Effects of crosslink density in zwitterionic hydrogel coatings on their antifouling performance and susceptibility to silt uptake

Abstract

Hydrogel coatings effectively reduce the attachment of proteins and organisms in laboratory assays, in particular when made from zwitterionic monomers. In field experiments with multiple species and non-living material, such coatings suffer from adsorption of particulate matter. In this study, the zwitterionic monomer 3-[N-(2-methacryloyloxyethyl)-N,N-dimethylammonio] propanesulfonate (SPE) was copolymerized with increasing amounts of the photo-crosslinker benzophenon-4-yloxyethyl methacrylate (BPEMA) to systematically alter the density of crosslinks between the polymer chains. The effect of increasing crosslink density on the antifouling (AF) performance of the coatings was investigated in laboratory assays and fields tests. In both cases, the AF performance was improved by increasing the crosslinker content. The coatings reduced protein, diatom, and barnacle accumulation, and showed better resistance to biomass accumulation. The findings underline that the marine AF performance of hydrogel coatings does not only depend on the specific chemical structure of the polymers, but also on their physico-chemical properties such as rigidity and swelling.

Keywords:

• QCM
• zwitterion
• crosslinking
• swellability
• Navicula perminuta
• Balanus improvisus

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors are grateful to Kathrin Geßner and Antje Lieske (Fraunhofer IAP) for support with SEC in HFIP. The work was funded by Deutsche Forschungsgemeinschaft (DFG), grants LA 611/14-1, LA 611/14-2, RO 2524/4-1 and RO 2524/4-2 and Office of Naval Research (ONR) N00014-16-12979 and N0014-20-12244 (AR), N00014-16-1-2988 (ASC) and N00014-16-1-3125 (ASC, NA and JAF), N00014-16-1-3123 (KH and GS).