Development of friendly antifouling coatings from marine algae

After the ban of TBT-based products, marine paint companies are urged to find an appropriate substitute to prevent biofouling on ship hulls. Biocides commonly used in antifouling paints to replace TBT have caused many doubts about their environmental effects. An alternative is offered by the development of antifouling coatings in which the active ingredients are compounds naturally occurring in marine organisms. Many recent studies confirm a potential for novel active ingredients in antifouling preparations from crude extracts of marine algae. We have shown in our studies that the extracts from Ceramium botryocarpum have an interesting antimicrofouling activity, in comparison with commonly used biocides. In situ tests have been conducted during July and August 2004 in the harbour of Lorient, and the first results of crude extracts incorporated in coatings are promising. The chemical characterization of the extracts is in progress. Further work is now needed to examine the precise role of such antifouling activity in nature, and to determine the specific antimicrobial activity against marine bacteria implicated in biofilms

Study of erodable paint properties involved in antifouling activity

To produce ecological marine paints, it is necessary to understand the phenomena involved in antifouling activity. Due to the multivariable components which have to be taken into account and due to their analytical intricacy, only studies based on selected properties are conceivable. In this study, four properties have been chosen, viz. erosion, biocide release, roughness and the physicochemical characteristics of the film surface. A principal-component analysis (PCA) of the experimental data has shown that, among the selected properties, only erosion affected antifouling efficiency. A more detailed investigation of erosion by quantifying global hydration and hydrolysis of immersed paints revealed the difficulty in linking the chemical structure of binders to the final erosion properties. Biocide release from paints, quantified by chromatographic methods coupled with UV detection, was inferior to the doses stated by the paint producers. These observations allowed the conceiving of formulations with reduced amounts of active molecules. The development of erodable, biodegradable binders associated with non toxic compounds is a promising way to obtain efficient antifouling paints compatible with existing, preventive systems