The performance of aminoalkyl/fluorocarbon/hydrocarbon-modified xerogel coatings against the marine alga Ectocarpus crouaniorum: relative roles of surface energy and charge

Abstract

The effect of a series of xerogel coatings modified with aminoalkyl/fluorocarbon/hydrocarbon groups on the adhesion of a new test species, the filamentous brown alga Ectocarpus crouaniorum, has been explored, and compared with the green alga Ulva linza. The results showed that E. crouaniorum adhered weakly to the less polar, low wettability coatings in the series, but stronger adhesion was shown on polar, higher surface energy coatings containing aminoalkyl groups. The results from a separate series of coatings tuned to have similar surface energies and polarities after immersion in artificial seawater (ASW), but widely different surface charges, demonstrated that surface charge was more important than surface energy and polarity in determining the adhesion strength of both E. crouaniorum and U. linza on xerogel coatings. No correlation was found between adhesion and contact angle hysteresis. X-ray photoelectron spectroscopy analysis of samples after immersion in ASW confirmed the presence of charged ammonium groups on the surface of the aminoalkylated coatings.

Keywords:

• marine biofouling
• xerogels
• brown algae
• Ectocarpus crouaniorum
• Ulva linza
• fouling-release
• surface energy
• charge

Acknowledgements

E. Evariste thanks International Paint Ltd for a Studentship supporting these studies. JAC/MEC and MRD thank the Office of Naval Research (awards N00014-08-1-0010 and N0014-09-1-0217 respectively) for partial support of these studies. CMG and MRD thank Jill Fornalik (SUNY Buffalo) for her assistance in acquiring AFM data for surface roughness and Young’s modulus.