Fluorinated Ship-Hull Coatings for Non-Polluting Fouling Control

PACIFIC NW POLLUTION PREVENTION RESOURCE CENTER
POLLUTION PREVENTION RESEARCH PROJECTS DATABASE

Project Title: Fluorinated Ship-Hull Coatings for Non-Polluting Fouling Control

Date Last Updated: 11/96

Project Summary: Protection of ship-hulls from marine fouling organisms is essential for efficient fleet operation and energy conservation. To achieve this, ship hulls have been coated with antifouling paints that contain toxic material, such as copper and organotin, and create an environmental hazard due to continuous release of toxic materials. A cruiser size ship (35,000 sq. ft. hull area) releases approximately 2 lb. copper/day that may bring approximately 5 million gallons of sea water to toxic copper concentrations. Dozens of ships painted with conventional toxic antifouling paints can make a significant environmental impact in an enclosed harbor.

The objective of this project is to develop a nontoxic, zero discharge coating that protects ship hulls from marine fouling organisms. Unlike conventional antifouling paints, such coatings will not contain toxic materials, rather they will be designed to resist fouling or allow only weak adhesion of fouling organisms. Marine organisms use biopolymeric adhesive secretions for attachment. Theoretically, hull coatings with sufficiently low surface energy should prevent fouling because organisms would not be able to adhere to the hull surface.

In order to minimize adhesion, materials will be designed with the lowest possible surface free energy. The technical objectives are to: 1) simulate adsorbed fluorinated monolayers of closely packed perfluorinated compounds either by grafting perfluoroalkyl molecules to surfaces, by embedding perfluoroalkyl compounds into the surface of polymeric matrices, and by binding the perfluorinated compounds into a polymeric backbone to create comb type polymers with perfluoroalkyl sidechains, 2) determine the minimum amount of perfluorinated additive needed for optimum performance, 3) verify the effectiveness of these materials against the adhesion of marine fouling organisms.

The experimental coatings will be exposed to the marine environment to determine fouling resistance, fouling release, durability, and possible surface molecular changes caused by sea-water, biofilm, and fouling organisms. Low-surface energy easy-release coatings have been prepared. It has been found that the low-surface energy, although a major factor, is not the only determining factor in developing easy-release coatings. Other properties such as surface morphology, coating flexibility and thickness are important. The researchers are pursuing optimization of such coating properties and are attempting to correlate their contributions to easy-release performance.

Project Keywords: antifouling paints, coatings, minimally adhesive surfaces, ship hulls, perfluoroalkyl, fluorinated polyurethane, oxetane, nanoscale surface mapping

Organizing Performing Research: US Navy -- Naval Command, Control and Ocean Surveillance Center, and Naval Research Laboratory

Primary research Contact:
Mike Putnam
NCCOSC/RDT&E Division Code 521
53475 Strothe Rd.
San Diego, CA 92152-6325
PHONE: (619) 553-2926
FAX: (619) 553-2775
E-MAIL: putnam@nosc.mil

Date research Started/Completed: 3/94 - 9/97

Publications Based on Research:

Approximate Project Budget: $3,640,000

Primary Project Funder: Strategic Environmental Research & Development Project (SERDP)

Funder Contact:
Dr. Robert Holst
Program Manager for Compliance and Pollution Prevention
SERDP Program Office
901 North Stuart Street, Suite 303
Arlington, VA 22203
phone: (703) 696-2125
fax: (703) 696-2114
e-mail: holstrw@acq.osd.mil