Verifications of the antifouling effect of the cross-linked PVA coating

The settlement of marine organisms on artificial surfaces cause a number of problems including increased fuel consumption of ship as a result of increased fluid resistance. To prevent biofouling on surfaces, tributyltin (TBT) compounds, the most effective biocide, had been used as an active ingredient in antifouling paints. However, TBT use in antifouling paints has been banned because it has toxic effects on marine organisms, and antifouling materials that are non-toxic and consume low amounts of energy have been demanded. Therefore, we focused on the relationship between the precise control of chemical surfaces and barnacle settlement towards the development of a non-toxic antifouling material. We found that few barnacles had settled on surfaces modified by a thiol compound having a terminal hydroxyl group in laboratory tests. In this paper, we verified the antifouling properties of the cross-linked PVA coating in both laboratory and field conditions. The results showed that the settlement rate increased with the amount of the cross-linking agent added, and the sample containing 10 wt％ of the cross-linking agent showed the lowest settlement rate in laboratory tests. Furthermore, the cross-linked PVA coating demonstrated antifouling activity for a period of at least 3 months under field conditions.