Science - March 10, 2011

The hard science of soft matter


Martien Cohen Stuart has turned research on soft matter into one of the most fruitful scientific fields in Wageningen. In both music and science, this distinguished professor believes in the power of cooperation. 'I love the richness of the ensemble.'

In everyday life, if you boil an egg it becomes hard. And then you don't run the risk of facing a raw or runny egg at breakfast. But in life according to Martien Cohen Stuart, there are other priorities. Making solidified proteins fluid again is exactly the kind of research project in which he has made his name.

Foam, emulsions, fluid crystals, whether or not surfaces become moist... these are topics his career has revolved around. And the overarching theme is what is known to the experts as 'soft matter': 'stuff that you can squeeze out of something' in Cohen's own pithy summary. The focus is consistently on 'the forces between molecules, the effect they have on each other'. To understand this, and their collective behaviour in particular - he even speaks in terms of 'the sociology of molecules' - is the chief quest of Cohen Stuart and his very broad-based Wageningen chair group, Physical Chemistry and Colloid Science. They do far-reaching research, even going so far as to make completely new (macro-) molecules. These are materials with a combination of characteristics, the progeny of the drawing board. Nowadays they also include dead matter combined with living matter. 'DNA is a molecule too, after all', says Cohen Stuart in explanation. To him, things that sound like science fiction to the lay person are all part of the new convergence of the natural sciences. 'It was only the chemical industry that made a separate science out of chemistry.' But isn't the blurring of the boundaries between living and dead a bit scary? 'I never look at it like that, actually', he responds a little bashfully.
Sociable musician
His day-to-day work is simply research. Very demanding research and very time-consuming too. Friends, family and colleagues all see Martien Cohen Stuart as a typical scientist. Although he does have another great passion - besides his wife Marina - and that is music. For someone who eventually decided not to go to the Conservatoire after all, he played at an extremely high level: the national youth orchestra and the Dutch student orchestra. The bassoon. 'I would recommend it to anyone,' he says with a smile, 'because the competition is much smaller than with most other instruments.' Nowadays he plays in a quintet that gives regular concerts. 'I've always been a sociable musician. I love the richness of an ensemble.'
In science too, he is no soloist. But he is certainly creative. Someone with ideas. He prefers to call them 'good intuition' or 'hunches'. And if one of those hunches, for example about synthetic polymers with positive and negative patches, turn out to be right, he enjoys one of the best moments you can have in this field. His success can be gauged by the number of PhD students walking around his department, by the collaborative partnerships it has with countries from Japan to Germany, and by the fact that he has managed to obtain almost all the big NWO (Dutch research funding body) grants. Not to mention the recent allocation of 2.5 million euros by the European Research Council.
How does Cohen Stuart do it? For a start, he has high expectations of the people he works with, without making a big issue out of it. It goes without saying that anyone who has come across a potentially interesting idea - whether at a conference or anywhere else - will come and share it with everyone else. It is an open-door culture in which people drop in on each other and bandy ideas around, accepting that half of them won't come to anything. A freedom to speak up and exchange ideas is typical Wageningen, thinks Cohen Stuart, along with the interdisciplinarity that goes with it.
Mind on his work
And Cohen Stuart is also a cogent speaker. So at performances of his quintet he is always the one who introduces the music, quoting freely from world literature from Shakespeare to Dutch epigrammatist Kees Stip. If there is research going on at the chair group on iron molecules, he will dream up a good reason for calling them 'iron ladies'. But this eloquence is something he has had to learn. 'My first six or seven grant applications didn't go too well', he says. In his early days as professor, the threat of drastic budget cuts hung over the chair group too. It felt like a heavy responsibility and it made him angry. That was the only period in which he has lost sleep over his work. The other occasion when he could not sleep well was around Christmas 2006 when his wife rapidly lost all sensation in her legs. 'Then you even took a month off work', says Marina Karsten, who is sitting with her husband by the glowing wood stove in the extension to their rambling detached house. She still walks with difficulty and has had to swap a fulltime job as head of spatial planning for Veenendaal and Wageningen (she studied in Wageningen too) for a life dominated by walking, swimming and other therapeutic activities.
