Dr. Sissi de Beer


Sissi de Beer, Assistant Professor Functional Polymer Surfaces, is programme manager of 'Recovery and Circularity of Valuable Resources (ReCoVR), a consortium of companies and the four technical universities investigating how specific molecules can be filtered out of waste streams for greater circularity. 

As a PhD student she focused friction research on surfaces. “We looked at the topology of a material with an Atomic Force Microscope (AFM) but then you don't get to know anything about the chemical composition. Later, during my postdoc, I was able to combine AFM research with spectroscopy, which did provide such information.” At the same time, De Beer encountered so-called 'polymer brushes'. She explains: “Polymers are long molecules with a certain mass and elasticity. When you attach them to a surface as a coating, they lower the friction of the surface. The effect is similar to what happens in our joints. There, sugar chains retain water, creating a kind of slippery cushion and preventing the bones to rub against each other. We tried not only to imitate these natural lubricants with polymers, but also to control their 'lubricating' properties. The friction can be turned on or off by changing the properties of the liquid between the brushes. This can even be done by applying an electric field when we use the ions in the liquid.”

Sissi de Beer

Waste contains all kinds of things, but often in low concentrations. With ReCoVR, we may be able to redeem these materials

Sissi de Beer

As assistant professor in the Materials Science and Technology of Polymers group, De Beer realized that she was missing out on an entire field by only investigating how polymer brushes behave in liquids. “We became one of the first groups to investigate the behavior of polymer brushes in air. Because these brushes attract liquids, they are also able to capture all kinds of substances from the air or from a gas," she says. “That makes them suitable for many applications. A coating of polymer brushes can filter gases or liquids from air, but it can also extract valuable molecules from waste streams, for example.”

To realise this, De Beer has been working as program manager to set up ReCoVR, a consortium of companies and the 4TUs that will broadly investigate how specific molecules from waste streams can be filtered for more circularity. “Waste contains all kinds of things, but often in low concentrations. For traditional separation methods, based on temperature and pressure, it is too expensive to separate all usable substances from waste," she says. “With electrically driven separation methods, for example with polymer brushes or other smart coatings, it is probably possible to recover very small concentrations of molecules in an energy-efficient manner.”

ReCoVR is primarily aimed at the chemical and food industry, where currently half of the costs comes from separation technologies. De Beer: “We are focusing on all kinds of molecules that you could capture with our technologies, both for the purification of water and for the recovery of molecules, such as proteins, sugars, salts, and carbon monoxide.”


When she was a student herself, contact with the researchers who taught her was crucial, says De Beer: “That fueled my enthusiasm for the field and for science. When I started teaching myself, setting up good courses and pleasant contact with the students was therefore a priority.” As a researcher, De Beer is no longer working in the lab herself. She has a supporting role, which she also sees as a form of education. “It gives me satisfaction to ensure that students and young researchers are successful,” she says. “Seeing my students flourish, makes me feel very proud.” As of the spring of 2022, De Beer is also the program director of Applied Physics. “In this role I have even more impact, because I get to participate in decisions about organizational matters,” she says. “I am actively involved in various subjects and I think it is important to keep contacts between students, lecturers and the study program warm. Together we can ensure that Applied Physics is and remains a TOP program.”

About Sissi de Beer

After her bachelor’s degree in Applied Physics in Eindhoven, De Beer came to the University of Twente for her master’s degree. She obtained her PhD at the Physics of Complex Fluids chair, after which she fulfilled postdocs in Jülich and Toronto. In 2016 she fully returned to Twente as a university lecturer. De Beer has been associate professor of Functional Polymer Surfaces since 2022 and also the program director for the Applied Physics program. She is program manager of the ReCoVR consortium, a collaboration between the four TUs and many companies, which was awarded five million euros in 2021 within the Perspectief program of NWO.

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