Polydimethylsiloxane Microdomains Formation at the Polythiourethane/Air Interface and Its Influence on Barnacle Release

Fouling-Resistant Behavior of Hydrophobic Surfaces Based on Poly(dimethylsiloxane) Modified by Green rGO@ZnO Nanocomposites

In line with global goals to solve marine biofouling challenges, this study proposes an approach to developing a green synthesis inspired by natural resources for fouling-resistant behavior. A hybrid antifouling/foul release (HAF) coating based on poly(dimethylsiloxane) containing a green synthesized nanocomposite was developed as an environmentally friendly strategy. The nanocomposites based on graphene oxide (GO) and using marine sources, leaves, and stems of mangroves (Avicennia marina), brown algae (Polycladia myrica), and zinc oxide were compared. The effectiveness of this strategy was checked first in the laboratory and then in natural seawater. The performance stability of the coatings after immersion in natural seawater was also evaluated. With the lowest antifouling (17.95 ± 0.7%) and the highest defouling (51.2 ± 0.9%), the best fouling-resistant performance was for the coatings containing graphene oxide reduced with A. marina stem/zinc oxide (PrGZS) and graphene oxide reduced with A. marina leaves/zinc oxide with 50% multiwall carbon nanotubes (PrGZHC50), respectively. Therefore, the HAF coatings can be considered as developed and eco-friendly HAF coatings for the maritime industry.

Research Progress on Low-Surface-Energy Antifouling Coatings for Ship Hulls: A Review

The adhesion of marine-fouling organisms to ships significantly increases the hull surface resistance and expedites hull material corrosion. This review delves into the marine biofouling mechanism on marine material surfaces, analyzing the fouling organism adhesion process on hull surfaces and common desorption methods. It highlights the crucial role played by surface energy in antifouling and drag reduction on hulls. The paper primarily concentrates on low-surface-energy antifouling coatings, such as organic silicon and organic fluorine, for ship hull antifouling and drag reduction. Furthermore, it explores the antifouling mechanisms of silicon-based and fluorine-based low-surface-energy antifouling coatings, elucidating their respective advantages and limitations in real-world applications. This review also investigates the antifouling effectiveness of bionic microstructures based on the self-cleaning abilities of natural organisms. It provides a thorough analysis of antifouling and drag reduction theories and preparation methods linked to marine organism surface microstructures, while also clarifying the relationship between microstructure surface antifouling and surface hydrophobicity. Furthermore, it reviews the impact of antibacterial agents, especially antibacterial peptides, on fouling organisms' adhesion to substrate surfaces and compares the differing effects of surface structure and substances on ship surface antifouling. The paper outlines the potential applications and future directions for low-surface-energy antifouling coating technology.

First Barnacle (Amphibalanus amphitrite) Adhesion Strength Data on the Self-Polishing Coatings Off the Aegean Sea

The aim of this work is to study the adhesion strength of Amphibalanus amphitrite in the İzmir Bay and compare the results with the pseudobarnacle adhesion test. Normally, adhesion tests are performed to evaluate the performance of the antifouling coatings, but the test results can also be used to predict biofouling cleaning process efficacy. The biofouling process is highly dependent on environmental conditions. For this reason, laboratory tests are required to perform the performance tests on self-polishing coatings in cases where living organisms cannot be reached. For this purpose, different self-polishing antifouling coatings have been formulated. Field tests for the coatings were carried out in the Aegean Sea for 10 weeks. After 10 weeks, barnacle and pseudobarnacle adhesion tests were conducted on coatings. When the results were compared, similarity was observed between the adhesion strength of barnacles and pseudobarnacles with 10 mm diameter on coating with the rosin/xylene/BaSO4 (40:40:20 w/w %). The adhesion strength of barnacles and pseudobarnacles on the coating 12 was found to be 0.46 and 0.45 MPa, respectively. In conclusion, the present study exhibits the first data related to the adhesion strength of A. amphitrite on rosin-based self-polishing coatings in the Aegean Sea. Moreover, based on field tests, a pseudobarnacle adhesion test methodology was developed to mimic barnacles and the correlation between barnacle and pseudobarnacle tests was examined.

Non-isocyanate Polyurethane Coating with High Hardness, Superior Flexibility, and Strong Substrate Adhesion

Flexible hard coatings with strong adhesion are critical requirements for several foldable devices and marine applications; however, only a few such coatings have been reported. Herein, we report a non-isocyanate polyurethane (NIPU) coating prepared by the epoxy-oligosiloxane nanocluster-amine curing reaction and cyclic carbonate-amine polyaddition, where the former provides the coating with ceramic-like hardness and polymer-like flexibility while the latter polymerization results in NIPU with strong substrate adhesion. The coating is transparent (>92% transmittance), hard (5-7 H), and flexible (2 mm bending diameter). It has strong adhesion to various substrates including aluminum alloy, titanium, steel, glass, ceramic, epoxy, and polyethylene terephthalate (2-8 MPa), which can be attributed to the high density of polar groups in NIPU. Moreover, we can facilely endow the coating with anti-icing, self-cleaning, and anti-smudge capabilities by incorporating amine-terminated low-surface-tension polydimethylsiloxane (PDMS) to replace a part of the amine curing agent. Particularly, the mechanical properties of NIPU coatings are only slightly affected by the introduction of low-content PDMS since it intends to enrich on the surface. The novel coating has promising future for use in fields of foldable devices and marine applications.