Durable PDMS-based marine antifouling coatings
Biocides in marine coatings provide superior antifouling properties, but harmful effects on the eco system are inevitable. Environmentally friendly polydimethylsiloxane (PDMS) alternatives rely on biorepulsion, but inherently lack in durability due to their low E-Modulus making them unsuited for mechanical cleaning.
Scientists have now employed a commercially available 2K epoxy-amine system, which was modified with Bis(3-aminopropyl) terminated polydimethylsiloxane. This approach incorporates a robust 2K epoxy resin as a basis for reactive PDMS species combining the environmentally benign biorepulsion with mechanical stability. The immiscibility between epoxy and PDMS phases causes a spontaneous separation process thereby forming circular PDMS enriched surface domains as verified via EDX. A Key factor in improving the antifouling performance is to carefully tune the interstitial domain distances and ensure domain formation over the whole surface.
Coatings withstand even high-pressure cleaning
Since control over these parameters has proven to be challenging, the researchers introduced an amphiphilic polyglycol-PDMS compatibiliser (COMP) to the system specifically fit to balance out the internal interfacial tensions. Prepared coatings have shown to withstand even high-pressure cleaning with no sign of significant erosion. The use of 5.1 wt% COMP guarantees surface coverages up to 60%. Further domain control is gained by the variation of the time between application and cured state (pre-curing time). Specific topography and interstitial distance design were correlated to the coatings antifouling performance under real-life conditions in the North Sea (Norderney, Germany). Retardation of the biological growth is demonstrated to be present for 117 days after submersion until foulants settlement matches the control.
The study has been published in Progress in Organic Coatings, Volume 170, September 2022.
