Coating that 'Twitches' helps keep ships free of fouling

11 Sep 2019

Engineers at Duke University in Durham, UK, have developed a polymer that keeps ships’ bottoms clean by “twitching like living skin”.

The paint-like coating – which is not toxic - combats hull fouling by preventing marine organisms from collecting on hulls by physically moving on the microscopic level and thus dislodging bacteria from the surface without toxic chemicals.

Marine life loves to colonise almost any solid surface if it gets half a chance and once a collection of seaweed, barnacles, molluscs, bivalves and worms sets up house they can turn even the sleekest of racing hulls into something about as hydrodynamic as a burst mattress. This can not only slow down the ship, but also reduce fuel efficiency as the vessel burns more fuel to drag along its unwelcome guests.

The Duke University approach to rid ships of fouling builds on earlier work of Duke engineer, Xuanhe Zhao, who has developed a way of causing polymers to deform when stimulated. This “twitching” can be either in waves and bumps or in specific patterns so the polymer can be programmed to twitch in a way that is most effective in dislodging bacteria before it can establish itself.

“We have developed a material that ‘wrinkles,’ or changes its surface in response to a stimulus, such as stretching or pressure or electricity,” says Zhao. “This deformation can effectively detach biofilms and other organisms that have accumulated on the surface.”

The team has tested the system in the laboratory using simulated seawater, biofilms and barnacles and they say that the polymer can be applied like a conventional paint. Aside from ships’ hulls they see the polymer having applications in removing biofilms from artificial joint implants and water purification membranes.