2024 AIChE Annual Meeting
Novel Fouling Release Coating Based-Dynamic Surface Instability
This research aims to develop environmentally friendly coatings for ship hulls that effectively deter biofouling by weakening any adhesion to the point where hydrodynamic forces from the ship's motion can easily dislodge them. The elastomer utilized contains hygroscopic inclusions that absorb moisture, causing it to swell upon contact [Figure 1]. When this elastomer is bonded to a rigid substrate and absorbs water, it undergoes surface instability. The wavelength of this instability increases proportionally with the thickness of the coating. Increasing the amount of hydrophilic inclusion enhances moisture absorption, leading to greater swelling and increased surface instability. The research involves varying the levels of hydrophilic inclusion in the coatings and observing their effects. It’s observed that higher hydrophilic content not only increases swelling but also alters the pattern of water absorption in the coatings. Below, is an image of the distinct pattern exhibited by one film with 40% hydrophilic inclusion as it absorbs water as a function of time [Figure 2]. This swelling in the film occurs due to differences in the chemical potential of water between the external source and the film. The process slows down as the osmolarity difference between internal and external environments decreases towards equilibrium. Furthermore, the research demonstrates that attaching a dome-shaped adherent to these coatings leverages the elastic force generated during surface instability to effectively dislodge it. This property makes these coatings promising for applications on ship hulls to prevent fouling accumulation during extended voyages. Figure 1. Schematic representation of a foulant in contact with a hygroscopic elastomer bonded to a rigid substrate (A), which swells by absorbing water from the surrounding and undergoes a morphological instability (B) thereby pushing the foulant out of the surface. Figure 2. A) An example of the surface morphology observed with 40% hydrophilic inclusion in the coating. B) Wavelengths of the different coatings with varying amounts of hydrophilic inclusion plotted vs time.
