Nontoxic hull coating resists barnacles, may save ship owner...( North Carolina State University engi...)

North Carolina State University engineers have created a non-toxic "wrinkled" coating for use on ship hulls that resisted buildup of troublesome barnacles during 18 months of seawater tests, a finding that could ultimately save boat owners millions of dollars in cleaning and fuel costs.

The research conducted by Dr. Kirill Efimenko, research assistant professor in the Department of Chemical and Biomolecular Engineering, and Dr. Jan Genzer, professor in the same department, shows for the first time that surface coatings containing nests of different-sized "wrinkles" are effective in preventing barnacles from firmly latching on to the coatings.

"The results are very promising," Efimenko said. "We are dealing with a very complex phenomenon. Living organisms are very adaptable to the environment, so we need to find their weakness. And this hierarchical wrinkled topography seems to do the trick."

Researchers created the coatings by stretching a rubber sheet, applying an ultra-violet ozone treatment to it, and then relieving the tension, causing five generations of "wrinkles" to form concurrently. The coatings were further covered with an ultra-thin layer of semifluorinated material. During ocean tests performed in Wilmington, N.C., the wrinkled materials remained free of barnacles after 18 months of seawater exposure, while flat coatings with the same chemical composition showed barnacle buildup after just one month in seawater.

Engineers and scientists have strived for decades to uncover ways to keep barnacles off ship hulls. Barnacle colonization on a ship bottom increases the ship's "drag" in the water, forcing the engine to burn more fuel to maintain the same speed. After six months in the water, a ship's fuel consumption increases substantially, Efimenko said. That costs ship owners including the military plenty of extra cash.

"It's like running your air conditioner with the windows open," Genzer said.