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Sunday 15 October 2017

Evonik new coating to make ships invisible to microorganisms


Evonik Industries plans to make ship hulls invisible to microorganisms and so to protect them against biofilms, algae, and bivalves. Growths of this kind, referred to as biofouling, push up fuel consumption in shipping, and thus also CO2 emissions on the world’s oceans.
Evonik is working on a solution to the problem in the form of new eco-friendly coatings that counteracts biofouling. The coating tricks microorganisms into perceiving plain water in front of them, rather than the ship’s hull; as a result, they often make no effort to settle on the hull.
Biofouling has long been a problem for shipping companies the world over: Organisms settle on the ship’s walls, changing the smooth surfaces into a rough and ragged shell. This increases frictional resistance in the water so that biofouling slows down ships. These then need more energy to maintain their speed, which is bad news for both fuel costs and the environment. Marine transport accounts for about 90 percent of global freight forwarding.
To protect ship hulls against biofouling, Evonik’s scientists are exploiting a trick in the new coating: In it, they combine a water-repellent (hydrophobic) silicone with a water-loving (hydrophilic) polymer. This results in the formation of amphiphilic polymers, in which hydrophilic and hydrophobic domains alternate. The hydrophilic domains attract water to the ship’s hull. This builds a sort of water shell around the polymers, camouflaging the hull from the organisms. The alternation with water-repellent domains further confuses the organisms:
If the microorganisms do nevertheless try to settle on the hull, the second defense mechanism of the hydrophobic domain—its anti-adherent action—should come into play: The base material for the new solution against biofouling, the SILIKOPON EF silicone hybrid resin from Evonik’s portfolio, makes it difficult right from the start for the organisms to settle on the hull.

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