SCHOOL OF ENGINEERING, TOHOKU UNIVERSITY Driving Force THE POWER TO MAKE TOMORROW INTERVIIEW REPORT
SCHOOL OF ENGINEERING, TOHOKU UNIVERSITY Driving Force THE POWER TO MAKE TOMORROW INTERVIIEW REPORT

Exploring new possibilities for colloidal particles by adding a perspective of physics to knowledge of chemistry.

Assistant Professor
Department of Chemical Engineering
Graduate School of Engineering,
Tohoku University
Kanako Watanabe REPORT #35

© School of Engineering, Tohoku University

A world’s first: discovering the motion of microparticles confined inside egg-like particles by external electrical fields.

If we can freely change the color of our living room walls, from green today to red another day, with a flick of a switch depending on our mood... There is a young researcher studying colloidal particles with such a vision in mind. Her name is Dr. Kanako Watanabe, an assistant professor at the Department of Chemical Engineering of the Graduate School of Engineering at Tohoku University.

Assistant Professor Watanabe studies the development of materials using colloidal particles, including nanoparticles. Her research is about designing stable materials of nanoparticles. Nanoparticles have various properties such as optical, catalytic, and sensing properties, but they are unstable and difficult to handle. She says, "When we just add salt to particles in water, they become an aggregated cluster. The same thing happens even when an external force such as heat is applied, and this material has been called "a futuristic material that’s difficult to practical use”. She then has focused on egg-like particles which are a kind of hollow-structured particles. "I thought, outer shells would act as barriers to protect the nanoparticles inside. Egg-like particles had already been reported, but their shapes and sizes are very hard to control. In our research field, the uniformity of shape and size is important to ensure uniformity of function and stability,” she explains.

First, Assistant Professor Watanabe had to establish a method for creating uniform and stable egg-like particles, which she did during her senior year at the Department of Applied Chemistry, Chemical Engineering and Biomolecular Engineering of the School of Engineering at Tohoku University. She continued her research on egg-like particles in her master’s program. She discovered that when a cluster of egg-like particles is under an external stimulus such as electricity, the motion and arrangement of particles confined inside the egg-like particles change. "While it is common that properties of a single material is limited to one property, I thought we can derive a variety of properties from an assembly of egg-like particles depending on the type and intensity of the stimulus.” she says. She then started to investigate why the motion of particles inside changes under an electric stimulus.

By incorporating physics, the efficiency of researching egg-like particles improved.

To understand the secrets of particle motion inside egg-like particles, Assistant Professor Watanabe chose Utrecht University in the Netherlands to conduct collaborative research. "I look at particles from a chemistry perspective, while my co-researchers at Utrecht University look at them from a physics perspective. They use theoretical calculations and simulations in conducting research. Chemistry researchers including me make a hypothesis, design experiments which can verify the hypothesis, and conduct those experiments; while physics researchers think about how phenomena obtained from experiments can be explained by existing theories. Collaborating with them was a breath of fresh air for me; while I had thought that conducting experiments was what guided us to and was the only way to find the truth, discussions with them made me realize that conducting experiments was not the only way.

After studying at Utrecht University for two years, Assistant Professor Watanabe’s research style has changed. She discusses what kind of experiments will efficiently get results with physics researchers first, and then conducts experiments under those conditions. She says,"My research style has become significantly more efficient. Having said that, if I only conduct targeted experiments, I might miss something important. New insights could be obtained from experiments that might come to nothing. I would like to continue to value these sensitivities as a chemistry researcher."

Her research on egg-like particles was initially motivated by the development of a material that can change the intensity of light depending on the strength of an electric field. Now that it is possible to control the motion of particles confined in an egg-like particle using the external stimulus, what developments will come out of this research? And what issues will such developments have? She says, "It would be interesting to develop a material in the future wherein egg-like particles are placed in windows, allowing ultraviolet light to pass through or not with a flick of a switch, or being able to change the color of a wall by changing wavelengths of light. The challenge of this is developing a process for mass synthesis. The process for creating egg-like particles is complicated, and simply multiplying what’s at the lab scale will never work. The role of chemical engineering is creating blueprints for the development of materials. By designing the material type and size of an egg-like particle and the motion range of the particles inside in detail, the development and application of egg-like particles will be possible. Thus, I’d like to explore opportunities to collaborate with researchers in material science in the future.

