Functional Amphiphilic Siloxane-Based Surfaces: Controlling Marine Biofouling through Surface Chemistry

Abstract

Marine biofouling is the buildup of organic matter and organisms on surfaces in underwater environments. Despite battling this problem for thousands of years, there is still no perfect solution and biofouling still plagues naval operations and maritime industries today. Historically, the solutions have spanned everything from tar and pitch to copper siding. Today, the most effective coatings employ biocides, which leach out toxic additives and kill target organisms. While extremely effective, there are environmental concerns related to the effects of biocides on marine ecosystems, so alternative coatings are being explored. A considerable amount of research is now dedicated to the optimization and improvement of polymer-based technologies designed to prevent settlement and mitigate strong adhesion through the creation of inhospitable surfaces without the use of lethal additives. The work presented in this thesis represents further steps towards the development of more environmentally conscious materials, using a polymer-based coating to prevent both settlement and adhesion using surface chemistry. A previously established system designed specifically for implementation in marine coatings was used, composed of a polystyrene-b-poly(dimethylsiloxane-r-vinylmethylsiloxane) (PS-PDMS) block copolymers. Pendent vinyl groups along the PDMS block facilitate simple functionalization of the backbone, which in turn can be used for the modulation of surface chemistry. Through this system, novel structures were investigated for their success in marine antifouling and fouling release applications. Chapters 2 and 3 explore the incorporation of the stable radical nitroxide, 2,2,6,6-tetramethylpipiderin-1-oxyl (TEMPO) as an active inhibitor to the formation of strong interfacial bonds between marine adhesive cements and surfaces. Chapter 4 investigates the utility of morpholine as a hydrophilic group to imbue amphiphilicity to the PS-PDMS backbone. Lastly, chapter 5 briefly explores the morphology of the PS-PDMS block copolymer and its implications in coating performance.