Fouling release

Springer-Verlag, Berlin, Heidleberg, pp 141-170 Callow ME, Callow JA (1998) Enhanced adhesion and chemoattraction of zoospores of the fouling alga Enteromorpha to some foul-release silicone elastomers. Biofouling 13 157-172... 

Tributyltin self-polishing copolymer technology (TBT-SPC) Tin-free chemically-active paints and fouling release... 

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). 

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. 

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. 

Holm E.R., Schultz M.P., Haslbeck E.G., Talbott W.J., Field A.J. Evaluation of hydrodynamic drag on experimental fouling-release surfaces, using rotating disks. Biofouling 20(4-5) (2004) 219-226... 

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. and Holm, E.R., Antifouling and foul-release a primer, in Recent Advances in Marine Biotechnology, Vol. I. Endocrinology and Reproduction, Fingerman, M., Nagabhushanam, R., and Thompson, M.F., Eds., Oxford and IBH Publishing, New Delhi, India, 1997, 497. 

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. 

The copolymer with fluorine-containing segment made the resulting membrane exhibiting fouling release property. Besides, the presence of PMAA segments in the copolymer could also induce the pH-responsive property of the membrane prepared. 

Zhao, X., Su, Y, Chen, W., Reng, J., and Jiang, Z. 2011. pH-responsive and fouling-release properties of RES ultrafiltration membranes modified by multi-functional block-like copolymers. Journal of Membrane Science 382 222-230. 

A potential solution to prevent fouling is to develop fouling release membranes that do not resist the adhesion of foulants, but have an active layer with a low surface energy so that adhered foulants can be readily washed away by hydrodynamic mixing in the membrane module [21] provided the water flux and salt rejection of the resulting membrane are not compromised. 

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. 

Terlezzi, A., Conte, E., Zupo, V. and Mazzella, L., 2000. Biological succession on silicone fouling-release surfaces Long term exposure tests in the harbour of Ischia, Italy. Biofouling 15, 327-342. 

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. 

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... 

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. 

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