It will soon be possible to replace toxic antifouling paints used to avoid ships from being colonized by micro sea organisms. How? Scientists from Bremen's University are developping a coating directly inspired by palm tree seeds.
Fouling is composed by all kinds of sea organisms, both animal and vegetal, fixed on boat's hulls and immersed parts.
They add a load to the ship, and alter its hydrodynamic shape. Its performances are reduced and it becomes less fuel-efficient, more expansive, and less eco-friendly.
A worrying pollution.
Usually, Shipowners use to apply special paints on immersed parts, designed to diffuse away toxics substances. This biocidal substances reduce the fouling by killing all of the fixing organisms. Strongly controversial, they are however still massively used because of the lack of alternative solutions.
But in nature, living beings also need to fight against this fouling. That's what a german scientist team discovered by studying the seeds of more than 50 species of palm trees. After immersing them during 12 weeks in the North sea, they resulted being quite clean, and a dozen of them were even totally spotless. The fact is that this trees conquier new territories by scattering their seeds with sea streams. Seeds have more chances to resist the trip if they are not covered with other organisms.
So, as always, evolution, by selecting the most adapted, found an amazing, efficient and high tech solution: by having a close look to the micro structure of the surface of the cleanest seeds, especially for the species dypsis Rivularis, K. B. Mühlenbruch, doctor at the Biomimetism Innovation Center (BIC) of Bremen University, noticed that they were... Hairy! This superficial fibers, by the way they constantly move, prevent all kind of settlers to find a place were to fix them.
After the discovery, the invention.
Learning the lessons from this unique experience, the team focused on how to synthesize a material which has the same propreties. From a sillicon base, they designed a surface lined with fibers that should, as the seed's "skin", repel all the settlers. The idea is to create a innovating coating for boat's immersed parts, preventing, by its structure and not by its toxicity, any sea weeds or organisms from corrupting the ship.
Tests are still being carried out and the first results are very promising. But K. Mühlenbruch, cautious, still specifies that work have to be done since the product will be marketed.
From left to right: dypsis Rivularis' seeds; a seed's surface (electronic microscope) ; the new synthetic material (electronic microscope); a sample of this material after 12 weeks in the North Sea.© Biomimetics Innovation Centre (BIC), University of Applied Sciences