Natural product antifoulants: One perspective on the challenges related to coatings development

Fouling of surfaces by abiotic and biotic substances has molecular, microbial, and macro-organismal levels of organization. Fouling involves molecular bonding and biological adhesives. Existing commercial solutions to fouling are antifouling or foul-release. Antifouling uses broad-spectrum biocides which kill foulers by virtue of oxidation or toxic metal ions. Foul-release coatings are dimethyl silicone polymers that foul, but clean easily. The best foul-release coatings also contain additives that kill organisms. Environmentally unacceptable consequences of toxic antifouling coatings, especially those based on organotins, have prompted interest in antifoulants found in living organisms. Laboratories worldwide now use bioassays with target fouling organisms to direct purification and identification of antifoulant compounds. Natural antifoulants are common and include toxins, anesthetics, surface-active agents, attachment and/or metamorphosis inhibitors and repellents. Development of commercial coatings using natural products is blocked by cost, the time horizon to meet government regulations and performance standards based upon coatings with unacceptable environmental impacts. If blocks are removed, the potential for environmentally acceptable solutions that combine natural products with organic biocides is high.