Laboratoire MAPIEM (UR 4323)

Abstract

Any surface immersed in seawater is rapidly colonized by marine fouling (bacteria, algae, mollusks). This colonization has serious impacts, especially for the marine industry, such as biocorrosion, increased hydrodynamic drag and therefore fuel consumption, and transport of invasive species.
Antifouling coatings can be used to prevent immersed surfaces from fouling colonization. There are currently on the market two types of coatings:

• The Self-Polishing Coatings (SPC) which are erodible coatings based on hydrolyzable polymeric binders. Their antifouling efficacy relies on the release of biocides into the marine environment. They are very effective but toxic to the marine environment.
• The Fouling Release Coatings (FRC), which are hydrophobic coatings based on silicone elastomers without biocide. Their antifouling efficacy relies on limiting the strength of adhesion of fouling organisms, giving them self-cleaning properties. However, they are not effective at low speeds and during idle periods, and they remain covered with a biofilm even at high speeds.

The solution considered in this PhD thesis is an antifouling coating based on hydrolyzable silicone elastomers. This coating is a hybrid system between FRC and SPC since it combines:

• The low surface energy and the low elastic modulus of silicone elastomers (FRC) to limit the strength of adhesion of marine fouling and cause their detachment during navigation.
• The erosion properties of SPC which will result in a renewing of the surface, leading to the detachment of fouling during static periods and at low speeds.
• Moreover, like the FRC coatings, drag-reducing properties and thus fuel economy can be expected for this type of coatings.