Release of Polymeric Biocides from Synthetic Matrices for Marine Biofouling Applications

Marine biofouling is a natural phenomenon representing one of the greatest problems in marine technology (navigation, aquaculture nets, etc). To circumvent these problems, antifouling paints or coatings, i.e. matrices containing biocidal species, are used to protect the submerged surfaces and objects. Polymers containing quaternary phosphonium or quaternary ammonium groups are promising biocidal materials. Such a biocidal polymeric material is the polymeric salt PSSAmC16 formed between the polystyrene sulfonate anion and the cetyltrimethylammonium cation. When embedded into a paint or a polymeric matrix, the cation of PSSAmC16 is gradually dissolved in the surrounding water through an ion exchange mechanism, offering the biocidal protection of the surface. In the present work, the release of PSSAmC16 from the synthetic polymeric matrix poly(methyl methacrylate), PMMA, was evaluated, as a function of the contact time with the surrounding aqueous environment. The PSSAmC16 content in the matrix varied from 0 up to 40% (wt/wt), while aqueous NaCl solutions with a salt concentration up to 2 M were investigated. The release of the polymeric biocidal was quantified through Total Organic Carbon (TOC) and Total Nitrogen (TN) measurements. Both methods reveal that the major part of the polymeric biocidal is released within a few days, while release increases with the PSSAmC16 content and it is enhanced by the salinity.