Performance enhancement of natural antifouling compounds and their analogs through microencapsulation and controlled release

Abstract

Microencapsulation of natural antifouling compounds and their subsequent inclusion in polymeric coatings is a viable alternative to self‐polishing polymeric paint or rosin‐based ablative coatings. However, as naturally occurring compounds, the crude extracts of Octocorals (Renilla reniformis) or Pukalides, while found to be effective agents, are subject to both photolysis and chemical degradation in the marine environment. For these compounds to provide a viable alternative to persistent metallic toxicants such as organotins, they must be stabilized in the coating and released at their minimum effective dosages to provide for long term biofouling control. Enhanced activity of these biocides is reported, as demonstrated by their ability to repel the settlement of marine fouling organisms in short term testing at Beaufort, NC, Pearl Harbor and Coconut Island Hawaii. These assays, conducted over periods of 30 to 160 d, indicate that natural extracts are capable of repelling settlement to a greater degree when entrapped in cylindrical microstructures than when free associated into a polymeric film, or physically immobilized in a self‐polishing co‐polymeric paint.