Plastic fantastic

By Chris Rodley

Photo of researchers

In 1998, a laboratory technician walked into the office of CSIRO chemist Ezio Rizzardo (PhD ’69) with a printout of the results from his latest experiment.

Up to that point, the researcher had spent almost 20 years investigating new ways of creating polymers, the building blocks of modern life used in everything from plastic cups and water filters to paint and motor oil. He had made steady progress in the field, but no revolutionary breakthroughs.

As Rizzardo and a colleague looked over the results – a graph from an instrument known as a gel permeation chromatograph – he saw that the polymer chains created by the experiment were much more uniform in size than those formed by conventional techniques. They had stumbled onto an entirely new way of making polymers.

“We knew straight away that something special and highly desirable had occurred,” Dr Rizzardo recalls. “I just said ‘wow!’”

The process he had discovered – known as reversible addition fragmentation transfer, or RAFT – is a form of free radical polymerisation, which creates polymers by adding a chain of free radicals together. RAFT is activated by a series of chemical reactions, all of which have fluctuating rates; only if these reactions have specific rates at the same time does polymerisation occur.

What remains so surprising about Dr Rizzardo’s results is that he had not planned to align the rates of the reactions: they coincided by chance. “It would have been very difficult to design such an experiment,” he says. “It was serendipity.”

Over the next few years, RAFT came to be regarded as a quantum leap forward because of the unprecedented control it gives over the properties of polymers. It has ushered in a new field of science, inspiring more than 10,000 journal articles and 500-plus patents for products ranging from drug capsules to eco-friendly paints.

I would make rocket fuel out of zinc dust and sulphur at high school

It also won Dr Rizzardo an invitation to join the Royal Society and to his being acclaimed earlier this year as one of the world’s top 20 chemists. The ranking, by international publishing company Thomson Reuters, was produced by comparing the citations of leading chemists to determine who made the greatest research impact over the past decade. Dr Rizzardo’s work had an average of 91 citations per paper.

Despite his passion for the field, chemistry was not the first career choice for the young Ezio. “I was born into a family of metal workers and was particularly interested in the internal combustion engine of cars,” he explains. “But when I went to my careers adviser and said I wanted to develop better motor engines, he said I couldn’t do that in Australia.”

Disappointed, he enrolled in medicine instead. In his second year, however, he attended his first, stomach-churning anatomy class “and that was enough to put me off”. Only then did he decide to become a chemist, enrolling in a Bachelor of Science at the University of New South Wales. Previously, he had enjoyed the subject – “I would make rocket fuel out of zinc dust and sulphur at high school” – but had not regarded it as a serious career choice.

He next enrolled in a PhD at Sydney University, studying the interaction of light with organic compounds, and then spent time in the US working on biologically active compounds such as vitamin D. Then, in 1976, he spotted a job vacancy at the CSIRO for an organic chemist to work in the emerging field of polymers. Despite knowing next to nothing about the materials, he applied for the job and got it.

As Dr Rizzardo learnt more about the process of creating polymers, he became frustrated at how much more complicated it was than making organic compounds such as vitamin D. “Compared to that, polymers are made from a whole range of different molecules, some short and some long, some branched and some straight,” he says. “For me, it was unsatisfactory. We knew if we could control the structure of the polymers better, we would control the properties better.”

A productive collaboration

Dr Rizzardo entered into a productive collaboration with chemical giant DuPont, which was interested in developing new polymers for car paint, and notched up a number of advances. Then came the career-defining discovery of RAFT, something that made “getting up early to get to the lab even more pleasurable”.

Since then, he has focused on further refining the process and has also begun to develop new applications for polymers, such as a plastic solar cell to replace expensive silicon cells.

While he acknowledges that serendipity shone on his RAFT experiment, he points to other factors that have been as important to his success. One is the support of talented colleagues; another, his decision to specialise in a narrow field rather than be a generalist.

Perhaps his most important skill, he adds, is his ability to filter out mediocre ideas and channel his energy into the most promising experiments.

“Researchers should ask whether colleagues will say ‘wow, that’s interesting’ if an experiment succeeds,” he says. “If the answer is no, then go back to the drawing board. It’s by rejecting bad ideas that you come up with the good ones.”