Eco-friendly design of superhydrophobic nano-magnetite/silicone composites for marine foul-release paints

Advances in nanomaterials science are associated with developments fabrication methods in terms of energy saving, environment friendliness, and low cost. Self-cleaning nanocoatings with fouling release (FR) mechanism have been extensively investigated because of their non-stick, non-leachant, ecological, and economic advantages. Herein, we successfully modeled a series of self-cleaning technologies by using elastiometric siloxane polymer/nano-magnetite composites. The nanocomposite systems are dynamic non-stick surfaces and deter any fouling attachment through physical anti-adhesion. A series of superhydrophobic nanocomposites were synthesized through solution casting using different concentrations of nano-magnetite fillers. The fillers Exhibit 10-20 nun particle diameter range and spherical shape facet mainly with the {311} crystal lattice plane. The composites were dispersed in linear alpha,omega-dihydroxy polydimethylsiloxane (PDMS). Wettability characteristics, such as hydrophobicity, roughness, and free energy, were investigated by water contact angle analysis, field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy to evaluate self-cleaning and FR features. The nanocomposites were also subjected to various tests on surface adhesion and mechanical properties, such as tensile modulus, impact, T-bending, crosscut, and abrasion resistance. The anticorrosive features were investigated through salt spray test in 5 wt.% NaCl. Microfoulants of diatoms and bacterial progenies were selected and used to assess the anti-adhesion performance of the tailored nanosurfaces. The biological tests in laboratory was confirmed with a 3-month natural seawater field trial which indicated excellent inhibition of diatoms and bacterial growth and approved superior antifouling FR potential of the polymer/nano-magnetite (0.5%) composite hybrid coatings. This study provides insights into how structure-property relationship can enhance biological antiadhesion and FR performance. The uniform distribution of the nano-magnetite particles improved their water repellency, smoothness, and biological inertness. The particles also exhibited high static contact angle of about 153 degrees +/- 2 degrees and low surface free energy with the lotus effect. The bulk properties and durability as well as anticorrosive properties were improved. The PDMS/magnetite nano models possess numerous advantages, such as simplicity, non-toxicity, environmental sustainability, commercial feasibility, low fuel consumption, and desirable self-cleaning surfaces with durability characteristics.