School of Engineering, Tohoku University Driving Force, The Power to Make Tomorrow. INTERVIIEW REPORT

From a technical college to the School of Engineering. The fun of experiments kept her motivated.

After graduating from Department of Design and Computer Applications, the National Institute of Technology, Sendai College, she transferred to the Department of Applied Chemistry, Chemical Engineering and Biomolecular Engineering of the School of Engineering at Tohoku University. When she entered the college, her dream was to become a designer or magazine editor. However, she gave up those dreams when she saw the exceptional design skills of the students around her. "The major 'Information Design’ was divided into the design side and the information side, and by process of elimination, I chose the information side. That’s where I encountered chemistry. For my graduation thesis in the college, I worked on a simulation of the diffusion of chemical substances which was surprisingly interesting, so I decided to transfer to the School of Engineering to study chemistry in a wider environment of a university, she says."

She also says she was not very good at chemistry. She had to relearn chemistry slowly and carefully during the first two years after transferring to university. Looking back, she says, "I was panicked at a chemical engineering class in English taught by an American professor. I did not understand anything. My score on a quiz of the class was almost zero. Despite this, what kept her going was the fun of experiments, which is the foundation of chemistry. "The study of chemistry in which you do experiments with your own hands and see reactions with your own eyes is completely different from the kind of chemistry taught in a classroom. Experiments gave me a sense of ownership – that chemistry is a subject that I can be a part of, and this makes me excited," she explains.

After graduating from the School of Engineering, Assistant Professor Watanabe proceeded to the Graduate School of Engineering. After completing her master’s and doctoral programs, she steadily built her career, including studying at Utrecht University as an Overseas Research Fellow of the Japan Society for the Promotion of Science. In 2019, she received the JSPS Ikushi Prize from the same Society for her research entitled "Control Over the Spatial Distribution of Particles via Applying External Stimuli." Moreover, in the same year, she also received the L'Oréal-UNESCO Japan Fellowship Award, and in 2023, she received an Honorable Mention from the 29th Aoba Foundation for the Promotion of Engineering Awards. She says, "No matter how good research is, nothing happens if I cannot show my research to others. I think these awards are a good opportunity for me to make my research also known to non-researchers."

You don’t have to be the person the society wants you to be. You can just be the person you want to be.

"What surprised me at Utrecht University was that there were many female researchers," says Assistant Professor Watanabe. She explains, "More than half of the graduate students are women. They have a strong sense of gender equality, and the women are very strong. They don't think about being pretty or elegant for others – socially independent women are highly valued. Surely, Japan will also have such a society someday, where it's normal for both men and women to work and raise children. My experience of studying abroad encouraged me."

Assistant Professor Watanabe and her partner, a Dutch assistant professor in the same lab, give English lessons to their students. She says, "In the Netherlands, they spoke Dutch when the Dutch people were talking to each other, but the moment I joined the conversation, they immediately switched to English. Now how about Japan? Don't you think people who come to Japan must speak Japanese? If we are aiming for internationalization in the truest sense of the word, we want all students to be able to communicate in English, so we offer the English lessons. The students' English level got improved a lot by hour-long lessons once a week; they don't feel scared of speaking English anymore."

According to Assistant Professor Watanabe, she enjoys interacting with students so much that education is her purpose in life. "The students are very smart – for example, if I suggest for 'one,' they respond with a ten. Maybe because they haven't experienced neither failure nor success, when I suggest something, they develop their idea beyond my suggestion. It is fun to realize that there's more than one way to think about something by discussing with each other. The professor who mentored me let me do my research freely, so I would like to do the same for my students, valuing their originality and just letting them take the initiative," she says.

She also says that the interesting thing about engineering is "what you design and make actually becomes a thing you can see." She explains, "The good thing about Tohoku University is that we have a lot of freedom in our research. In terms of the university's research environment, if we want to do something, we often have the equipment to support what we want to do. The teacher-student ratio is small, and we can provide an environment where mentoring is done carefully and thoughtfully. You don't have to be the person the society wants you to be – you can just be the person you want to be. I want to show students that even if they are different from others, they can follow the path they believe in. I want them to realize there are different ways to live their lives, ways that may broaden their potential."