| POLYMERS Vol.70 No.7 |
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COVER STORY
Polymers Meet Biomimetics |
| COVER STORY: Highlight Reviews |
| Biomimetics in Germany－Research Embedded in Network and Standardization | Iwiza TESARI, Rainer ERB, Claus MATTHECK |
| <Abstract> Even if the terms networks and standardization do not immediately come to mind when thinking of biomimetics research, they have been supporting it in Germany for years. BIOKON, the German Biomimetics Network of Excellence, promotes exchange between scientists and especially between research and application through networking. Structured and continuous knowledge transfer at the interface between science and industry is essential to stay ahead in the innovation race. Standards also help bridging the gap between the wide range of different research disciplines and practical application. They create trust and provide users in business and industry access to the tremendous potential of biomimetics. Here, an insight into the German networking and standardization activities in the field of biomimetics will be given. In addition, some selected research fields of biomimetics in Germany are briefly described. This concerns self-cleaning surfaces, optimization methods and biopolymers. Keywords: Biomimetics / Standardization / BIOKON / Network / Optimzation / Self-cleaning Surfaces / Biopolymers |
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| Toward the Creation of Artificial Silk that Mimics the Hierarchical Structure of Spider Dragline | Keiji NUMATA |
| <Abstract> Spider silk's mechanical properties originates from the hierarchically organized structures. However, the molecular mechanism for silk fiber formation has not been elucidated yet because the transient intermediate structures remain unresolved. This mini-review summarizes the recent update on an integrated model for spider silk assembly based on the dragline spidroin MaSp2. This incorporates the action of multiple chemical and physical gradients to enable self-assembly of silk proteins into hierarchical fibres mimicking the native state. Central to the mechanism is a liquid-liquid phase separation (LLPS) that occurs in response to multivalent anions such as phosphate, and is mediated by C-terminal and core repeat regions. A second gradient—a pH decrease—triggers the rapid assembly of nanofibrils in response to N-terminal domain oligomerization, giving rise to a liquid-to-solid phase transition. Application of mechanical stress to the nanofibrillar structures yields hierarchical fibres with β-sheet conformation. These findings on the inducible phase separation of silk proteins are corroborated by investigations using native spidroins. Keywords: Spider Silk / Major Ampullate Spidroin (MaSp) / Structural Protein / Hierarchical Structure / Liquid-Liquid Phase Separation (LLPS) / Fiber |
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| Observation Technique that Supports Biomimetics and Informatics: Living Biological Surface Analysis by the NanoSuit Method | Takahiko HARIYAMA |
| <Abstract> Scanning electron microscopy (SEM) has made remarkable progress and has become an essential tool for observing biological materials at a microscopic level, especially in biomimetics research. However, various complex procedures have precluded observation of living organisms to date. Here, a new method coined the “NanoSuit®” is presented by which living organisms can be observed by an ordinary SEM. The irradiation by electron beams or plasmas to the surface of certain multicellular organisms can coat of thin polymer membrane made of extracellular substances (ECS), which acts as a barrier to the passage of gases and liquids and thus protects the organism. Based on this discovery, we invented the coating method by the “biomimetic ECS” composed of biocompatible substance for the organism which lack the natural ECS. The new “NanoSuit®” methods will be useful for numerous applications, particularly in the life sciences. Keywords: NanoSuit® / Nano-Polymer / Electron Microscope / Living Organisms / Thin Membrane / Morphology / Biomimetics |
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| COVER STORY: Topics and Products |
| Adhesive Materials - Learning from A Clingfish Sucker Disk | Yuji HIRAI, Kazuma TSUJIOKA |
| <Abstract> Clingfishs rapidly adhere on a rocky surface under water by their ventral sucker disk. The sucker disk margin consistes of hierarchical structures; nanofilaments formed on the micron-scale papillae, and the structures were completley covered by sticky mucus. To investigate the effect of the nanofilaments, we demonstrate the preparation and the adhesion measurement of the mimicked structures. The nanofilaments were prepared by hot-press of a polystyrene sheet using anodic aluminum oxide as a mold, and simply spin-coated by the polydimethylsiloxane (PDMS). As results of the adhesion measurements, adhesive strength of the mimicked structures were stronger than that of the flat PDMS surface. Furthermore, the results were also supported by the finite element method simulations. According to these results, the nanofilaments of the clingfish acts as a hard bracing to disperce deformation stress for enhancing adhesive strength, and this strategy can be applicable for a wide variety of the field. Keywords: Biomimetics / Sucker Disk / Adhesive / Clingfish / Nanostructure |
