| POLYMERS Vol.73 No.1 |
| >> Japanese | >> English |
COVER STORY
Cutting-Edge of Precisely Designed Network Polymers |
| COVER STORY: Highlight Reviews |
| Elucidation of Crosslink Inhomogeneity of Phenolic Resins | Yasuyuki SHUDO, Atsushi IZUMI |
| <Abstract> In order to elucidate the crosslink inhomogeneity of phenolic resins, we investigated the structure of swollen gels immediately after gelation and fully cured resins using X-ray and neutron scattering techniques. We present in this paper examples of solvent diffusion analysis in cured resin using incoherent neutron quasi-elastic scattering and analysis of inhomogeneous nanostructures at the phenolic resin / silica interface using neutron reflectometry. By taking advantage of the difference in scattering ability between probes and scatterers, and by using coherent/incoherent scattering and elastic/inelastic scattering, it is now possible to understand the inhomogeneous crosslink structure and its formation mechanism of phenolic resin. Keywords: Phenolic Resins / Thermosetting Polymers / Small-Angle X-Ray Scattering / Small-Angle Neutron Scattering / Quasi-Elastic Neutron Scattering / Neutron Reflectometry |
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| Network Polymers Composited with Liquid Crystalline Nanosheets | Nobuyoshi MIYAMOTO |
| <Abstract> Inorganic nanosheets dispersed in a solvent form liquid crystalline phases with highly tunable hierarchical superstructures. In this article, recent developments of new type network polymers composited with liquid crystalline nanosheets are presented, which show intriguing anisotropic properties. Keywords: Nanosheet / Liquid Crystal / Gel / Elastomer / Structural Color / Anisotropy |
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| New Stream in Gel Science Driven by Tetra Gel | Takamasa SAKAI, Xiang LI |
| <Abstract> Homogeneous gels not only advance our understanding of gels themselves, but also impact the surrounding field. They are helping to advance methods for detecting inhomogeneities, pioneering new biological observation techniques through gels, and advancing the creation of perfectly homogeneous gels. As the correlation between structure and physical properties is uncovered, it promotes the systematic development of gel materials, paving the way for their broader societal implementation. Keywords: Tetra Gel / Ideal Network / Non-Ergordicity / Network Disassembly Spectrometry / Expansion Microscopy / Dynamic Light Scattering |
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| COVER STORY: Topics and Products |
| Self-Healable Ion Gels from Physical Entanglements of Ultrahigh–Molecular Weight Polymers | Ryota TAMATE |
| <Abstract> Highly stretchable and self-healing polymer gels formed solely by physical entanglements of ultrahigh–molecular weight (UHMW) polymers are fabricated through a facile one-step process. Radical polymerization of vinyl monomers in ionic liquids under very low initiator concentration conditions produces UHMW polymers of more than 106 g/mol with high monomer conversion, resulting in the formation of physically entangled polymer gels. The UHMW gels show excellent properties, such as high stretchability, high ionic conductivity, and recyclability. Furthermore, the UHMW gel exhibits room temperature self-healing ability without any external stimuli. The tensile experiments and molecular dynamics simulations indicate that the nonequilibrium state of the fractured surfaces and microscopic interactions between the polymer chains and solvents play a vital role in the self-healing ability. This study provides a physical approach for fabricating stretchable and self-healing polymer gels based on UHMW polymers. Keywords: Self-Healing / Ultrahigh Molecular Weight / Ionic Liquids / Ion Gels / Physical Entanglements / Stretchable |
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| Use of Biological Tissues toward Precise Synthesis of Soft Materials | Tasuku NAKAJIMA |
| <Abstract> Biological tissues have a precise and hierarchical internal structure, which plays an essential role in their excellent properties and functions. In order to create synthetic materials with such biotissue-like properties, it is necessary to construct a precise internal structure inside them. While outstanding chemists are tackling this issue with their precise synthesis techniques, we, beginners of synthetic chemistry, do not have such chemical techniques. Instead of using precise chemistry, we adopt the other way to construct precise materials; that is, using existing biological tissues with precise internal structure that act as substrates of biological/synthetic hybrid materials. As an example, here I report the squid/polyacrylamide hybrid hydrogels with excellent fracture toughness. Squid mantles have well-oriented circle muscle fibers. We synthesized the polyacrylamide network in the squid mantle to create the hybrid hydrogels. Such the hybrid hydrogels exhibit excellent fracture toughness owing to the oriented muscle fibers of the squid inside them. Keywords: Biological Tissues / Composite / Hybrid / Hydrogel / Anisotropy / Toughness / Squid / Cuttlefish |
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| Funtional Hydrogels Based on Design of Nanodomain Structure | Shohei IDA |
| <Abstract> Elaborate design and precise construction of network structures is required for the development of novel hydrogel materials. We are focusing on the design of a stimuli-responsive nanodomain structure in a hydrogel using living radical polymerization techniques. For example, a dispersed and crosslinked nanodomain consisting of thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) was incorporated into a hydrogel through reversible addition-fragmentation chain transfer (RAFT) polymerization. The product hydrogels exhibited thermoresponsive mechanical toughening maintaining their original volume and transparency due to the swelling/shrinking of the nanodomains. The consistent transparency at a high temperature was observed even with as high as 50％ of thermoresponsive content. This feature allowed us to hybridize functional molecules with such hydrogels to realize the multifunctional properties in response to one stimulus. Incorporation of fluorescent carbon dots led to a simultaneous mechanical toughening and change in photoluminescence. Furthermore, the functionalization with an iridium complex afforded a hydrogel showing molecular sensing with a drastic color change and catalytic activity in N-alkylation reaction. Keywords: Hydrogels / Living Radical Polymerization / RAFT Polymerization / Nanodomains / Mechanical Properties / Themoresponsive Properties / Carbon Dots / Iridium Complex |
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| Polymer Science and I: A Personal Account |
| Beyond “Switch ON” | Ken MORISHIMA |
| <Abstract> I have studied the structure and physical properties of various soft matters, and I am currently working on biomacromolecules. I would like to make new discoveries through mastering the professionalism of measurements. |
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| Front-Line Polymer Science |
| Precisely Controlled Synthesis of Silsesquioxanes | Yoshiro KANEKO |
| <Abstract> In this topic, I would like to focus on the fundamental structural control methods of silsesquioxanes (SQ), particularly polyhedral oligomeric SQ (POSS), because SQ has shown expanding applications in various fields. Specifically, I will discuss the size-controlled synthesis of POSS and explore the effects of the type of reaction solvent and reaction temperature/time on POSS size. Furthermore, I will explain the synthesis of large-sized POSS, including 18-mer POSS and macrocyclic ladder-like SQ. Additionally, I will present the syntheses of POSS with controlled arrangement of different side-chain groups, including POSS with a bifacial structure and para- and ortho-substituted POSS. Keywords: Silsesquioxane / POSS / Organic-Inorganic Hybrid / Precisely Controlled Synthesis |
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