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Biomimetic antifouling coatings are special coatings that prevent the accumulation of marine organisms on a surface. Typical antifouling coatings are not biomimetic but are based on synthetic chemical compounds that can have deleterious effects on the environment. Prime examples are tributyltin compounds, which are components in paints to prevent biofouling of ship hulls. Although highly effective at combatting the accumulation of barnacles and other problematic organisms, organotin-containing paints are damaging to many organisms and have been shown to interrupt marine food chains.〔Salta, M., Wharton, J. A., Stoodley, P., Dennington, S. P., Goodes, L. R., Werwinski, S., Mart, U., Wood, R. J. K., Stokes, K. R., "Designing biomimetic antifouling surfaces", Philos. Trans. R. Soc., A 2010, 368, 4729. 〕〔Mueller, W. E. G., Wang, X., Proksch, P., Perry, C. C., Osinga, R., Garderes, J., Schroeder, H. C., "Principles of Biofouling Protection in Marine Sponges: A Model for the Design of Novel Biomimetic and Bio-inspired Coatings in the Marine Environment?", Mar. Biotechnol. 2013, 15, 375.〕〔1. Gittens, J. E., Smith, T. J., Suleiman, R., Akid, R., "Current and emerging environmentally-friendly systems for fouling control in the marine environment", Biotechnol. Adv. 2013, 31, 1738.〕 ==Chemical methods== Most antifouling coatings are based upon chemical compounds that inhibit fouling. When incorporated into marine coatings, these biocides leech into the immediate surroundings and minimize fouling. The classic synthetic antifouling agent is TBT. Natural biocides typically show lower environmental impact but variable effectiveness. Natural biocides are found in a variety of sources, including (sponges, algae, corals, sea urchins, bacteria, and sea-squirts), and include toxins, anaesthetics, and growth/attachment/metamorphosis-inhibiting molecules. As a group, marine microalgae alone produce over 3600 secondary metabolites that play complex ecological roles including defense from predators, as well as antifouling protection, increasing scientific interest in the screening of marine natural products as natural biocides. Natural biocides are typically divided into two categories: terpenes (often containing unsaturated ligand groups and electronegative oxygen functional groups) and nonterpenes. Various tannins (nonterpene), naturally synthesized by a variety of plants, are effective biocides when combined with copper and zinc salts. The tannins are able to flocculate with a variety of cations, which then exhibit antiseptic properties. The most effective natural biocide is 3,4-dihydroxybufa-20,22 dienolide, or bufalin (a steroid of toad poison from ''Bufo vulgaris''), which is over 100 times more effective than TBT at preventing biofouling.〔 Bufalin is however expensive. A few natural compounds with simpler synthetic routes, such as nicotinamide or 2,5,6-tribromo-1-methylgramine (from ''Zoobotryon pellucidum''), have been incorporated into patented antifouling paints.〔 A significant drawback to biomimetic chemical agents is their modest service life. Since the natural biocides must leech out of the coating to be effective, the rate of leeching is a key parameter. Where La is the fraction of the biocide actually released (typically around 0.7), a is the weight fraction of the active ingredient in the biocide, DFT is the dry film thickness, Wa is the concentration of the natural biocide in the wet paint, SPG is the specific gravity of the wet paint, and SVR is the percentage of dry paint to wet paint by volume. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Biomimetic antifouling coating」の詳細全文を読む スポンサード リンク
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