Article
Chemistry, Multidisciplinary
Glendimar Molero, Cong Liu, Zewen Zhu, Qihui Chen, Suzanne R. Peterson, Pavan Kolluru, Hung-Jue Sue, Shuntaro Uenuma, Koichi Mayumi, Kohzo Ito
Summary: The fracture behavior of polyrotaxane (PR)-modified poly(methyl methacrylate) (PMMA) was investigated. By adding only 1 wt % of PR to the PMMA matrix, substantial improvement in fracture toughness was achieved while maintaining modulus and transparency. The interaction between PR and PMMA contributes to higher molecular mobility and enhanced molecular cooperativity, leading to the formation of massive crazing and improved fracture toughness.
Article
Polymer Science
Naoki Ando, Shuntaro Uenuma, Hideaki Yokoyama, Kohzo Ito
Summary: In this study, we investigated the disassembly mechanism of a pseudo-polyrotaxane nanosheet (PPRNS) upon heating. The results showed that the PPRNS exhibited structural changes in two temperature ranges due to the anisotropy of the topological constraint.
Article
Chemistry, Multidisciplinary
Takako Noritomi, Lan Jiang, Hideaki Yokoyama, Koichi Mayumi, Kohzo Ito
Summary: A high-yield one-pot synthesis of polyrotaxane (PR) with controllable hpCD threading ratios is reported in this work. The hpCD threading ratio of the PRs can be controlled over a wide range by tuning the hpCD concentration in the pPR solutions.
Article
Materials Science, Multidisciplinary
Yuga Taniguchi, Thanh-Tam Mai, Masashi Yamaguchi, Katsuhiko Tsunoda, Kenji Urayama
Summary: The Mullins effect refers to the phenomenon in which the stress in elastomer/filler composites decreases significantly during unloading or second loading. This study investigated the Mullins effect in carbon-black reinforced elastomers by measuring mechanical stresses and electrical conduction under different biaxial stretching. The results showed that small equibiaxial strain caused a significant increase in electrical resistivity, indicating the breakdown of the initial conductive carbon-black network. The residual destruction of the carbon-black network increased with biaxial strain for small deformations, but saturated at large deformations.
ACS APPLIED POLYMER MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yan Su, Zaoming Wang, Alexandre Legrand, Takuma Aoyama, Nattapol Ma, Weitao Wang, Ken-Ichi Otake, Kenji Urayama, Satoshi Horike, Susumu Kitagawa, Shuhei Furukawa, Cheng Gu
Summary: This article introduces a method for synthesizing hypercrosslinked polymer gels from a tetrahedral monomer through thermal induced polymerization, and studied the porosity and mechanical stiffness of the gels. The potential applications of these gels in molecular separation systems are also demonstrated.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Polymer Science
Ryosuke Osumi, Tomohiro Yasui, Ruito Tanaka, Thanh-Tam Mai, Hideaki Takagi, Nobutaka Shimizu, Katsuhiko Tsunoda, Shinichi Sakurai, Kenji Urayama
Summary: This study investigates the hardening mechanism of elastomers under tensile deformation, finding that crack propagation velocity increases with stretch and leads to crystallization-driven hardening; the characteristics of crack tips also undergo significant changes during this process.
Article
Polymer Science
Takuma Aoyama, Kazuaki Kato, Kenji Urayama
Summary: Polyrotaxane gels with low ring densities have sliding figure-of-eight cross links that can increase the network strand length in the loading direction, enhancing the ultimate elongation of the gels. This enhancement is more pronounced in uniaxial stretching and becomes more sensitive to loading axiality as the ring densities decrease.
Article
Biology
Xiyang Sun, Yingtao Liu, Chang Liu, Koichi Mayumi, Kohzo Ito, Akinao Nose, Hiroshi Kohsaka
Summary: This study proposes a neurochemical model based on physical measurements to study locomotion in soft-bodied animals and soft robot engineering. The study characterizes the kinematics and biomechanical properties of Drosophila larvae and develops a mathematical model that accurately reproduces experimental observations.
