What happens at fluid interfaces?

Lucio Isa

Copyright Lucio Isa 2016.

Professor Dr Lucio Iso, head of the Laboratory for Interfaces, Soft matter and Assembly in the Department of Materials at ETH Zurich, answers our questions about his research and where he believes the field is heading.

What research projects are you and your group currently working on?

We work in experimental soft matter physics, with a specific focus on colloidal particles and interfaces. Regarding the latter, we target two main aspects. On one hand, we investigate the behavior of colloidal particles during their adsorption at a fluid interface (e.g. between oil and water) and characterize their structural, dynamical and mechanical behavior after they are confined within the interface. On the other hand, we study how we can tune the macroscopic properties of soft matter systems (particle suspensions, emulsions, etc.) by tuning the properties of the interface between particles and their surroundings, e.g. by changing their shape, surface topography or chemistry.

More specifically, we work on the following aspects.

1) We study the adsorption and the dynamics of individual colloids at oil-water interfaces using a range of microscopic tools, including optical, atomic force and cryo-electron microscopy.

2) We study the behavior of colloidal monolayers as model materials to study their structural and dynamical response to localized mechanical perturbations.

3) We study how microscopic particle properties (e.g. friction) affect the macroscopic rheological properties (e.g. shear thickening) of concentrated particle suspensions.

4) We fabricate novel colloidal particles of programmable shape and composition by exploiting their assembly at a water-air interface over a topographical template.

5) We harness, control and tune the microstructure of colloidal monolayers at a fluid interface to be used as patterning tools to nanostructure surfaces.

What motivated you to pursue this field of research?

A combination of chance and persuasion! I was completing my studies in Nuclear Engineering and I was deeply attracted by theoretical studies. At the time, I was about to start a Master thesis in plasma physics when I took a course in Statistical Physics by Professor Roberto Piazza at the Milan Polytechnic. The subject fascinated me and he convinced me to do a short theory project in his group. When that ended, he persuaded me to do a short numerical project on the same topic (thermal diffusion in colloidal suspensions). By the end of it, I was doing experiments and realized that this was actually the part that I liked the most!

From that time on, I was hooked, and continued in this field. The key reason why I fell in love with the soft matter physics is that this is a field where someone with good ideas can still make a big difference on his or her own. I realized that I could think about an experiment, set it up, and do it and that at the end I would have found out something new and interesting. This is very different from other fields of physics where significant advancement requires the concerted efforts of very large teams of people and gives me a lot of motivation in my day-to-day work.

Where do you think the field is heading?

There are many exciting directions in which this field is moving, but my personal favorite concerns the future fabrication of miniaturized autonomous machines, or micro-robots, as they are sometimes called. This would be objects that are constructed to sense an environment, spontaneously react to it and autonomously perform a specific task for which they have been designed. Robotics has made enormous progress recently, and with a continuous strive for miniaturization of devices, e.g. in the medical field, “machines” start to enter the size range characteristic of soft matter systems, where thermal fluctuations, colloidal forces and surface effects become crucial. On the other hand, soft matter physicists and chemists have attempted to increase the complexity of colloidal systems to design and produce functional materials able to perform a range of tasks, e.g. self-propulsion, targeted binding and stimulus responsiveness. We are now at a very exciting time, where these two disciplines are starting to come together, holding tremendous potential for the future.

What do you find to be the most rewarding aspect of your job?

There are two aspects that are particularly rewarding. The first one is seeing one’s ideas become reality. There is nothing more rewarding in our job to construct an experiment (or a calculation) and turn an intuition into a fact. These moments do not happen often, but they are priceless. The other aspect concerns teaching. It is fantastic to see that I have been able to transmit a concept to students and that they have made it theirs. Inspiring students and passing knowledge is one of the privileges of working in science.

If you were a young physicist just starting out today, what would you study?

Not to blow my own trumpet, but I would still study soft matter. The field is so diverse and dynamic that I’m sure there is still plenty of exciting research to do in the next fifty years. If given the possibility though, I would study more chemistry.

Tell us an interesting fact about yourself.

I always cycle to work, no matter the weather. One of my fondest bike-commuter memories is when I overtook the bus to campus which was stuck in the snow going up the hill. The fresh air and the exercise make me think, and I have come up with some of my best ideas while pedaling to work!

Read Lucio’s latest research on contact angles at fluid interfaces in JPCM.

CC-BY logoThis work is licensed under a Creative Commons Attribution 3.0 Unported License. Author image provided by Lucio Isa. Copyright Lucio Isa 2016.

Categories: Journal of Physics: Condensed Matter

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