A TEAM of chemistry researchers at the University of Sydney Nano Institute has developed a “nanostructured” surface coating that has anti-fouling properties without toxic components.
The coating employs “nanowrinkles”, and is engineered at a scale of billionths of a metre 100,000 times smaller than the width of a human hair.
The researchers were inspired by the carnivorous Nepenthes pitcher plant, which traps a layer of water on the tiny structures around the rim of its opening, creating a slippery surface that causes insects to slip into its pitcher where they are digested.
The nanostructured surface developed by the group is slippery and stops the initial adhesion of bacteria, inhibiting the formation of a biofilm from which larger marine fouling organisms can grow.
In the lab, the slippery surfaces resisted almost all fouling from a common species of marine bacteria, while control Teflon samples without the lubricating layer were completely fouled.
Not satisfied with testing the surfaces under highly controlled lab conditions with only one type of bacteria, the team also tested the surfaces in the ocean, with the help of marine biologist Professor Ross Coleman.
Test surfaces were attached to swimming nets at Watsons Bay baths in Sydney Harbour for seven weeks.
In the much harsher marine environment, the slippery surfaces were still found to resist fouling efficiently.
Biofouling is a significant issue for shipping costing millions per year in maintenance and extra fuel usage due to increased drag on ship hulls.
Research team leader associate professor Chiara Neto said the team was keen to understand how these surfaces work and also push the boundaries of the application, especially for energy efficiency.
“Slippery coatings are expected to be drag-reducing, which means that objects, such as ships, could move through the water with much less energy required,” she said.