Hydrophilic polymers often contain hydrophobic groups (e.g., hydrocarbons) on their repeating units, and thus can exhibit phase separations depending on temperature, salt concentration, and polymer concentration. Such phase separations can be attributed to the change of interactions between polymer chains and water molecules. In our group, we are trying to clarify the underlying mechanism of the phase separation for a given polymer by using Raman and IR spectroscopy techniques.

Precise and accurate control of polymer microstructures, such as crystalline structures, is of great importance in designing polymer-based materials. In order to provide a more in-depth understanding on the crystalline structure of polymers and its growth process, we are developing a novel technique by, for example, combining existing methods, such as AFM, Raman spectroscopy, IR spectroscopy.

We apply our expertise in Raman/IR spectroscopy to the analysis of the redox reaction of polymers with redox active groups, such as viologen and aniline derivatives. In doing so, we integrate cyclic voltammetry into Raman/IR spectroscopy to perform both electrochemical and structural analysis at the same time.

Polyelectrolytes are polymers with ionic groups on their repeating units. Although an extensive study has been provided in the past half century, our understanding on the conformation and properties of polyelectrolytes in solution is still far from complete. On the other hand, a recent research progress in polymer chemistry allows us to explore different facets in polyelectrolyte science. In our group, we study the conformation and viscoelastic properties of polyelectrolytes using polymers with ionic liquid structures.

Polymers with ionic liquid structures, called polymerized ionic liquids or poly(ionic liquid)s, are considered as promising candidates for polymer electrolytes in energy storage devices. We study the relationship between the charge transport and the polymer dynamics for polymerized ionic liquids in order to develop fast-ion-conducting polymer materials with improved mechanical strength.

Microrheology is a powerful tool to investigate high-frequency responses of polymer chains. Using diffusing wave spectroscopy technique, we investigate the entanglement dynamics of polyelectrolytes.