Not easy, certainly not with a husband whom many describe as 'incredibly kind' and even 'sweet', but whose mind is almost always on his work. 'That was sometimes an issue for the children too', says his wife. But their two sons left home some time ago now. One studied physics, the other is studying chemistry. Their portraits grace the wall above the congenially messy bookcase. But the younger son, Diemer, says over the phone that it never bothered him that his parents worked all the time and travelled a lot. He recalls the Saturday mornings when the homely smell of his father's Friday evening pipe or cigar used to hang in the air. On Sunday mornings there was always classical music at breakfast time. 'That was a bit depressing for a kid', he chuckles.
Matière molle
He also remembers that his father loved to explain things and did it well. With lashings of enthusiasm. The same enthusiasm causes him to practically dance up and down when he give public talks about 'his' soft matter - which is also the title of the journal he edits. 'We are made up of soft matter ourselves', he observes with obvious satisfaction. And then to think that the very concept did not exist yet when he started on his old-fashioned long Dutch degree course in chemistry. It was the French Nobel prize winner Pierre-Gilles de Gennes who laid the foundations for the discipline, talking in his lab in the nineteen eighties of matière molle. Cohen Stuart: 'A bit of a double entendre, as matière molle has a sexual connotation.'
He should know: Cohen Stuart was brought up on French and France. After school he would often find his mother, ready with the proverbial tea and cookies, grading the papers that were part of her work as French teacher. And every summer the family set off from The Hague in their Citroën 2CV, Martien and his two sisters on the back seat, to go camping in France. With her French, his mother could always sort anything out with the local farmers on whose land they camped out. And he has remained a Francophile. In 2003 he and his wife bought a grange - a barn - in Normandy. Out come the photos, to go with the glass of wine that has now been poured. It is 25 metres long and nine metres high. It is surrounded by five hectares, an orchard with 100 trees. No small project. 'I go along with something like this', says his wife. 'But I don't go into it in the same carefree way as he does. And I hadn't considered the possibility that the body could cause problems. For Martien it's a case of starting on something although you don't know yet how to go about it, and trusting that you will find out as you go along.'
And that is probably typical of this scientist. In spite of his 'domestic' side - which expresses itself in his love of cooking, for example, 'preferably something different every time, a bit of experimentation - Cohen Stuart lives up to a couple of the stereotypes of the absent-minded professor. He has been known to forget appointments. And he can easily plan a trip abroad right around the time of his wife's birthday. He couldn't care less about etiquette or dress codes. In fact, this is something he is quite famous for. If his quintet had agreed to perform in black trousers or skirts with brightly coloured shirts, he was quite capable of turning up in a T shirt or lumberjack shirt. But they have managed to reform him on that point. /Liesbeth Koenen
With thanks to: Josie Zeevat (secretary), Diemer Cohen Stuart (younger son), Renske Carrière (older sister), Frans Leermakers (colleague researcher), Irene Hagenaars-Bos (quintet member) and Marina Karsten (spouse).

Martien Cohen Stuart
1948: born
Grew up in The Hague, the second of three children
1975: Master's in Chemistry at Groningen University
1976: got together with his wife, Marina Karsten, with whom he has two sons
1980: PhD in Wageningen
Has worked there since then at Physical Chemistry and Colloid Science, as professor since 1996.
2009: Research director of the Dutch Polymer Institute (DPI), one day a week
2010: awarded ERC Advanced Grant;
Membership of Royal Netherlands Academy of Arts and Sciences;
Membership of Royal Holland Society of Sciences and Humanities;
Chair of Van Uven Foundation Wageningen (which lends sheet music and instruments to students)