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Mayumi Group

Associate Professor MAYUMI, Koichi
Research Associate ODA, Tatsuro
Project Research Associate HASHIMOTO, Kei

Research Subjects

  • Toughening mechanism of tough polymeric materials
  • Structure of multi-component polymer and soft matter systems by small-angle neutron/X-ray scattering
  • Dynamics of multi-component polymer and soft matter systems by quasi-elastic neutron scattering

The research goal of our group is to reveal molecular mechanisms for macroscopic properties of soft matter systems. One of our targets is to understand toughening mechanisms of polymeric materials. Recently, the fine control of nano-structure has improved significantly the mechanical toughness of polymer-based materials. The tough polymeric materials are expected to be applied for biomaterials, soft robots, and structural materials for automobiles and airplanes. We study nano-structure and dynamics of the tough polymeric materials by means of small-angle and quasi-elastic neutron scattering measurements with deuterium labelling. The deuterium labelling technique enables us to observe separately each component in multi-component systems. By combining the nano-scale structure/dynamics measurements, macroscopic mechanical tests, and molecular dynamics simulations, we aim to establish molecular understandings of toughening mechanisms for polymeric materials and discover novel molecular designs for tough materials.

We have developed self-reinforced gels in which polymer chains are crystallized under stretching. The crystalline domains disappear immediately after the strain is released. The reversible strain-induced crystallization simultaneously realizes high toughness and rapid recoverability under repeated deformation.
When we stretch a pre-notched specimen of a conventional polymer gel, the crack propagates immediately and the sample is broken. For the self-reinforced gel, the strain-induced crystallization of polymer chains near a crack tip suppresses crack propagation.

Publications and Research Highlights