Mechanical Properties of Protective Coatings against Marine Fouling: A Review.

Alessandro Pistone,Annamaria Visco,Cristina Scolaro

doi:10.3390/polym13020173

Alessandro Pistone, Annamaria Visco + Show 1 more

Open Access

https://doi.org/10.3390/polym13020173

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Abstract

The accumulation of marine organisms on ship hulls, such as microorganisms, barnacles, and seaweeds, represents a global problem for maritime industries, with both economic and environmental costs. The use of biocide-containing paints poses a serious threat to marine ecosystems, affecting both target and non-target organisms driving science and technology towards non-biocidal solutions based on physico-chemical and materials properties of coatings. The review reports recent development of hydrophobic protective coatings in terms of mechanical properties, correlated with the wet ability features. The attention is focused mainly on coatings based on siloxane and epoxy resin due to the wide application fields of such systems in the marine industry. Polyurethane and other systems have been considered as well. These coatings for anti-fouling applications needs to be both long-term mechanically stable, perfectly adherent with the metallic/composite substrate, and capable to detach/destroy the fouling organism. Prospects should focus on developing even “greener” antifouling coatings solutions. These coatings should also be readily addressable to industrial scale-up for large-scale product distribution, possibly at a reasonable cost.

Highlights

Submerged boat marine structures are subject to the formation and accumulation of biofouling in its various forms over time
The average surface roughness (Ra) measurements indicated that the microroughness value gradually decreased up to 0.1% Ag nanofillers (0.16 μm), resulting in ultrasmooth and non-stick surface
Condensation reaction of polyacrylate with polysiloxane leads to a hydrophobic, 6H pencil hardness and 5B cross-cut adhesion copolymer where the presence of acrylic chain ensures strong adhesion to substrate while the side-chain Si–O bonds from polysiloxane enable the copolymer to hydrolytically degrade so providing a self-polishing character with water contact angle equal to 98◦

Summary

Introduction

Submerged boat marine structures are subject to the formation and accumulation of biofouling in its various forms over time. One of the most important criterion in the design of antifouling or fouling release coatings is surface chemistry. Film thickness (t) has been identified as an important factor in fouling release materials with adhesion strength decreasing with the increase of film thickness as a function of (t)−1/2 [14] Another important factor is surface roughness that is known to increase settlement and adhesion strength of biomolecules, including the proteinaceous adhesives used by many marine organisms [19]. All the above-mentioned properties, match well with polydimethylsiloxane (PDMS) and fluorinated materials, which are explored extensively as fouling release coatings [20]. For these reasons, the design of efficient fouling resistant coating is carried out taking in mind surface chemistry, mechanical properties, durability, and substrate attachment. Contact angle values have been considered as well to evaluate the hydrophobic/hydrophilic behavior of each coating

Silane-Based Coatings

Epoxy Based Coatings

Other Systems

Surface roughness

Findings

Conclusions and Future Perspectives