| POLYMERS Vol.66 No.5 |
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COVER STORY
Shape Control of Polymers |
| COVER STORY: Highlight Reviews |
| Creation of Two-Dimensional Polymers | Donglin JIANG |
| <Abstract> Two-dimensional polymers and their layered covalent organic frameworks are a class of crystalline porous ploymer that enables the atomically precise integration of organic units into two-dimensional periodic structures. The most distinct structural feature is that they allow for molecular design of structures and control over both primary and high-order structuers. By virtue of these features, they have emerged as a molecular platform for structural and functional designs. Recent advances in the chemistry has quickly promoted the growth of this field. This perspective focuses on elucidating the design priciple, synthetic reactions, structural feature, diversity and control, and typical functions. Keywords: Two-Dimensional Polymers / Covalent Organic Frameworks / Topology Design / Polycondensation / Structural Control / Functional Design / Crystalline Polymers / Porosity |
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| Synthesis of Architectural Polymers via Precision Polymerization | Takuya ISONO, Toshifumi SATOH |
| <Abstract> Recent progress in precision polymerization has enabled us to synthesize a wide variety of macromolecular architectures, including star, comb, cyclic, and multicyclic polymers, with well-defined structures and narrow dispersity. Such macromolecular architectures are of interest from the view point of controlling the physical properties and functions of the polymers without chainging the chemical composition and molecular weight. Particular attention is now focusing on block copolymers with complex architectures to study their interesting self-assembly behaviors. This paper gives an overview of the synthetic approaches to these macromolecular architectures, such as star-shaped and cyclic homo/block polymers. In addition, usefullness of such macromolecular architectures in functional polymer design will also be mentioned. Keywords: Living Polymerization / Nonlinear Polymer / Star Polymer / Cyclic Polymer / Block Copolymer / Self-Assembly |
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| Polymer Topology Transformation and Property Control Produced by Movable Linking of Polymer Chains | Toshikazu TAKATA, Daisuke AOKI |
| <Abstract> The shape of topology of polymers has very close relation to polymer property and function. This review article deals with reversible structure transformation systems of polymers having rotaxane cross-links at the linking points of polymer chain. In particular, linear-cyclic polymer topology transformation and linear-star (or branched) polymer topology transformation are discussed along with the change in physical and mechanical property and function caused by the topology transformation. The polymer topology is changed from linear to cyclic by moving the wheel component of [1]rotaxane introduced into the axle polymer terminal, resulting in the occurrence of the clear change in hydrodynamic volume. Similar property change is also confirmed by linear-star polymer topology change. In addition, we also introduce the synthesis of cross-linked polymers possessing rotaxane cross-links and toughening of cross-linked polymers by the rotaxane cross-link. The stress-strain curves of the rotaxane cross-linked polymer showed much higher mechanical property probably produced by the stress-releasing by the rotaxane cross-link. Keywords: Rotaxane Linkage / Movable Linking / Topology Transformation / Polymer Topology / Cyclic Polymer / Star Polymer / Cross-Linked Polymer / Polymer Toughening |
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| COVER STORY: Topics and Products |
| Morphology Control of Polymer Materials by Using Crystals | Yuya OAKI |
| <Abstract> Morphologies of organic and inorganic polymer materials are controlled by using crystals. This article focuses on morphology control of organic polymer materials. The interspace, surface, and structure of crystals were used for morphology control of polymer materials, such as redox-active polymers. The hierarchical morphology consisting of the oriented nanocrystals, such as biominerals, was used for the morphology replication from the crystals to the polymers. The hierarchical morphology of polymer materials from nanoscopic to macroscopic scales showed the improved electrochemical and adsorbent properties. The crystal surface was used for synthesis and morphology control of polymer materials. The surface of oxidant crystals formed the hierarchical morphology of conductive polymers. The layered crystal structure of the monomer used for the morphology control through the intercalation and the exfoliation. The metal-ion-intercalated polydiacetylene showed tunable stimuli-responsive color-change properties. The exfoliation of the layered polydiacetylene generated the nanosheets. These approaches can be applied to morphology control of a variety of polymer materials. Keywords: Crystals / Crystal Growth / Morphology Control / Hierarchical Structure / Conductive Polymers / Layered Compounds / Polydiacetylene / Intercalation |
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| Molecular Grid: Pursuit of Ultimate Structure over 15 Years | Yasuhiro ISHIDA |
| <Abstract> We have recently found that the salt of a polymerizable amphiphilic carboxylic acid with a chiral amine forms a stable thermotropic liquid crystal. The liquid-crystalline salt, when prepared under magnetic field, takes molecularly ordered structure in a large area. By in-situ polymerization of the carboxylic acid units, cross-linked polymer with the similar structure to the parent liquid crystal is obtained. The resultant polymer serves as a covalent framework, which can reversibly incorporate cationic and basic guest molecules. Taking advantage of its single-crystal like order, the structure of the framework was thoroughly investigated by X-ray diffraction analysis, which revealed that the framework is composed of one-handed helices. When a chromophore was incorporated in the framework, the resultant assembly exhibited nonlinear optical properties, originating from the chirality of the framework. Keywords: Chirality / Crosslinking / Helix / Liquid Crystal / Magnetic Orientation / Solid-State Host / Supramolecular Chemistry / Template Reaction |
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| Solution Properties of Helical Polysaccharide Derivatives | Ken TERAO |
| <Abstract> Polysaccharide carbamate derivatives, which are well known as chiral stationary phases, are generally well soluble in organic solvents even though they have a relatively stiff main chain. We determined the helix pitch per residue value as well as the chain stiffness for six amylose carbamate derivatives of in total 31 systems and found that both parameters vary in a certain range. Furthermore, we were able to obtain rigid and semiflexible cyclic polymers in terms of the carbanilation of flexible cyclic amylose. These cyclic derivatives may have appreciably different local conformation, indicating that the helical structure of amylosic chains should fluctuate in solution at room temperature. The high solubility of polysaccharide derivatives may be reason allowing these conformational features. Keywords: Amylose Carbamates / Wormlike Chains / Chain Stiffness / Helical Structure / Hydrogen Bonds / Two State Model / Cyclic Chains |
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| Polymer Science and I: A Personal Account |
| Positive Mental Attitude | Kazuhide UENO |
| <Abstract> Kazuhide Ueno received his Ph.D. in 2009 from Yokohama National University (supervised by Prof. M. Watanabe). He was a postdoctoral fellow at Tohoku University, at Arizona State University, and at Yokohama National University. He was appointed as assistant professor at Yamaguchi University in 2015, and as associate professor at Yokohama National University in 2017. His research interests include ionic liquid-based soft materials, and battery electrolytes. |
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| Front-Line Polymer Science |
| Physical Properties of Ring Polymers and Their Derivatives | Yuya DOI, Atsushi TAKANO, Yoshiaki TAKAHASHI, Yushu MATSUSHITA |
| <Abstract> Understanding of the properties of ring polymers is one of the central subjects in polymer physics. Thanks to the development in separation and purification techniques of ring polymers, highly-purified ring polymers could be prepared, and the studies on ring polymers have progressed. In this article, we briefly summarize recent discoveries of physical properties, especially viscoelastic properties, of ring polymers and their derivatives such as tadpole-shaped polymer and dumbbell-shaped polymer. Keywords: Ring Polymer / Tadpole-Shaped Polymer / Dumbbell-Shaped Polymer / Physical Property / Rheology |
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