Kohzo Ito

Most tough hydrogels are reinforced by introducing sacrificial structures that can dissipate input energy. However, because the sacrificial damage cannot rapidly recover, the toughness of these gels drops substantially during consecutive cyclic loadings. We propose a damageless reinforcement strategy for hydrogels using strain-induced crystallization. For slide-ring gels in which polyethylene glycol chains are highly oriented and mutually exposed under large deformation, crystallinity forms and

The present review article deals with recent novel studies on the preparation and application of polyrotaxanes comprised of cyclodextrins (CDs) and various linear polymers, especially poly(ethylene glycol) (PEG). First, a brief introduction of the historical background of the pioneering work on the preparation of an inclusion complex and polyrotaxane is provided. Subsequently, the authors have focused on the recently developed solvent systems for the polyrotaxane. These new solvents are interest

Gels with high mechanical performance have attracted great interest because of their potential biomedical applications. Tough gels reported thus far usually contain sacrificial species to dissipate energy, thus compromising the fatigue resistance. In this study, highly stretchable and recoverable gels can be achieved by cross-linking cyclodextrin (CD)-based polyrotaxane with a low host coverage, synthesized via a one-pot enzymatic end-capping reaction with 90% yield and ∼2% CD coverage (PR02). T

ABSTRACT A novel type of gel, called a topological gel, has been recently developed with a supramolecular architecture with topological characteristics. In the topological gel, polymer chains with bulky end groups are neither covalently crosslinked as in chemical gels nor attractively interacting as in physical gels but are topologically interlocked by figure‐eight shaped crosslinks. Hence, these crosslinks can pass along the polymer chains freely to equalize the tension of the threading polymer

The demand for mechanically robust polymer-based electrolytes is increasing for applications to wearable devices. Young's modulus and breaking energy are essential parameters for describing the mechanical reliability of electrolytes. The former plays a vital role in suppressing the short circuit during charge-discharge, while the latter indicates crack propagation resistance. However, polymer electrolytes with high Young's moduli are generally brittle. In this study, a tough slide-ring solid pol

A novel "sliding graft copolymer" (SGC), in which many linear poly-ε-caprolactone (PCL) side chains are bound to cyclodextrin rings of a polyrotaxane, was prepared by ring-opening polymerization of ε-caprolactone initiated by hydroxyl groups of the polyrotaxane. An amorphous, flexible, and sufficiently tough elastomer film was prepared by crosslinking the obtained SGC-a supramolecule possessing a number of mobile side chains-with hexamethylene diisocyanate (HMDI).

A dielectric elastomer actuator with excellent electromechanical performance was fabricated by incorporating modified barium titanate into slide-ring materials with necklace-like molecular structure.

Slide-ring (SR) gels are polymer networks with movable cross-links that are prepared by cross-linking polyrotaxane (PR) in which many cyclic molecules are threaded into a linear polymer chain. The elastic modulus E of SR gels shows a unique dependence on cross-linking density: at a high cross-linking density, E decreases with increasing cross-linking density. This tendency is not in agreement with conventional rubber elasticity theory. In order to explain this abnormal dependence, we propose a n

In this study, we investigated the molecular dynamics of polyrotaxane (PR), composed of α-cyclodextrins (CDs) and a poly(ethylene glycol) (PEG) axial chain, in solution by means of quasi-elastic neutron scattering (QENS) measurements and full-atomistic molecular dynamics (MD) simulations. From QENS experiments, we estimated the diffusion coefficients of CD and PEG monomers in PR, which are in quantitative agreement with those obtained by MD simulations. By analyzing the simulation results, we su

Stiff yet recoverable water-containing materials can be found in many biological tissues including tendons, cartilages, and skins. However, it remains a challenge to develop hydrogels as load-bearing materials where high stiffness and toughness, as well as fast recoverability, are required. Making framework more compact with more rigid chains could make a gel stiffer but also restrict its recovery for lower chain mobility. Here, we report a rigid yet recoverable hydrogel by incorporating polyrot