How big molecules conquered the world

It is almost inconceivable, but 70 years ago there were hardly any plastics at all. It was 60 years ago that this material made from polymers – long chains of repeating units – began its rapid rise. And it was exactly 50 years ago that Groningen was the first Dutch university with a separate department of Polymer Chemistry. Ger Challa was the man behind this innovation.

‘Polymers are tangible. They are big molecules but also materials that you can characterize and apply. If I encounter such a material I tap it and feel it.’ From his home in Heemstede, Challa explains what makes polymers so fascinating. He was one of the pioneers of polymer chemistry in Groningen.

Initially such large molecules were known in biology, proteins or DNA for instance, both ‘biopolymers’. There were as good as no artificial polymers in the first decades of the 20th century, but the second world war gave rise to research into new materials. ‘Even so, polymers still weren’t a proper subject when I was studying chemistry between 1946 and 1953’, says Challa. But things were set to change: TNO in Delft already had a Plastics Institute, and companies such as Algemene Kunstzijde Unie (AKU and later Akzo) and Philips had begun to invest in research.

Competition

Challa spent ten years working at the Institute for Cellulose Research at AKU in Utrecht, where he conducted research into the production of PET (Polyethylene terephthalate). He also did his PhD in the same subject at the University of Amsterdam. Just as the institute was set to move to Arnhem, Challa received an offer from Groningen. ‘That was a challenge and it appealed to me.’ So the Challa family’s removal van changed tack and travelled north instead.

Challa was appointed Professor of Chemistry and Technology of Polymers at the University of Groningen in 1964. ‘Research into polymers was always conducted in departments of physical chemistry or, as in Groningen, technical chemistry. But I wanted a separate department with its own research and teaching.’ He soon had the go-ahead from the technical chemistry department to start a polymer chemistry programme. ‘That was competition for the other programmes of course, so it was fantastic that they agreed.’

Textbook

Soon about 60 students were studying polymer chemistry, putting this programme with the big boys in chemistry. ‘Our graduates and PhD students easily found work in industry, at companies such as Akzo, DSM or Philips.’ By separating from the more application-focused Technical Chemistry, Challa could take a more fundamental route in his research. ‘Our strength was that we could make and evaluate new materials. You didn’t often see that combination.’

The chemical industry was burgeoning. New materials for all manner of applications were being discovered and brought to market. One example of Challa’s research was the formation of polymers in the presence of a ‘matrix’ of other polymers. ‘This affected the crystallization. We thus achieved new properties such as a higher melting point.’ He later focused on bonding catalysts to a polymer. ‘The industry uses these catalysts to accelerate chemical reactions, but they are expensive, so you want to re-use them. Bonding makes it easier to retrieve them.’

Alongside his research, Challa developed teaching programmes. He wrote an ‘Introduction to Polymer Chemistry’ to accompany his first course in 1966. This became a standard textbook way beyond Groningen, and an English translation was published too. The book is still in use, although it has since undergone numerous updates and now has co-authors. ‘I developed other courses too. It was nice to convey the knowledge that I acquired in my research in my teaching.’

Feringa

In the 1980s, the chemical industry hit a somewhat of a slump. Many businesses dialled down their research, and demand for polymer chemists dropped. Student numbers fell, although they did begin to increase later. Fifty years after its establishment, the Department of Polymer Chemistry – now with Professor Katja Loos at the helm – is still going strong.

Challa retired at the end of 1993, moving from Groningen to Heemstede and thus further away from the department. ‘But I still hear regularly from Groningen. I got to address Ben Feringa at the Royal Netherlands Academy of Arts and Sciences (KNAW) after he was awarded the Nobel Prize.’ Did he teach him? ‘I think so. Everyone attended our lectures in those days.’ Challa will be back in Groningen at the end of June, as one of the honorary guests at a symposium to mark the 50th anniversary of the department that he established. ‘I look back with much satisfaction and feel very grateful that I could start all this.’

In 1967, the University of Groningen was the first university in the Netherlands to host a department solely dedicated to polymer science. This will be celebrated on 30 June with a symposium.

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