Kyushu University (I²CNER): Dr. Shigenori Fujikawa

In my doctoral thesis research, I have been studying organic chemical synthesis of molecules assembled into supramolecular structures under the supervision of Professor Toyoki Kunitake of Kyushu University. This research is called molecular assembly, in which various molecules are added to a solution to form an aggregate structure. One model is a tadpole-like molecular structure called a surfactant, which is an amphiphilic molecule with both hydrophilic and hydrophobic groups. When the structure of amphiphilic molecules are well designed, a very thin structure with a thickness of only about two molecules, called a vesicle, is formed, just like a cell membrane. When I was in college, I did research on fabricating vesicles through self-assembling process of molecules. Later, as I studied how to control and arrange molecules at interfaces and surfaces, I shifted to the field of thin films.

I did not always want to be a university professor. When I was a freshman in college, the economy was just booming with the bubble economy. Therefore, I was interested in industries such as banking, securities, and trading. At that time, it was common for most chemistry students to go to graduate school, and after graduation, they went to work for chemical companies. When I was in my fourth year of college, I began to question my decision to follow the same path. At that time, I consulted with Prof. Kunitake, saying that I wanted to consider other paths instead of going to graduate school.  He told me, “Graduate school is where you are trained in the methodology of finding a problem, setting it, how to tackle it, and how to appeal it to the world. Chemistry is just about using materials called chemistry, and the methodology can be used in other fields besides chemistry. I was convinced by this advice, decided to go to graduate school, and have continued on the path of the chemistry doctorate program at Kyushu University, and was assigned as a postdoctoral researcher at the Andrew Hamilton Lab at Yale University, which was famous for its molecular recognition chemistry that precisely identifies molecules using synthetic organic chemistry. I was lucky that I happened to talk to him during an international conference presentation in my third year of the doctoral course.

After one year in the U.S., Prof. Kunitake asked me to join a new project at RIKEN, and I decided to return to Japan. At that time, RIKEN had a relatively large number of people in the physics field, and I was stimulated by their different ways of thinking. When we study surfaces and interfaces, we think about molecular arrangement and structure, but the professors in the physics field were not concerned with chemical structures, but focused on the functions of surfaces and interfaces created by nanostructures in the nanosized region, which is slightly larger than molecules. It is true that my experience at RIKEN has influenced my current research.

Then, around 2010, there was an open call for researchers in CO₂ capture at the International Institute for Carbon-Neutral Energy Research (I²CNER) at Kyushu University. At that time, I was already doing research on creating the large and free-standing nanomembranes, and research at the university appealed to me, so I applied for it and was fortunate enough to be hired. Of course, my research is currently focused on CO₂, but I think it would be more appropriate to say that I am looking at CO₂ as just one of many molecules, rather than focusing solely on CO₂ separation and reduction. “Permeation” is an important function in our research on thin films. If we can precisely control the function of permeation, for example, allowing certain molecules to permeate while not allowing others to permeate, we will be able to extend our research to other fields. Separation of gases is also a difficult subject. Because of the surface tension of liquids, they do not easily leak even if there is a small hole at the micrometer level. Gases, on the other hand, can easily leak through small holes. In addition, gases are active even at room temperature, so it is quite difficult to select and separate them well. I think this is a theme that should be challenged academically, so I started by focusing on the molecule CO₂ and working on controlling its permeation through thin films.