No abstract

We demonstrate a facile way of cross-linking hydrophobic perfluoropolyethers, PFPEs, with a series of hydrophilic poly(ethylene glycol)s, PEGs, to prepare a range of amphiphilic networks for use as fouling-release coatings. The PFPE matrix of the networks endows the coating with a low surface energy while the PEG is added to weaken fouling adhesion. It is therefore envisioned that the coating surfaces of these optically transparent and mechanically robust films will display hydrophobicity leading to nonfouling and fouling release characteristics. Two kinds of functionalized PEG oligomers have been cross-linked with reactive, dimethacryloxy-functionalized PFPE oligomers to form a range of amphiphilic networks: (i) a monomethacryloxy-functionalized PEG macromonomer (454 g/mol) (PEG454-MA) which was used to yield blends with flexible PEG chains on the surface as well as in bulk and (ii) a dimethacryloxy-functionalized PEG (550 g/mol) (PEG550-DMA) which results in PEG chains that are relatively more restricted in the network blends and serve as an added difunctional cross-linker for the network along with the dimethacryloxy-functionalized PFPE. The PFPE/PEG cross-linked networks coated on a substrate show very low swelling characteristics in water when PEG454-MA comprises not more than 10 wt % of the overall composition or when PEG550-DMA is used and does not comprise more than 30 wt % of the overall composition. The PFPE/PEG454-MA coatings having PEG chains with one untethered chain end were found to display relatively high spore and barnacle release performance in comparison to PFPE/PEG550-DMA coatings which have the PEG chains in a more restricted network topology.

No abstract

Silicone coatings are currently the most effective non-toxic fouling release surfaces. Understanding the mechanisms that contribute to the performance of silicone coatings is necessary to further improve their design. The objective of this study was to examine the effect of coating thickness on basal plate morphology, growth, and critical removal stress of the barnacle Balanus amphitrite. Barnacles were grown on silicone coatings of three thicknesses (0.2, 0.5 and 2 mm). Atypical (''cupped'') basal plate morphology was observed on all surfaces, although there was no relationship between coating thickness and i) the proportion of individuals with the atypical morphology, or ii) the growth rate of individuals. Critical removal stress was inversely proportional to coating thickness. Furthermore, individuals with atypical basal plate morphology had a significantly lower critical removal stress than individuals with the typical (''flat'') morphology. The data demonstrate that coating thickness is a fundamental factor governing removal of barnacles from silicone coatings.