Foul release performance

The incorporation of ablative and tethered oils into the silicone topcoat of fouling release coatings is a desirable mechanism for slow, controlled release of the silicone oil from the RTV topcoat. Once incorporated into the silicone network, the hydrolytically unstable Si-O-C bond in the ablative oil (Figure 3) should slowly degrade in water. Conversely, the tethered oil is chemically bonded into the silicone network and one end (the non-miscible portion) should phase separate to the surface of the PDMS. Both ablative and tethered oils contain diphenyldimethylsiloxane functionality, based on previous studies of the free oil. The approach was to synthesize both ablative and tethered diphenyldimethylsiloxane copolymers, incorporate the copolymers into the RTV topcoat and then measure the foul release performance of the coatings. Both oils are shown below in Figure 3. 

Foul Release Performance of Ablative and Tethered Oils... 

From the foul release results of the ablative and tethered oils, we can conclude that free oil is necessary in the silicone coating for optimal foul release performance. In... 

Antifouling performance testing is a very important and specific method for these types of paints. For several years, Hempel A/S has conducted both static and dynamic tests in the evaluation and optimisation of biocide-based AF paints and fouling-release paint products. 

In general, it may be concluded that despite the endeavor described earlier to develop low-fouling membranes via surface modification with nanoparticles, further research is still needed to investigate the combined effects of the water chanistry, the nature of the nanoparticles, and the coating conditions on the modified-manbrane performance and fouling mitigation. Also, careful control and monitoring of the nanoparticles released from the modified membranes are necessary to minimize potential environment (eco) toxicity effects (Tiede et al. 2009). 

Siloxane performed better than fluorocompoimd as an external release agent. Mold fouling occurred after 150 cycles (compared with 10 cycles for fluorocom-pound). The best performance (more than 600 cycles without maintenance) was obtained with permanent teflon coatings. 

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