A LOW SURFACE FREE ENERGY APPROACH IN THE CONTROL OF MARINE BIOFOULING

A heavy growth of marine fouling organisms attached to shiphulls adversely affects operation of the ships, reduces their speed and increases their fuel consumption. At present toxic antifouling (AF) coatings are in use, but the recent concern about the environment makes it necessary to develop non-toxic AF systems. The author's approach is based on the surface free energies that govern adhesion. Measurements on liquid barnacle adhesive indicated that solids (coatings) with surface free energies lower than 12 dynes.cm(-1) are needed to prevent attachment. Adsorbed monolayers of perfluorinated surfactants have the lowest known surface free energies. These monolayers were simulated by mixing such compounds into an epoxy coating matrix and by synthesizing acrylate, methacrylate and siloxane (silicone) polymers with long perfluorinated sidechains. These polymers showed much lower surface free energies than Teflon type perfluorinated polymers with no sidechains, and some showed excellent AF characteristics.