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| Bio-Inspired On-Surface Synthesis of Nano Carbon Materials | Shunpei NOBUSUE, Takahiro NAKAE, Hiroshi SAKAGUCHI |
| <Abstract> Chemical vapor deposition is a powerful tool to fabricate carbon nanomaterials, which consists of decomposition and reconstruction process of precursors at high temperature. On the contrary, biomimetics has recently been attracting a great interest to fabricate biomaterials at room temperature by mimicking the nature of biological systems. However, on-surface synthesis of electronic materials at high temperature based on the natural system has never been reported. We propose a concept of bio-inspired ‘conformation-controlled surface catalysis’ analogous to the biological catalyst, an enzyme, which is useful for production of new nanocarbon materials. We demonstrate the two-zone chemical vapor deposition of the ‘Z-bar-linkage’ precursor, which represents two terphenyl units that are linked like a ‘Z’, exhibiting a flexible geometry that allows it to adopt chiral conformations with height-asymmetry on a Au(111) surface, resulting in the efficient formation of acene-type graphene nanoribbons. These cascade reactions include the production of self-assembled homochiral polymers with a planar conformation, followed by efficient stepwise dehydrogenation via a conformation-controlled mechanism. Keywords: Biomimetics / Bio-Inspired Surface Catalysis / Homochiral Polymerization / 2-Zone Chemical Vapor Deposition / Graphene Nanoribbons |
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| Superhydrophobic Materials Inspired by Porcupinefish | Masanobu NAITO |
| <Abstract> Superhydrophobic materials with micro/nanotextured surfaces are of great interest for applications such as self-cleaning, antifouling, anti-icing and corrosion protection. Such micro/nanotextured surfaces are the key to high water repellency. However, such textures are brittle and can be easily damaged if the material is deformed, scratched, or cut away. Therefore, the challenge is to develop superhydrophobic materials that can maintain high water repellency even after experiencing such mechanical deformation and damage. Here, we report a superhydrophobic flexible material with a porcupinefish-like structure, which is resistant to abrasion/scratching/slicing/droplet impact/bending/twisting, based on a composite of ZnO and poly(dimethylsiloxane) in micrometer-scale tetrapod geometry. Keywords: Superhydrophobic / Durability |
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| Polymer Science and I: A Personal Account |
| What I Learned from Alkyl Chains | Satoru INOUE |
| <Abstract> In 2015, the author, who specialized at that time in the development of organic electronics materials, published an essential paper that revealed the effect of alkyl chain length dependence on layered crystalline organic semiconductors. In this paper, the author introduces the history of the development while looking back on the author’s experience. |
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| Front-Line Polymer Science |
| Recent Acyclic N-Vinylamide | Hiroharu AJIRO, Hiroaki YOSHIDA |
| <Abstract> Recent research about acyclic N-vinylamides is reviewed. The reported polymerization control approaches are introduced, using an organotellurium compound and RAFT reagents. The current functional gels with N-vinylamides are introduced, focussing on the telechelic crosslinkers, physical gels, and the crosslinkers bearing both methacrylate and N-vinyl moieties. The surface modification of particles using poly(N-vinylamide)s are also introduced, for the biocompatibility and the interaction with biomolecules. The nanogels and microgels using N-vinylamides and the successive hydrolysis to convert to polyvinylamine are also mentioned. Recent applications with poly(N-vinylamide)s are also discussed. It is known that the cationic moieties are available for the capture of carbon dioxide, so the polyvinylamine functions after the hydrolysis of poly(N-vinylformamide) are employed. Some recent research on the separation of carbon dioxide and nitrogen are introduced, as well as the metal ion capture capabilities. The copolymers were also used for various drug delivery systems. Finally, the recent studies on the possible use for the inhibition of gas hydrate are summarized. Keywords: Acyclic / N-Vinylamide / Polyvinylamine / Polymerization Control / Gel / Drug Delivery System / Carbon Dioxides Capture / Gas Hydra |
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| Polymer Select |
| Research on Elastomer Based Composite Materials and Their Future Development | Toshio NISHI |
| <Abstract> World trend, domestic development, collaboration with industry, from tire to elastomeric seismic-protection isolators, international standardization, and their future development of elastomers and elastomer based composite materials are presented based on the author’s experience and viewpoints. In the future, advance on polymer nanotechnology and its application to polymer megatechnolgy for the society will become very important. Keywords: Natural Rubber / Elastomer Based Composite Materials / Polymer Nanotechnology / Super Fuel Efficient Tire Materials / Elastomeric Seismic-protection Isolators / Polymer Megatechnology / International Standardization |
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