'Botox for plastic' prevents polymer ageing

CSIRO has developed a material that prevents plastic from ageing and, when applied to plastic lining, can clean up exhaust gases from power plants much more effectively than existing methods.

Currently, the techniques industry use to separate out raw materials such as gases, liquids and solids are extremely energy intensive, accounting for 40% of the world’s energy use each year. Lead author Dr Sam Lau explained: “At the moment, power generators rely on plastic linings made up of tiny holes just one nanometre wide; a tiny fraction of a width of a human hair.

“For decades, scientists have been trying to improve the efficiency of this process by using plastics with larger holes. However, these larger openings tend to age very quickly and collapse within a matter of days.”

Writing in the journal Angewandte Chemie, the researchers stated: “While super glassy polymers are initially very porous, and ultra-permeable, they quickly pack into a denser phase becoming less porous and permeable.” As their gas permeability reduces, so too does their potential to be used as gas-separation membranes.

“What we’ve done is make use of incredible compact materials known as metallic organic frameworks - or MOFs - which have the surface area of a football field in just one gram,” said Dr Lau.

“We found that the density of the MOFs acts like a shot of botox and actually freezes the larger holey structures in place for an entire year.”

Dr Sam Lau holding up a plastic membrane that has received a ‘shot of botox’.

According to the researchers, this marks the first time that ageing in super glassy polymers has been “inhibited whilst maintaining enhanced CO₂ permeability for one year and improving CO₂/N₂ selectivity”.

It also makes lining with larger holes a viable option for industry, allowing for gas separation processes to be completed at 50 times the speed. Not only does this translate into huge cost and efficiency savings, said Dr Lau, but it is also a more environmentally friendly approach.

Dr Lau said the technique has the potential for cleaning up exhaust gases from power plants; enhancing the purity of natural gas streams; separating water from alcohol (a key process in biofuel synthesis); and dye removal in the textile industry.

“We’re extremely excited by this discovery and hope to see it being applied commercially within one to two years,” he said.

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