Koichi Mayumi 교수

We studied the stress-strain relation of model dual cross-link gels having permanent cross-links and transient cross-links over an unusually wide range of extension ratios λ and strain rates ϵ̇ (or time <i>t</i> = (λ - 1)/ϵ̇). We propose a new analysis method and separate the stress into strain- and time-dependent terms. The strain-dependent term is derived from rubber elasticity, while the time-dependent term is due to the failure of transient cross-links and can be represented as a time-depend

Polyrotaxane is a necklace-like supramolecule in which many cyclic molecules are threaded into a single polymer chain and can be cross-linked to produce functional polymeric materials. The resulting materials have movable cross-linking giving unique properties different from other polymer networks with fixed covalent bonds gaining much attention for new films, elastomers and coatings. Polyrotaxane and Slide-Ring Materials is the first book to cover the fundamentals and applications of these mole

Slide-ring (SR) gels cross-linked by ring molecules are characterized by softness (low Young's modulus), elasticity (low hysteresis loss), and toughness (large fracture energy). In this article, the mechanical and fracture properties of SR gels are reviewed to clarify the physical understanding of the relationship between the molecular-level sliding dynamics of the slide-ring cross-links and macroscopic properties of SR gels. The low Young's modulus and large fracture energy of SR gels are expre

In this study, molecular dynamics (MD) simulations were carried out on the uniaxial deformation of slide-ring (SR) networks with slidable cross-links to understand the relationship between the sliding of the cross-linking points and the Young's moduli of SR gels, which are lower than those of covalently cross-linked gels with the same cross-linking densities. The slidability of the cross-links in SR gels was characterized by the rate of change of the segment number between the cross-links, <i>N<

Rotaxane is a topological supramolecule in which a ring molecule is threaded onto an axial chain. A unique feature of rotaxane is that the ring can slide along the chain. In this study, we investigate the sliding dynamics of a ring along an axial polymer in rotaxanes with different ring sizes and axial chain conformations using coarse-grained molecular dynamics simulations and considering the effect of the axial-chain fluctuation on the sliding motion. When the inner diameter of the ring is smal

The concentration-induced conformational change in hydroxypropylated polyrotaxane (H-PR) composed of poly(ethylene glycol) (PEG) and hydroxypropylated α-cyclodextrins (CDs) was investigated at various concentrations from the overlap concentration c* to the semidilute regime by using the small-angle neutron scattering technique. We employed the generalized Zimm plot with the wormlike chain model to analyze the scattering functions of H-PR since they deviated from the Ornstein−Zernike equation par

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTMechanically Interlocked Structure of Polyrotaxane Investigated by Contrast Variation Small-Angle Neutron ScatteringKoichi Mayumi†*, Hitoshi Endo‡*, Noboru Osaka‡, Hideaki Yokoyama†, Michihiro Nagao§⊥, Mitsuhiro Shibayama‡, and Kohzo Ito†View Author Information† Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan‡ Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kas

The control of the rheological properties of carrageenan gels from hierarchical structure design is very important for food and biotechnological applications. In this study, the viscoelastic properties from linear to nonlinear regimes and temperature-dependent spatiotemporal hierarchical structure of κ-(KC), ι-(IC) carrageenan gels, and their mixtures (KCIC) were investigated using dynamic rheology, small-angle neutron scattering (SANS), dynamic light scattering (DLS), and pulsed nuclear magneti

In this work, we report a high-yield one-pot synthesis of polyrotaxane (PR), composed of (2-hydroxypropyl)-α-cyclodextrin (hpCD) and polyethylene glycol (PEG), with well-defined hpCD threading ratios controllable across a wide range from 0.64% to 10%. In hpCD/PEG aqueous solutions, hpCDs are well dispersed and threaded spontaneously into hpCDs to form a pseudo-PR (pPR) structure. The homogeneous dispersion of hpCDs results in a well-defined threading ratio of hpCDs on PEG, which is suggested by