Biofouling control by superhydrophobic surfaces in shallow euphotic seawater

Potentiodynamic study of Al–Mg alloy with superhydrophobic coating in photobiologically active/not active natural seawater

“…The CA time evolution (see Fig.7a), indicates that in the +PAR+b mesocosm degrading phenomena are accelerated until superhydrophobicity is apparently lost after 3 weeks. These results agree with our previous work [20]. Clarifying aspects are suggested by the findings on the 5 th day, when on 'e' samples part of the SH surface presented CA>150°, no attached diatoms and intact structure, and remaining parts presented CA<150°, attached diatoms and relatively more altered structure.…”

“…Surfaces were ground with 320 to 4000-grit SiC paper, washed with ethanol and rinsed with deionized water before immersion. The superhydrophobic coating was prepared with commercially available fluoropolymer blend and fumed silica nanoparticles as described in [20]. The coating was applied on Al alloy samples at a distance of 5 cm and at a pressure of 3 bars by spraying directly onto the metal surface without any other preparatory or underlying primer coating.…”

“…Details concerning the location of the experiments and seawater mesocosms are described in [20]. We recall the 'PARb' nomenclature referring to the presence '+' or absence '-' of the photosynthetic active radiation (PAR) as provided by sunlight illumination and photobiology (b) in the two seawater mesocosms.…”

“…Even before mechanical damage, this can depend on critical water pressures inducing Cassie to Wenzel wetting transitions, in relation to partial/combined effects of hydrostatic loads [19]. This work is a continuation of investigations dealing with the behavior of a superhydrophobic treatment tested in a shallow euphotic zone vs. dark seawater sprayed on non-metallic substrates [20] Here, we evaluated with a potentiodynamic scan technique the behavior of aluminum with/without the same superhydrophobic coating tested in [20], evidencing the evolution of electrochemical parameters and surface wettability. Two seawater mesocosms were used: the first, exposed to the natural photoperiod (undergoing photobiological activity), the second, exposed in the dark (where photobiological activity is inhibited).…”

Explaining Evaporation-Triggered Wetting Transition Using Local Force Balance Model and Contact Line-Fraction

“…The latter displaying larger contact angle hysteresis due to the pinning of the three phase contact line (TPCL) 18 . For many applications, like self-cleaning 19 , anti-icing 20–24 , biofouling control 25 , drag reduction 26 , delaying frost growth 27 and tunable drug delivery 28 , maintaining the stable superhydrophobic Cassie-Baxter state is of primary importance, as these properties are lost when the droplet transits to the Wenzel state. Many studies have focused on stabilizing the wettability of the superhydrophobic surfaces and on the wetting-transition mechanism, through experimentation 29–32 , numerical simulation, and theoretical analysis 33 .…”