Sulfobetaine-based amphiphilic polymer coatings for antifouling and fouling release applications
Alexander Dundua, University Duisburg-Essen, Essen, GermanyKevin Daumann, University Duisburg-Essen, Essen, GermanyMathias Ulbricht, University Duisburg-Essen, Essen, Germany
Biofouling is a general problem for marine industry from both economical and ecological points of view. Surfaces subjected to aquatic environment are susceptible to attachment of marine microorganisms, which further represent a convenient platform for the growth of more complex aquatic species. Consequently, a whole set of problems arises, ranging from increased biocorrosion to increase in fuel costs due to higher surface roughness and increased drag of sea vessels. In recent years the demand for nonbiocidal antifouling coatings has been fueled by the ban on the application of once popular tributyl tin (TBT) based coating systems. Even though several other nonbiocidal alternatives have been developed, expected future restrictions on their application still provide a significant driving force for the development of nonbiocidal coating systems.[1,2]
Even though hydrophobic and hydrophilic coating systems have proven valid for antifouling applications, such uniform systems also suffer from some drawbacks. Different microorganisms show different affinities to either hydrophobic or hydrophilic surfaces, eventually creating the conditioning layer for more complex organisms. Consequently, the current trend in nonbiocidal antifouling coating development is the formation of amphiphilic surfaces with nanoscale hydrophobic/hydrophilic domains.
In this work, we present our recent development of amphiphilic coating systems, from the synthesis of polymeric building blocks toward coating preparation and characterization. Work is mainly focused on sulfobetaine (zwitterionic) materials due to their high hydrophilicity, zero net charge and ability to form a tightly bound hydration layer on the surface. Coatings are prepared via embedding polysulfobetaine as linear macromolecules or microparticles into epoxide resin matrices under varied preparation conditions, or via direct cross-linking of functionalized copolymers.
Surface characteristics of obtained coatings have been analyzed by contact angle and zeta potential measurements as well as atomic force and scanning electron microscopy techniques. Antifouling behavior of the coatings has been evaluated via investigation of protein adsorption and bacteria adhesion.
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