Synthesis of ultrahydrophobic and thermally stable inorganic-organic nanocomposites for self-cleaning foul release coatings

- Low cost nanofiller of polydimethylsiloxane/SiO2-ZnO nanocomposites were synthesized.
- The nanofiller featured stable, well-dispersed, uniform particle morphology.
- Ultra-smooth surface, well-dispersion nanoparticles lead to potential nanocomposite fillers.
- Surface wettability, hydrophobicity, roughness and free energy are a key of self-cleaning FR.
- The nanofiller showed potential as FR self-cleaning via a physical repelling mechanism.

A conformal novel and low-cost series of elastomeric high-molecular weight polydimethylsiloxane (PDMS)/controlled SiO2-doped ZnO nanocomposites were accurately synthesized via hydrosilation curing. Different concentrations of doped nanospheres were inserted in the nanocomposite via in situ technique. The synergetic effect of micronanobinary scale roughness and controlled fouling on different kinds of substrates was determined. The hydrophobicity, roughness, and free-energy properties were investigated as self-cleaning and fouling release (FR) factors. The nanocomposites were also subjected to various tests on surface adhesion and mechanical properties, such as impact, T-bending, crosscut, and abrasion resistance. The anticorrosive features of nanocomposites were investigated through salt spray test. The mechanical tests and salt spray test exhibited the most profound effect by incorporation of 0.5% SiO2-doped ZnO nanospheres, indicating well distributed SiO2-doped ZnO nanofillers (0.5%). Results indicate that the nanocomposites retained the nanostructure characteristics under thermal and irradiation treatments. Furthermore, microfoulants of chosen bacterial progenies were applied on vinyl-ended PDMS/spherical SiO2-doped ZnO nanocomposites for about one month of laboratory assessments. These studies indicated the importance of good distribution of doped nanofillers on enhancing FR ability in the modeled nanocoatings. A particular increase in contact angle (CA, 167° ± 2) and the decrease in free energy of surface (9.24 mN/m) and microroughness indicated the FR functionality of these nanocomposites. Our findings show evidence that the developed nanocomposites demonstrated inert and nonwettable properties, superior physical characteristics, surface innerness and lotus effect, long-term durability under UV radiation, and thermal stability and resistance against a wide range of pH solutions, making them promising as efficient environment-friendly self-cleaning for coating of ship hulls.

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