Until the chemistry is just right

Dübendorf, St. Gallen und Thun, 08.08.2023 - At Empa, Dorina Opris is researching how to synthesize complex electroactive polymers for robotic components, sensors or batteries – a promising project that the European Research Council (ERC) is currently funding with one of its prestigious ERC Consolidator Grants. This is not the Empa chemist’s first success – but the road that led to it wasn’t all that easy.

At first glance, the career of Dorina Opris, born in 1974, seems like a picture-book one: from studying chemistry at Babeş-Bolyai University in Cluj, Romania, to the Free University of Berlin, to becoming a titular professor at ETH Zurich and head of the Functional Polymeric Materials research group at Empa – funded by an ERC Consolidator Grant worth around two million euros. All this with a family and the joys, worries, and duties of two children.

How does this work? With talent that was recognized and encouraged early on – even as a student in Transylvania. With a diverse education – not only in theory, but also in laboratory practice, which Opris misses in some of her students in Switzerland. And thanks to a field of research with huge potential: Novel dielectric polymers stretch under electrical voltage and can be used as ultra-thin layers in actuators or other components – for example, for artificial muscles, which have been investigated for years, for power generation and much more.

But the path to this exciting discipline was no walk in the park, but rather steep and with detours. Opris’ search for a job after her daughter was born took almost two years before she was able to start at Empa. And when she started out in materials science, the trained organic chemist first had to find her field, and in some cases, even invent it – with initial setbacks. Ideas failed, research funding was not approved. How does that make you feel? “Sh…,” says Opris, laughing.

So, what do you do then?

Just go on. Support came from the Swiss National Science Foundation (SNSF) and the Sciex program for three postdoctoral fellowships, all of which Opris filled with women. And finally, in 2020, the ERC Consolidator Grant for the TRANS project (see infobox), for which the researcher worked up a sweat: two weeks of meticulous preparation for a two-minute Zoom presentation and 18 minutes of Q&A with experts. “I had to be able to answer a lot of questions very quickly,” she says, “but that suited me because I’m a person who gets to the point quickly and doesn’t make a lot of words.”

Fruitful exchange at Empa

The fact that she has mastered her field from A to Z is, as she points out, also thanks to knowhow built up by colleagues at Empa – such as engineer Gabor Kovac. He drove the manufacture of stack actuators with expandable silicone discs for many years and developed them to operational maturity with his partner Lukas Düring, until their spin-off CTsystems was recently acquired by the Daetwyler Group.

“The devices for measuring how actuators stretch in different electric fields were developed by them,” Opris says, “We were early on this topic, and that helped me tremendously.” Unlike her colleagues, however, the chemist is working not so much on the technology for printing such components, but one “floor below” – that is, on the synthesis of novel polymers suitable as non-conductive layers for stacked transistors, elastic films for power generation and other elements.

The desired profile: as thin as possible, with the long-term goal of many layers only ten micrometers thick; easily stretchable, sensitive to low current voltage, and at the same time robust. And above all: printable, meaning no solvents for the conductive layers between which the polymers lie. “Solvents can damage the polymer layer. In addition, the material would have to dry for a long time to avoid emitting harmful vapors,” explains Opris, “so we try to go without – with the right chemistry.”

Diverse requirements that researchers around the world are dealing with. Suitable compounds that raise hope are polysiloxanes, which the Empa specialist is also working on. One important advantage of these polymers is that they are relatively easy to synthesize; the chemical backbone of their strands is very mobile – and they can be specifically functionalized with polar groups, i.e. plus-minus charged molecules.

Snake-like molecules

What is difficult for laypeople to understand, Dorina Opris explains with a vivid image: “You can imagine these polysiloxanes like a pot full of snakes that constantly want to move.” The polar groups have a twofold effect on them. First, they make the molecular snakes more sensitive to electric fields, so they respond to low voltages. Second, they act like a kind of glue between the molecules; this “stiffens” them, reducing their elasticity. It is necessary to fine-tune both effects to achieve maximum success. For a practical application, the transition from the solid to the elastic state at low temperatures is important so that the technology can later be used at room temperature.

In addition, such polymer structures still have to be chemically crosslinked so that they can become elastic layers – for example, by UV light and with the help of so-called end groups: quasi-molecular “hats” that the snakes carry at their ends. But in laboratory practice, it has so far proved tricky to reliably provide these polymers with defined end groups. “That annoys me!” admits Opris with a smile.

Healthy ambition is needed for the TRANS project, which the chemist herself calls “very, very ambitious”. The team is optimistic that earlier work has already produced encouraging results; such as a polysiloxane compound that reacted to a voltage of only 300 volts and deformed strongly – an extremely low value. Printing capacitor layers without solvents has also already been achieved. And a doctoral student recently developed a piezoelectric elastomer that, when stretched, exhibits a significantly higher electrical response than other compounds currently in use.

Creativity and team spirit for success

To achieve successes that prove valuable for practical applications, of course, many more steps are needed – and the qualities that brought Dorina Opris to Empa and ETH Zurich. Not only stamina and the ability to turn failed attempts into progress, but also creating an inspiring environment for employees that allows for open debate and even mistakes so that good ideas can emerge.

And above all: optimism. Young researchers, she thinks, should be given exciting and challenging projects and then allowed to work independently to keep them motivated. Her advice to talented women based on her own biography: “Don’t wait until someone pushes you to do research. You have to be self-motivated and strong and follow through! And take a risk sometimes, too.”

Dorina Opris' career path

The researcher studied chemistry at Babeş-Bolyai University in Romania and later completed her doctorate in inorganic chemistry there and at Freie Universität Berlin. In 2006, she joined Empa’s Functional Polymers lab as a postdoc. Since 2014, she has headed the Functional Polymeric Materials research group; in 2023, she was appointed titular professor at ETH Zurich. In addition to diverse work on polymers such as polysiloxanes, she performs peer-reviewing activities with renowned publishers. Dorina Opris has also been a member of Empa’s Research Commission since 2016.

Prestigious support

With the research project “Synthesis of novel stimuli-responsive dielectric polymers and their use in powerful transducers” (TRANS), Dorina Opris is building a multidisciplinary team to develop printable dielectric polymers. They can convert one form of energy into another – be it electrical voltage into strain or motion and temperature changes into electricity. Potential applications range from actuators and sensors to soft robotics to energy storage and solid-state cooling. The project is scheduled to run for five years until April 2026. The TRANS project was selected from more than 2,500 applications to receive an ERC Consolidator Grant.

Address for enquiries

Prof. Dr. Dorina Opris
Empa Department Functional Polymers
Phone +41 58 765 4304
dorina.opris@empa.ch