Fouling release coating

Anderson et al., 2003) eventually leading to larger drag resistances than chemically-active AF coatings (Holm et al., 2004 Schultz, 2004). Additionally, the AF properties of pure PDMS are rather poor after relatively short immersion times, so foul-release coatings must incorporate leaching additives which can act as potent non-specific biocides (Rittschof, 2001), the environmental side-effects of which have not been fully assessed yet. 

The following additional drawbacks are traditionally associated to foul-release coatings (Anderson et al., 2003 Yebra et al., 2004) ... 

In spite of these disadvantages, some of which appear to be already overcome (Anderson et al., 2003), many successful case-stories of the use of foul-release coatings are available on fast-moving vessels and propellers (Anderson et al., 2003). However, the existence of powerful broad-spectrum synthetic biocides with satisfactory degradation profiles in sea water (e.g. Sea-Nine 211, Zn- and Cu- pyrithiones Yebra et al., 2004) means that chemically-active antifouling coatings will probably dominate the bulk market of AF paints for seagoing vessels for many years to come (Yebra et al., 2004). 

Anderson, C., Atlar, M., Callow, M., Candries, M., Milne, A., Townsin, R.L. The development of foul-release coatings for seagoing vessels. Journal of Marine Design and Operations, December issue (2003), 11-23. 

Pieper R, Ekin A, Webster DC, Casse F, Callow JA, Callow M, E. (2007) A combinatorial approach to study the effect of acrylic polyol composition on the pProperties of crosslinked sUoxane-polyurethane fouling-release coatings. J Coatings Techn Res 4 453 61... 

Brady, R.F., Jr. and Singer, I.L., Mechanical factors favoring release from fouling release coatings, Biofouling, 15, 73, 2000. 

Rittschof, D., Clare, A.S., Gerhart, D.J., Bonaventura, J., Smith, C., and Hadfield, M., Rapid field assessment of antifouling and foul-release coatings, Biofouling, 6, 181, 1992. 

J. Jones-Meehan, J. Celia, J.A. Montemarano, G. Swain, D. Wiebe, A. Meyer, R.E. Baier. Advanced nontoxic fouling release coatings. NRL/PU/6110-99-399, July 27, 1999. 

Fig. 1. Release force of Pseudo Bamcles (Epoxy studs ) from reference surfaces versus measured surface energy. The epoxy coatings is a marine anticorrosion layer the phenyl silicone systems are typical of hard cookware coatings PDMS 1,2,3.4 are soft PDMS-based systems with different filler types and levels, typical of fouling release coatings the fluorosilicone is a trifluorpopylmethyl-dimethyl silicone elastomeric coating...

G. G. Bausch and J. S. Tonge, Silicone technology for marine fouling release coatings systems. Conference Proceeding of Silicone in Coatings /, Brussels, 1996, PRA International. 

In this paper, we report two methods to control oil depletion from silicone foul release coatings ablative networks and tethered incompatible oils. The synthesis of ablative and tethered diphenyldimethylsiloxane oils, the incorporation of such oils into the silicone room temperature vulcanized (RTV) network and the foul release properties of RTV coatings containing the ablative and tethered oils are discussed. The residence time of radiolabeled diphenyldimethylsiloxane oils in silicone RTV topcoats is also addressed. Synthesis of the radiolabeled diphenyldimethylsiloxane oil and incorporation of the radiolabeled oil into the silicone network are discussed. In addition, the environmental partitioning of the radiolabeled oils in both freshwater and marine systems is presented with the material balance. 

GE foul release coatings are comprised of a silicone topcoat and a silicone oil additive, typically at 10 or 20 weight percent. The silicone topcoat, RTVll (GE Silicones) is a room temperature condensation moisture cure system, which contains a silanol terminated polydimethylsiloxane (PDMS), CaCOj filler, tetraethoxy-orthosilicate (TEOS) crosslinker and dibutyltin dilaurate, a Sn(IV) catalyst. The chemistry of this system is shown below in Figure 1. 

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. 

Bausch, G. G. Tonge, J. S. Silicone Technology for Fouling Release Coating Systems, presented at the Waterborne, High-Solids, and Powder Coatings Symposium, February 14-16,1996, pp 340-353. 

Beigbeder, A., Degee, P., Conlan, S.L, Mutton, R.J., Clare, A.S., Pettitt, M.E., Callow, M.E., Callow, JA., and Dubois, P. (2008) Preparation and characterisation of silicone-based coatings filled with carbon nanotubes and natural sepiolite, and their application as marine fouling-release coatings. Biofoulir, 24, 291-302. 

R. C. Wallis and K. R. Strudwick, Nontoxic marine fouling release coatings. Surf. Coat. Aust. March 14-17 (1989). 

Nanoscale polymer strurtures are finding application in adhesives, luminescent displays, foul release coatings, and tissue engineering, to name a few examples where nanomechanics plays an important role. Reliahle methods to extract nanomechanical properties are needed and this chapter provides a numher of examples. We focus on recent results from our lahoratories. 

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