| 高分子 Vol.70 No.12 |
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特集 リング－環状高分子－
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| 展望 COVER STORY: Highlight Reviews |
| さまざまなトポロジーの高分子と物理 Polymers with Various Topologies and Physics |
出口 哲生 Tetsuo DEGUCHI |
| ＜要旨＞ 熱揺らぎの中で環状高分子のトポロジー（結び目）は一定であり、エントロピーは結び目確率の対数に対応する。結び目確率に関する和則が最近見いだされた。その説明のために結び目理論の基礎概念を説明し、環状高分子や結び目DNAの従来の研究を振り返り、トポロジカル高分子（グラフ型高分子）や高分子ネットワークへ展開する展望を述べる。 Keywords: Ring Polymer / Knot / DNA / Knotting Probability / Sum Rule |
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| 精密重合法を用いた環状高分子の効率的合成 Efficient Construction of Cyclic Polymers Enabled by Precise Polymerization and Cyclizations |
間藤 芳允・磯 野拓也・佐藤 敏文 Yoshinobu MATO, Takuya ISONO, Toshifumi SATOH |
| ＜要旨＞ 精密重合法の発展はかたち（トポロジー）やサイズが制御されたさまざまな環状高分子の合成を可能にしてきた。本稿では、環状高分子の合成法を概説し、環状高分子の材料応用を加速させ得る効率的合成法の新展開を紹介する。 Keywords: Polymer Topology/ Cyclic Polymer / Multicyclic Polymer / Precision Polymerization / Consecutive Cyclization |
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| トピックス COVER STORY: Topics and Products |
| 環拡大ビニル重合 Ring-Expansion “Vinyl” Polymerization |
鳴海 敦 Atsushi NARUMI |
| ＜要旨＞ Ring-expansion “vinyl” polymerization remains an unestablished methodology in polymer synthetic chemistry in which vinyl monomers are inserted into the backbones of ring-shaped molecules via addition polymerizations. We have projected to utilize the nitroxide-mediated controlled radical polymerization (NMP) to develop such polymerizations. Alkoxyamine derivatives were tethered to produce cyclic NMP initiators, which were used for the polymerizations of styrene (St). In addition to the featured characteristics of the polymerizations, we have explored model reactions among the cyclic NMP initiators and also the brush-modification and subsequent AFM observations. In particular, the microscopic data allowed to quantitatively discuss the details of the reactions taking place in the present system, such as the ring-expansion “vinyl” polymerizations generating cyclic polymers, the fusion of cyclic polymers to form multimers, and their scissions to form linear species. The author expects these outcomes will lead to an advanced morphology-controlled polymerization method to incorporate significant values to the conventional vinyl polymers. Keywords: Polymer Synthesis / Ring-Expansion Polymerization / Controlled Radical / Polymerization / Cyclic Initiator / Macrocyclic Polymer / Multimer / Morphology / Atomic Force Microscopy (AFM) |
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| 高分子の環状と鎖状の可逆的トポロジー変換 Linear/Cyclic Topology Transformation of Polymers |
中薗 和子 Kazuko NAKAZONO |
| ＜要旨＞ The recent development of reversible linear-cyclic polymer structural transformation is reviewed. The conversion of linear and cyclic polymer topologies involves the process of efficient transforming to the cyclic topology by reactions between the ends of the telechelic polymer and to the linear topology by selective bond breaking to generate the initial telechelic polymer. In order to carry out such polymer reactions efficiently, dynamic covalent bond chemistry and reversible covalent bond formation by photo and thermally controlled reactions are utilized. Furthemore, environmentally responsive linear-cyclic polymer structural conversions have also been achieved by using non-covalent bonds such as hydrogen bonds and host-guest complexes as reversible bonds. Finally, recent advances of a new linear-cyclic structure conversion method utilizing the dynamic properties of macromolecular rotaxanes without using the conventional ring closing process is also described. Keywords: Cyclic Polymer / Polymer Topology / Reversible Topologyical / Transformation/Rotaxane |
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| 環状高分子のトポロジーの数学的考察 Mathematical Analysis of the Topology of Cyclic Polymers |
下川 航也 Koya SHIMOKAWA |
| ＜要旨＞ In this article, we will discuss the topology of cyclic and multicyclic polymers. There are two aspects to the topology of polymers. One is the graph theoretical aspect, which reveals the intrinsic topology of polymers arising from the connection structure consisting of branch points and linear chains. Using graph theory, we will discuss the nomenclature of graphs corresponding to multicyclic polymers. The other is the knot theoretic aspect, which describes its extrinsic topology, the 3-dimensional shape of polymers. The structure of knots, links, and spatial graphs will reveal properties such as topological stereoisomerism and topological chirality. Recently, very complex molecular structures made of links have been constructed and will be reported. Keywords: Cyclic Polymer / Multicyclic Polymer / Topology / Knot / Link / Catenane / Graph / Spatial Graph |
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| 環状RNAを鋳型としたタンパク質翻訳 Rolling Circle Translation of Circular RNA |
中嶋 裕子・福地 康佑・阿部 奈保子・阿部 洋 Yuko NAKASHIMA, Kosuke FUKUCHI, Naoko ABE, Hiroshi ABE |
| ＜要旨＞ Circular RNAs have a continuous structure and are more stable in vivo than linear RNAs. Recently, transcriptome analysis has revealed the existence of endogenous circular RNAs, some of which have translatable open reading frames. However, the mechanism of how these circular RNAs are translated in the cell is still unclear. We have reported that circular RNAs containing an infinite open reading frame can be efficiently translated to produce proteins in an Escherichia coli cell-free translation system and in living human cells. This translation system is called “rolling circle translation.” In this system, the circular RNA contains a no stop codon and the number of nucleotides composing the RNA is a multiple of three. The mechanism of rolling circle translation not only provides a long-repeating peptide sequence but also enhances the productivity over a given period of time, because the ribosome does not need to bind to the RNA template multiple times, which is the rate limiting step in the reaction cycle. Keywords: Circular RNA / Translation / Rolling Circle Translation |
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| グローイングポリマー Polymer Science and I: A Personal Account |
| 好きなことで、生きていく Live by What You Love |
井本 裕顕 Hiroaki IMOTO |
| ＜要旨＞ In today’s world, it is natural to live by what you love. I have wanted to be a chemist since I was a child, and now I am living by what I love. |
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| 高分子科学最近の進歩 Front-Line Polymer Science |
| 環状高分子の分離精製とキャラクタリゼーション－最近の進歩－ Recent Development in Separation, Purification, and Characterization of Ring Polymers |
高野 敦志 Atsushi TAKANO |
| ＜要旨＞ Ring polymers is one of the most interesting model polymers especially from the aspect of the polymer dynamics, because they have no chain ends. By the recent development of HPLC techniques with high resolution, highly-purified ring polymers could be prepared, and the understanding of essential physical properties on ring polymers have been progressing. In this article, further developments in separation, purification, and characterization of ring polymers are described. Keywords: Ring Polymer / Separation / Purification / Characterization / Viscoelastic Property |
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