Surface modifying amphiphilic additives and their effect on the fouling-release performance of siloxane-polyurethane coatings

Abstract

In this work, surface-modifying amphiphilic additives (SMAAs) were synthesized via hydrosilylation using various polymethylhydrosiloxanes (PMHS) and allyl-terminated polyethylene glycol monomethyl ethers (APEG) of varying molecular weights. The additives synthesized were incorporated into a hydrophobic, self-stratifying siloxane-polyurethane (SiPU) coating system to produce an amphiphilic surface. Contact angle experiments and atomic force microscopy (AFM), in a dry and hydrated state, were performed to assess changes in surface wettability and morphology. The antifouling and fouling-release (AF/FR) performances were evaluated by performing laboratory biological assays using the marine bacterium Cellulophaga lytica, the microalga Navicula incerta, the macroalga Ulva linza, the barnacle Amphibalanus amphitrite, and the marine mussel, Geukensia demissa. Several of the formulations showed improved AF/FR performance vs the base SiPU and performed better than some of the commercial standard marine coatings. Formulations containing SMAAs with a low grafting density of relatively high molecular weight PEG chains showed the best performance overall.

Keywords:

• Surface-modifying
• amphiphilic copolymers
• additives
• siloxane-polyurethane
• fouling-release coatings
• marine coatings

Acknowledgment

The authors would like to acknowledge the Office of Naval Research for financial support of this research under grant numbers N00014-16-1-3064, N00014-16-1-2988 and N00014-16-1-3125.

Disclosure statement

The authors declare no competing interest.

Data availability statement

The data that support the findings of this study are available from the corresponding author, upon reasonable request.

Supplemental material

Supplemental Material is available containing information on the synthesis of the SMAAs, data on the prepared coatings formulations both before and after water immersion, ¹H NMR and FT-IR for the synthesis of APEG 750 and SMAAs, the biological assay data from screening experiments involving C. lytica and N. incerta, as well as results from leachate toxicity assessments. More detailed tables used in the statistical analysis of biological assays can also be found here.