16 Mar 2017

Catalyst - from corn to plastic

From Our Changing World, 9:06 pm on 16 March 2017

Chemist Sally Brooker, from the University of Otago and the MacDiarmid Institute, is developing a catalyst that could be used to produce degradable bioplastic from corn.


Work in progress in Sally Brooker's chemistry lab. Photo: RNZ / Alison Ballance

Sally describes herself as a co-ordination chemist, who designs new molecules, and then makes and tests them.

“What we do is put metals with ‘organic fluff’. And the structure of the ‘organic fluff’ is really important to the function of the metal.”

Sally’s metal of choice for this new catalyst is zinc. She describes the process of synthesizing a new molecule as being akin to cooking.

“You build up the fluff in a number of steps to get the structure and the shape that you need,” she says. “It’s like testing a cake. And just like in cooking you can burn it, you can have things that just don’t work.”

Sally Brooker and Hannah Davidson

Sally Brooker and Hannah Davidson in front of one of Hannah's experiments. Photo: RNZ / Alison Ballance

Sally usually works in developing switchable molecules that would work in nano-memory and could be used to make tiny computers. Developing catalysts is a new area for her, but she believes we need to seriously think about developing alternatives to oil-based plastics.

The catalyst that PhD student Hannah Davidson is working on would help turn lactides, from corn, into biodegradable plastic.

“We make a polymer from the lactide, which is just like putting lots of little lego building blocks into a great big chain, and that’s your plastic,” says Sally.

Hannah says it’s tricky to make the process as efficient as current petro-chemical processes, “so the key is to make it cheap, efficient and industrially viable.”

In 2015 Professor Brooker was awarded the University of Otago’s Distinguished Research Medal.

Lab book

Chemists keep lab books that describe every experiment they carry out. This experiment in one lab book is number 1286. Photo: RNZ / Alison Ballance

Hannah Davidson won the MacDiarmid Institute's Emerging Scientist Association (MESA) 3-minute research video competition in 2016, using claymation to explain her work developing a new type of catalyst.


One of Hannah's experiments in progress. The process is a little like inventing and then perfecting a recipe. Photo: RNZ / Alison Ballance