Saki Kusakabe

PhD student

The University of Tokyo

Saki Kusakabe is a 2nd year Ph.D. student in the department of Bioengineering at the University of Tokyo. She received her B.E. in Precision Engineering in 2020, and her M.E. in Bioengineering in 2022 from the University of Tokyo. Her research deals with composite materials consisting of polymers and nanoparticles. It mainly focuses on understanding the hierarchical relation between the macroscopic properties and microscopic dynamics of polymer/nanoparticle composite materials. The goal of her research is to enable the efficient design of functional polymeric materials, particularly for biomedical applications. She was selected for the WINGS-GLAFS program offered by the University of Tokyo, and was awarded JSPS DC1 Research Fellowship in 2022 – 2025. Her passion is to contribute to the physical, mental and spiritual well-being of the people. Aside her research, she has studied public health, gerontology and enjoys practicing yoga.

Phase Behavior and Dynamics of High Molecular Weight PEO/Silica Nanoparticle Composites

By adding nanoparticles to polymers, the material shows various properties, such as improved viscoelastic, optical and thermal properties. The versatile property of such polymer nanocomposites (PNCs) makes the material a promising candidate for a wide range of application in the biomedical field, including implants, wound dressing, and disease diagnostics. PNCs have a hierarchical structure, where the nano- and micro-scale dynamics influences the macroscopic material properties. To efficiently design a material with desired properties, it is important to understand the structure-property relation of PNCs. However, the quantitative relation between the microscopic dynamics and macroscopic property is not clear, especially when the polymer size is larger than the particle size. Our study aims to systematically understand the relation between the macroscopic property and microscopic dynamics of PNCs. This research specifically focuses on the macroscopic phase behavior and the underlying microscopic dynamics of PNCs when the polymer is larger than the particle. We employed a composite consisting of simple-structured components: poly(ethylene oxide) (PEO) and spherical silica nanoparticles. The structural simplicity allows an in-depth understanding of the physical laws governing the behavior of PEO/silica composites, which can be further extended to PNCs with complex structures. Quantitative evaluations of the macroscopic property and microscopic dynamics were conducted by viscoelastic measurements, microscopic imaging and scattering tests. The results of each measurement were combined to elucidate the phase behavior at a wide range of polymer/particle concentrations and the microscopic dynamics causing such phase behavior.