Heterocyclic Group Functionalized Siloxane-Based Polymers for Interruption of pH-Dependent Marine Settlement

Marine biofouling is the natural accumulation of organisms on substrates that reside in rivers, lakes, and seas. To combat this issue, polymer-based coatings historically utilized tin or copper compounds, which, though effective, are also highly toxic. In this study, a series of functionalized toxicant-free PDMS-type polymers were designed with pH buffer and zwitterionic moieties for fouling inhibition. The water contact angles ranged from 41 to 98°, demonstrating significant differences in the wettability of the coated surfaces. XPS and SEM-EDS testing confirmed the surface presence of buffer and zwitterionic functional groups. Assays were carried out using both laboratory and field testing against an array of marine species to gain an understanding of how these buffered polymer coatings hold up in the environment and to measure their antifouling and fouling-release capabilities. The organisms used for testing were a diatom, Navicula incerta, and two types of tubeworms, spirorbid and nonspirorbid serpulids. Piperazine and piperazine zwitterionic-based coatings performed the best overall as antifouling and fouling-release materials. Preliminary biological assays suggest that hydrophobic zwitterion-functionalized siloxane-based polymers may have both preventative antibacterial and antifouling interactions with target species compared to previously studied hydrophobic materials.