Robust Coatings with Amphiphilic Surfaces for Control of Biofouling
Abstract
Biofouling of submerged man-made structures is inevitable and continues to be a challenging issue to overcome. Especially for ocean-going vessels, biofouling has severe consequences for ship operation and maintenance. Biofouling creates significant drag, which leads to increased fuel consumption, air pollution, and maintenance expenses. Ship hulls have also been recognized as vectors for invasive species. Thus appropriately dealing with biofouling can solve the economic and ecological challenges that are presented. Coatings containing toxic chemicals are the main method of reducing biofouling, however, the release of these chemicals into the environment is problematic. Thus, non-toxic means to combat biofouling are needed. Silicone elastomer based fouling-release coatings have shown some promise and are commercialized, but they have many drawbacks including poor mechanical properties and being prone to slime fouling. To overcome these drawbacks, the concept of self-stratified siloxane-modified polyurethane coatings has been developed. In addition to having a low surface energy surface due to the stratification of the siloxane component, these coatings have good mechanical properties and good adhesion to marine primers. Due to the high diversity of fouling organisms in the marine environment, it has been challenging to design a non-toxic coating that has good fouling-release performance for a broad spectrum of organisms. The creation of surfaces having amphiphilic character has been shown to be a potential approach to solving this problem and this concept has been applied to the siloxanepolyurethane system as well. In this project, the focus will be to study the effect of amphiphilic additives on the fouling-release performance of siloxane-polyurethane coatings. Amphiphilic copolymers of poly(dimethylsiloxane) (PDMS) and hydrophilic blocks will be synthesized to yield surface modifying amphiphilic additives (SMAAs) and incorporated into the siloxanepolyurethane coatings system. The block lengths of the hydrophilic and hydrophobic components will be varied as well as the amount of the amphiphilic copolymer in the coating system. Several different chemistries for the hydrophilic block will be explored and compared. Coatings will be evaluated for their surface properties and then evaluated for their fouling release properties using laboratory biological assays involving marine bacteria, two marine algae and barnacles. The laboratory assays will also be used to select coatings for testing at field immersion test sites around the world. Coating durability will also be assessed in a grooming experiment. The expected outcome of the project will be to have an understanding of the effects of the molecular parameters of the SMAAs on the surface properties and the fouling release performance of the coatings. The information generated can aid in the designing of new types of marine coatings to address the issues of biofouling without the use of toxic biocides.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 11, 2020
- Source ID
- N000142012151
Entities
People
- Dean C Webster
Organizations
- North Dakota State University
- Office of Naval Research
- United States Navy