Effects of accelerated ageing conditions on the mechanism of chemically-active antifouling coatings

The accelerated ageing of chemically-active antifouling coatings was investigated by performing in vitro and in situ static/dynamic cycles. One of the main objectives of this study was to develop an ageing test able to predict long-term antifouling coating performances in less than one year with a mechanism which is representative to the natural ageing. One self-polishing copolymer (SPC)-based coating and one controlled depletion polymer (CDP)-based coating were selected because of their well-known distinct mechanisms of action. Five static artificial conditions were used in cycles and their influence on the ageing of two coatings was investigated. Comparison of two key parameters such as erosion of the coatings and formation of a leached layer or a depleted layer at the surface of the two coatings were investigated in accelerated and in situ tests. Results support the different mode of action of the two coatings. The static artificial conditions were shown to affect the residual antifouling efficiency differently. Deionized water buffered at pH = 8 with tris(hydroxymethyl)methylamine was the only static artificial condition that led to an acceleration of both the formation of a leached layer or a depleted layer at the surface of the two coatings and their erosion.