Article
Polymer Science
Masayuki Saito, Kohzo Ito, Hideaki Yokoyama
Summary: The structure-property relationship of ultrathin films of polystyrene-b-polyisoprene-b-polystyrene (SIS) is established in this study, and the effects of film thickness and strain rate on mechanical properties are investigated.
Article
Polymer Science
Ahmed Fouad Abdelwahab Mohammed, Mahmoud H. Othman, Toru Taharabaru, Khaled M. Elamin, Kohzo Ito, Masamichi Inoue, Mahmoud El-Badry, Khaled I. Saleh, Risako Onodera, Keiichi Motoyama, Taishi Higashi
Summary: In this study, folate-appended polyrotaxanes (Fol-PRX) were developed to stabilize CDE/siRNA polyplex, which enhanced the in vivo antitumor activity of the polyplex after intravenous administration. The intermolecular connection of the polyplex with Fol-PRX provided movable folate moieties on the surface, suggesting their utility as the dual-functional materials for systemic delivery of siRNA polyplexes.
Article
Polymer Science
Kenichi Inoue, Tsuyohito Ito, Yoshiki Shimizu, Kohzo Ito, Kazuo Terashima
Summary: This study demonstrates a new type of cross-linking-filler composite material that achieves both flexibility and thermal conductivity through covalent bonds between the filler and polymer chains. The composite material, fabricated using functionalized hexagonal boron nitride fillers and slide-ring polymers, reduces the use of cross-linking agents and exhibits high flexibility.
Article
Chemistry, Multidisciplinary
Soichiro Hiraiwa, Thanh-Tam Mai, Katsuhiko Tsunoda, Kenji Urayama
Summary: This study reveals the strain hardening due to strain-induced crystallization (SIC) in both cross-linked natural rubber (NR) and its synthetic analogue (IR) under planar extension. The research shows that evident strain hardening due to SIC is observed in both stretching and constrained directions when the stretch exceeds a critical value. The study also finds a distinct minimum in the nominal stress ratio as a function of stretch, indicating a reversed relationship between the increment of stress in the stretching and constrained directions. Furthermore, the investigation provides valuable insights for predicting the mechanical response of SIC rubber under different deformation conditions.
Article
Chemistry, Multidisciplinary
Javier Troyano, Fuerkaiti Tayier, Phitchayapha Phattharaphuti, Takuma Aoyama, Kenji Urayama, Shuhei Furukawa
Summary: This study presents a self-gelation approach based on metal-organic polyhedra (MOPs) that allows for the reversible assembly into nanoparticles and colloidal gels through charge manipulation. Furthermore, the simplicity of this method is demonstrated by synthesizing MOP-based gels via a one-pot synthetic approach. The research highlights the potential application of charge manipulation in the formation of supramolecular gels and porous aerogels based on MOPs.
Article
Chemistry, Physical
Atsushi Yamamoto, Takumi Inui, Daisuke Suzuki, Kenji Urayama
Summary: We investigated the yielding behavior of dilute poly(N-isopropyl acrylamide-co-fumaric acid) (PNIPAM-FAc) colloidal gels obtained above the volume phase transition temperature. We found that yielding occurs when the applied strain exceeds a specific threshold, requiring a finite, stress-independent delay time. This behavior is distinct from previous findings on delayed yielding in other colloidal gels.
Article
Chemistry, Physical
Takuro Kimura, Takuma Aoyama, Masaki Nakahata, Yoshinori Takashima, Motomu Tanaka, Akira Harada, Kenji Urayama
Summary: Supramolecular hydrogels utilizing host-guest interactions exhibit significant stress relaxation and viscoelasticity. The stress relaxation process and finite equilibrium stress are inseparable from the time and strain effects. The detachment dynamics of the transient bonds in these gels are highly sensitive to the deformation type.