| POLYMERS Vol.68 No.3 |
| >> Japanese | >> English |
COVER STORY
Nature of Macromolecules |
| COVER STORY: Highlight Reviews |
| What is the “Polymer-Like“ in Self-Assemblies of Block Copolymers | Hiroshi JINNAI |
| <Abstract> Block copolyers (BCPs) self-assemble to vriouus periodic nano-scale structures. Other molecular systems, such as microemultions and giant molecules, share essentially the same physical background (as BCP) and likewise self-assemble periodic structures. Comparing BCP structures with those in other molecular systems, however, one notices that some of the periodic structures found in the moleular systems are missing in the BCP motphologies. In this article, we disucuss why such difference both in the phase behavior and in dynamical processes happens in terms of distributions intrinsically exsiting in BCPs. Keywords: Block Copolymers / Self-Assembly / Electron Microscopy / Electron Tomography / Molecular Weight Distribution |
| Top of the Page▲ |
| Polyrotaxane and Slide-Ring Materials | Kohzo ITO |
| <Abstract> We have recently developed a novel type of polymer network called slide-ring materials by cross-linking a polyrotaxane, the supramolecular architecture with topological characteristics.1) In this type of network, polymer chains are topologically interlocked by figure-of-eight cross-links. Hence, these cross-links can pass along the polymer chains freely to equalize the tension of the threading polymer chains similarly to pulleys. The structure and physical properties of the polymeric materials are drastically different from conventional cross-linked or noncross-linked materials. For instance, the slide-ring gel or elastomer shows quite small Young’s modulus, which is not proportional to the cross-linking density and much lower than those of chemical gels with the same density. This arises from the difference in the molecular mechanism of the entropic elasticity: While the conformational entropy is mainly responsible for the elasticity in usual chemical gels or rubbers, the mechanical properties of the slide-ring gel should be inherently governed by the alignment entropy of free cyclic molecules in the polyrotaxane as well as the conformational entropy of the backbone polymer. This means that the softness in the slide-ring gel is due to the novel entropic elasticity, which is also expected to yield sliding state and sliding transition. Consequently, the slide-ring materials have the dynamic coupling between two kinds of entropy: the conformational entropy of strings and alignment entropy of rings.2,3) The concept of the slide-ring gel is not limited to cross-linked gels but also includes elastomers, cross-linked polymeric materials without solvent. Accordingly it can be applied to a wide area such as soft contact lens, paints, rubbers, soft actuator and so on. As a typical example, the scratch-resist properties of the self-restoring slide-ring elastomer were adopted into the top coating on a mobile phone. Finally, I would like to introduce the ImPACT (Impulsing Paradigm Change through Disruptive Technologies) program, which is promoting to create flexible and tough polymers by using the slide-ring materials as a key technology. Keywords: Cross-Link / Polyrotaxane / Supramolecule / Mechanical Properties |
| Top of the Page▲ |
| Cooperative Phenomena of Polymers and Associative Molecules | Tsuyoshi KOGA |
| <Abstract> Characteristic structure formaiton is induced by coorperation of polymers and associative molecules. Polyrotaxane, which is well-known as one of functional polymers, is formed by such cooperation of polyethylene glycol and cyclodextrin. This article reviews recent developments in the study on the formation of polyrotaxane with paying special attention on polymer characteristics. Keywords: Polymer / Association / Cyclodextrin / Polyrotaxane / Cooperative Phenomena / Inclusion Complex / Statistical Mechanical Theory / Molecular Simulation |
| Top of the Page▲ |
| COVER STORY: Topics and Products |
| Relationship between Mechanical Properties and Nano-Structure of the Transient Network Structure Constructed with Amphiphilic Polymers | Isamu KANEDA |
| <Abstract> HEURs, which is a type of amphiphilic polymers, construct transient networks in water and these networks become physical gels. These physical gels are utilized as a thickener in cosmetics, because they show unique rheological properties. A study on the concentration dependency of the mechanical properties and their nano-structures that are observed using SAXS have been perfomed. Mechanical poperties of the physical gels metastasized at around 2 wt%. It has been found that this phenomenon is caused by the change of the polymer assembly structures of the gels by employing SAXS studies. Keywords: Amphiphilic Polymers / HEUR / Physical Gels / Rheology / SAXS |
| Top of the Page▲ |
| Analysis of Protein Interactions to Create Protein Materials | Satoru NAGATOISHI, Makoto NAKAKIDO, Kouhei TSUMOTO |
| <Abstract> Proteins are sophisticated molecules, which have a variety of functions. Development of novel materials based on understanding of the molecular mechanisms of the protein functions would have a tremendous potential. Here, we introduce our recent studies related to protein fibril formation. First, we developed an original “protein schackle”, which can form fibrils in oxidation condition dependent manner. We also showed the intermolecular weak interaction, of which Kd was around mM range, have a critical role in the polymerizaiton reaction. In the second study, we revealed OMD, a protein that belongs to small leucine rich repeat proteoglycan family, regulates the fibril formation of collagens through interaction with pre-mature collagen fibrils. Although the affinity of the interaction is weak and tentative, the interaction has critical effect on appropriate fibril formation of collagen. Both examples clearly show that “weak intermolecular interaction” has a important role in the regulation of fibril formation. We hope these findings will contribute to the development of novel protein-based materials. Keywords: Protein-Protein Interaction / Weak Intermolecular Interaction / Fibril Formation |
| Top of the Page▲ |
| Topological Interaction in Ring Polymers | Daichi IDA |
| <Abstract> Topological interactions in ring polymers arise only from the chain connectivity. In this short article, there are briefly summarized the Monte Carlo studies of effects of the intra- and intermolecular topological interactions on the scattering function and second virial coefficient, respectively, of the wormlike ring model. A comparison between experimental data and the results for the wormlike ring is also shown. Keywords: Ring Polymers / Scattering Function / Second Virial Coefficient / Topological Interaction / Wormlike Ring |
| Top of the Page▲ |
| Polymer Science and I: A Personal Account |
| Gute Reise und Viel Spaß !! | Ryohei KAKUCHI |
| <Abstract> This essay highlights the author’s stint in Germany as a postdoctoral researcher and documents how the stay in Germany affected the author’s life and the way of thinking. |
| Top of the Page▲ |
| Front-Line Polymer Science |
| Polymer Nanomechanics | Ken NAKAJIMA |
| <Abstract> The recent progress in the field of “polymer nanomechanics” is reviewed, which is based on atomic force microscope (AFM), the author’s expertise. Starting from its histrical background which focused on so-called tapping-mode, the contributions of materials’ elasticity and viscosity, adhesive interaction to imaging contrast are discussed. Then, nano-palpation AFM is introduced where quantitative nanomecanical analyses of materials’ elasticity became possible. Further attempts to realize the visualization of viscoelasticity are reviewed, appeared within several years. Viscocity mapping based on Johnson’s standard linear solid model enabled us to obtain a suble difference in materials’ properties between two types of rubbers in a blend specimen. Our newly-developed nanorheological AFM was finaly introduced, by which the quantitative measurement of dynamic moduli with broad frequency range came true. The possible violation of time-temperature superposition principle was indicated by this method, where the heterogeneous glass-rubber transition was observed at nano-scale for vulcanized rubber specimen. Keywords: Polymer Nanomechanics / Atomic Force Microscope / Viscoelasticity / Time-Temperature Superposition Principle / Glass-Rubber Transition / Heterogeneity |
| Top of the Page▲ |
| Copyright(C) 2019 The Society of Polymer Science, Japan All Rights Reserved. |