Mending ability of network polymers with dynamic cross-links is described. The polymers are networked by thermo-reversible Diels-Alder (DA) reaction of furyl-telechelic prepolymers and tris-maleimide. Because of the moderate molecular weight of the prepolymers, the network polymer is only loosely cross-linked. The mending ability of the polymers is induced by the reversible formation of cross-links. To achieve this mechanism, two conditions are required: the molecular scission upon the material failure occurs at the DA adduct by the retro-DA reaction and the free furan and maleimide groups generated by the chains scission have mobility high enough to reform the DA adduct bridging the crack surfaces. When anthryl-telechelics is used in place of furyl-one, a tough self-mendable elastomer with higher thermal stability can be obtained.

抄録全体を表示

In the modern world, expanding the useful lifespan of materials is becoming highly desirable. Thus, self-healing and self-repairing materials should become valuable commodities. To create self-healing materials, our research focuses on the formation of supramolecular materials through host-guest interactions, which is a powerful method to create nonconventional materials. We employ CD and aliphatic groups as host and guest molecules, respectively, to construct supramolecular self-healing materials. Host-guest interactions have unique features due to selective complementary interactions, which have easily tuned material strength and self-healing efficiencies. Supramolecular materials formed by host-guest interactions recover to the initial strength even after the materials were cut in half, and then rejoined.
Moreover, we report the formation of supramolecular hydrogels and their redox-responsive and self-healing properties due to host-guest interactions. Redox stimuli induce a sol-gel phase transition in the supramolecular hydrogel and can control self-healing properties such as re-adhesion between cut surfaces.

抄録全体を表示

A new type leakage isolation sheet with self- repairing mechanism is developed, in which there is no water leakage when the sheet is broken. The sheet consists of two rubber sheets with lattices inside. Polymer particles are in the lattices, and sandwiched between the rubber sheets. The polymer particles expand in contact with water, and the pressure generated repair the broken part. It is clarified that the proposed sheet isolates leakage perfectly under 2kPa pressure when the sheet is broken by a 20mm diameter punch. The technique is applied to a tire, and a new-type tire is presented, in which there is no air leakage when nails break the tire. The broken part is repaired automatically by its self-repairing mechanism.

抄録全体を表示

The interface between the fiber and matrix has a major influence on the mechanical properties of fiber reinforced polymers (FRPs). Damages at the interface such as interfacial debonding can cause a reduction in strength and stiffness of 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, microscopic damage such as interfacial debonding is extremely difficult to detect and repair by conventional methods. The current research suggests that repair of microscopic 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 microscopic damage 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.

抄録全体を表示