POLYMERS　Vol.62　No.7
>> Chinese >> English >> Japanese >> Korean
COVER STORY
Self-Healing Materials: Recent Development and Application
COVER STORY: Highlight Reviews
Self-Healing Supramolecular Materials Akira HARADA
<Abstract> Supramolecular gels were obtained by copolymerization of cyclodextrin monomer and guest monomers or mixing cyclodextrin polymer and guest polymers in water. Even after the gels were cut in half, these gel pieces are self-healed by contacting the cut ends. When adamantane group was used, the gel strength has been recovered almost 100%. Complete self-assembly has been achieved. When the stimuli-responsive guests are used, the self-healing process can be controlled by some external stimuli, such as light and redox reactions. Macroscopic self-organization has been achieved using host gels containing cyclodextrin and guest gels. The self-assembly process can be controlled by external stimuli such as redox reactions and photo irradiation. The self-organization of gels can be also controlled by using pyrene gels and cyclodextrin gels. In this case, the gel assembly processes can be controlled by solvents. Gels, which can be extended and shrunk by light, have been obtained using gels containing cyclodextrin and azobenzene parts.
Keywords: Self-healing / Self Organization / Gel / Cyclodextrin / Host-Guest Interactions / Stimuli-Responsive / Sol-Gel Transition / Supramolecular Polymer
Top of the Page▲
Self-Healing Fiber Reinforced Polymer Kazuaki SANADA
<Abstract> Damage can cause a reduction in strength and stiffness of fiber reinforced polymers (FRPs). As a result, the structural capability of the FRP is reduced, and premature failure can result if the damage is not detected and repaired. However, damages in FRPs are extremely difficult to detect and repair by conventional methods. The current research suggests that repair of damage can be accomplished by incorporating repair components into the FRP. This novel concept is that of self-healing. The idea of a self-healing material has led to significant interest in the current literature. Many techniques have focused on the ability to heal damages in FRPs. In this paper, we present an overview of various self-healing concepts for FRPs, and recent progress and advances that have been made on self-healing of interfacial debonding in FRPs.
Keywords: Composite Material / Microcapsule / Interfacial Debonding / Self-Healing
Top of the Page▲
Healing Phenomena by Molecular Diffusion Masayuki YAMAGUCHI
<Abstract> Molecular interdiffusion of polymer chains can provide the self-healing property, which has been known for a long time as “crack or craze healing”. Such kinds of healing occur when a damaged sample is exposed to higher temperature than the glass transition temperature. This is called “thermal healing”. Further, the healing phenomenon can be observed by immersing a polymer into a specific solvent, the so-called “solvent healing”, which is attributed to enhanced mobility by plasticization. Moreover, a weak gel having a lot of dangling chains exhibits the self-healing behavior without any manual intervention because of the interdiffusion of the dangling chains. The dangling chains have to be longer than the entanglement molecular weight to show good healing efficiency.
Keywords: Entanglement Couplings / Dangling Chain / Thermal Healing / Solvent Healing / Weak Gel
Top of the Page▲
COVER STORY: Topics and Products
Development of Optically Healable Materials Using Polymer-Microparticle / Liquid-Crystal Composite Gels Takahiro YAMAMOTO, Masaru YOSHIDA
<Abstract> A novel optically healable material was developed from a microparticle/liquid-crystal composite gel containing a small amount of a photochromic azobenzene dye. The composite with appropriate particle concentrations existed in the gel state in the nematic phase owing to the formation of particle networks in the host liquid crystal. We demonstrated the photochemical repairing of a damaged section of a particle/liquid-crystal gel by the site-selective gel-sol transition induced by the photochemical modulation of the host liquid-crystal phases.
Keywords: Liquid Crystals / Colloids / Gels / Self-Assembly / Self-Repearing Materials / Photoresponsive Materials
Top of the Page▲
Self-Healing Polymer Hydrogel Kazutoshi HARAGUCHI
<Abstract> A nanocomposite hydrogel (NC gel) consisting of a unique polymer/clay network structure, can exhibit complete self-healing through autonomic reconstruction of crosslinks across a damaged interface. Mechanical damage in NC gels can be repaired without the use of a healing agent, and even sections of NC gels separated by cutting, from whichever the same or different kinds of NC gel, perfectly (re-)combine by just contacting the cut surfaces together at mildly elevated temperatures.
Keywords: Self-Healing / Hydrogel / Nanocomposite Gel / Mechanical Property / Clay / Organic-Inorganic Network
Top of the Page▲
Recyclable Rubber Material Designed with Introducing Hydrogen Bonding and its Application Takahiro OKAMATSU, Jun MATSUDA
<Abstract> Vulcanized Rubber has been used in many application such as Tires, Belts and Insulation materials. The excellent physical properties mainly depend on the network structure. However, this structure also results in the problem that recycle is not easy. Our recent R&D reveals that introducing hydrogen bonding units introducing into the rubber structure solves the trade-off relations between physical properties and recyclability of vulcanized rubber. The most effective hydrogen bonding unit was shown to consist of the maleic anhydride and heterocyclic amines, in particular, carboxylic acid and amidotriazole groups. The Stress-Strain curve of Isoprene rubber modified with hydrogen bonding units is corresponding to the sulfur vulcanized rubber, so that this technology was considered to be useful for existing markets with better recyclability. An application to the puncture-less tire for wheelchairs is shown here as a typical example.
Keywords: Thermoreversible Polymer / Hydrogen Bonding / Recyclable Material
Top of the Page▲
Scratch Resistant Clearcoats Based on Polyurethane Technology in Automotive Coatings Tomokazu SHIGEMORI
<Abstract> The wide variety of clear coatings has been adopted in automotive industry. Polyurethane clear coatings were established as one of the important technologies that achieve excellent film appearance, durability and chemical resistance. Clear coats have been required to improve not only film appearance, etch resistance but also scratch resistance. Scratch resistant clear coatings based on polyurethane technology have already entered the market. These clear coatings meet great scratch resistance caused by high cross-linked film with polyols and polyisocyanates. Polyisocyanates crosslink the polymer and have an influence to heal the scratch-damages. Especially, high functional polyisocyates are strongly effective to achieve excellent scratch resistance.
Keywords: Clear / Scratch / Automotive / Urethane / Isocyante / Functionality / Hydrogen Bond
Top of the Page▲
Polymer Science and I: A Personal Account
Crossing the Bridge Shuji FUJII
<Abstract> Looking back on how I arrived at the idea of “structural rheology”, the rheological behavior coupled with the structure change induced by the external fields. We are developing new topics in the non-equilibrium soft matter physics. Crossing the bridge explores new directions in my research topic.
Top of the Page▲
Front-Line Polymer Science
10Topics about 3D Printer for Gels and Polymers Hidemitsu FURUKAWA
<Abstract> 3D printing has attracted public attention for quite some time already in Japan. It was probably triggered by “Makers: The New Industrial Revolution”, written by Chris Anderson, translated into Japanese in October, last year. Although the author had started the development of 3D gel printing in 2009, he did not expect that such a boom would come. What is going on?
Keywords: Synthesis / Processing / UV Irradiation / Additive Manufacturing / 3D Printer / 3D Scanner
Top of the Page▲
 
Copyright(C) 2012 The Society of Polymer Science, Japan All Rights Reserved.