Sediment challenge to promising ultra-low fouling hydrophilic surfaces in the marine environment

Abstract

Hydrophilic coatings exhibit ultra-low fouling properties in numerous laboratory experiments. In stark contrast, the antifouling effect of such coatings in vitro failed when performing field tests in the marine environment. The fouling release performance of nonionic and zwitterionic hydrophilic polymers was substantially reduced compared to the controlled laboratory environment. Microscopy and spectroscopy revealed that a large proportion of the accumulated material in field tests contains inorganic compounds and diatomaceous soil. Diatoms adhered to the accumulated material on the coating, but not to the pristine polymer. Simulating field tests in the laboratory using sediment samples collected from the test sites showed that incorporated sand and diatomaceous earth impairs the fouling release characteristics of the coatings. When exposed to marine sediment from multiple locations, particulate matter accumulated on these coatings and served as attachment points for diatom adhesion and enhanced fouling. Future developments of hydrophilic coatings should consider accumulated sediment and its potential impact on the antifouling performance.

Keywords:

• hydrogel
• field test
• fouling release
• marine biofouling
• sediment

Acknowledgments

Financial support from the Deutsche Forschungsgemeinschaft (DFG), grants LA 611/14-1 and RO 2524/4-1, and from the Office of Naval Research (ONR), grant N00014-16-12979 (awarded to RUB) and N00014-16-1-3123 (awarded to FIT) is gratefully acknowledged. The work was partially supported by the Fraunhofer High Performance Center for Functional lntegration in Materials and by the facility for ion radiation and radionuclides RUBION (Access to XPS) at Bochum.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

Financial support from the Deutsche Forschungsgemeinschaft (DFG), grants LA 611/14-1 and RO 2524/4-1, and from the Office of Naval Research (ONR), grant N00014-16-12979 (awarded to RUB) and N00014-16-1-3123 (awarded to FIT) is gratefully acknowledged. The work was partially supported by the Fraunhofer High Performance Center for Functional lntegration in Materials and by the facility for ion radiation and radionuclides RUBION (Access to XPS) at Bochum