymers afforded two different acryl amide units, i.e., an amine‐substituted acryl amide and a 2‐hydroxy‐ethyl‐substituted acryl amide in alternating sequence. Using this method, we were able to furnish ten types of alternating copolymers; some of these exhibit unique properties in solution and in the bulk, which are clearly different from those of the corresponding random copolymers, and we attributed the observed differences to the alternating sequence

Amphiphilic/fluorous random copolymers as a new class of non-cytotoxic polymeric materials for protein conjugation

Accepted 22 Oct 2014.Herein, amphiphilic/fluorous random copolymers bearing poly(ethylene glycol) (PEG) chains and perfluorinated alkane pendants were developed as novel non-cytotoxic polymers for protein conjugation. Three kinds of random copolymers with different initiating terminals (carboxylic acid, pyridyl disulfide, and N-hydroxysuccinimide ester) were prepared by reversible addition–fragmentation chain transfer (RAFT) copolymerization of a PEG methyl ether methacrylate and a perfluorinated alkane methacrylate with the corresponding functional chain transfer agents. All of the polymers were soluble in water to form nanostructures with perfluorinated compartments via fluorous interaction: large aggregates from the intermolecular multi-chain association and compact unimer micelles from the intramolecular single-chain folding. Such a PEGylated and perfluorinated random copolymer was non-cytotoxic to NIH 3T3 mouse embryonic fibroblast cells and human umbilical vein endothelial cells (HUVECs). Additionally, a random copolymer with a pyridyl disulfide terminal was also successfully conjugated with a thiolated lysozyme