On the mechanism of marine fouling-prevention performance of oil-containing silicone elastomers

Abstract

For many decades, silicone elastomers with oil incorporated have served as fouling-release coating for marine applications. In a comprehensive study involving a series of laboratory-based marine fouling assays and extensive global field studies of up to 2-year duration, we compare polydimethylsiloxane (PDMS) coatings of the same composition loaded with oil via two different methods. One method used a traditional, one-pot pre-cure oil addition approach (o-PDMS) and another method used a newer post-cure infusion approach (i-PDMS). The latter displays a substantial improvement in biofouling prevention performance that exceeds established commercial silicone-based fouling-release coating standards. We interpret the differences in performance between one-pot and infused PDMS by developing a mechanistic model based on the Flory–Rehner theory of swollen polymer networks. Using this model, we propose that the chemical potential of the incorporated oil is a key consideration for the design of future fouling-release coatings, as the improved performance is driven by the formation and stabilization of an anti-adhesion oil overlayer on the polymer surface.

Removal of Free Liquid Layer from Liquid-Infused Catheters Reduces Silicone Loss into the Environment while Maintaining Adhesion Resistance

“…Previous investigations of liquid-infused silicone have suggested that a thin, stable free liquid layer is critical to successful fouling resistance, as it acts as a physical barrier and reduces the force required to release attached fouling organisms. [14,39] To assess if removal of the free liquid layer in our system impacted the ability of foulants relevant to CAUTI to adhere to the surface, we incubated both LL and ØLL samples with the host protein fibrinogen and the bacterium E. faecalis . The results ( Figure 3) , showed that both LL and ØLL samples effectively resisted fibrinogen and E. faecalis adhesion, showing significantly less surface attachment compared to controls (Fibrinogen: P < 0.0001 and P = 0.0001, respectively; E. faecalis : P < 0.0001 and P = 0.009, respectively).…”

“…(2022) calculated that at a ∼20% loss of free liquid from a liquid-infused silicone bulk would result in a system in which a free liquid layer would no longer be able to re-form at the surface. [39] Our results suggest that for medical applications, silicone infused to ∼80% of its Q max value may contain just enough free liquid to create a dynamic interface that resists adhesion by proteins and microorganisms, while not enough to be easily lost into the environment.…”

“…[7] In addition, it is well understood that physical contact of a solid with a free liquid layer can also easily result in layer disruption and removal. [39] Given these facts, it is most likely that liquid-infused urinary catheters in vivo are being frequently subjected to conditions which can disrupt and/or remove any free liquid layer present on the catheter surface. Yet recent in vivo results demonstrate that infused catheters remain highly effective at resisting surface adhesion, despite the fact that they are unlikely to have a uniform liquid layer at the surface.…”

Silicone-Based Lubricant-Infused Slippery Coating Covalently Bound to Aluminum Substrates for Underwater Applications

“…While both coatings exhibited superior corrosion resistance, LISS prevented almost complete biofilm attachment of both aquatic species in short-term laboratory studies. In contrast to CL-PDMS, the presence of residual, unbound silicone oil in LISS enhances the anti-biofouling performance of PDMS by forming an additional stable liquid–liquid interface that separates the solid surface from the fouling liquid media . Despite the superior corrosion resistance, the CL-PDMS coating should be further investigated for its damage tolerance, while the self-healing properties imparted to CL-PDMS by the infusions of silicone oil could further improve the overall corrosion resistance.…”

Synergistic Benefits of Micro/Nanostructured Oil-Impregnated Surfaces in Reducing Fouling while Enhancing Heat Transfer

“…Here, we utilize non-toxic, pitcher-plant-inspired slippery liquid-infused porous surfaces (SLIPS) or liquid-infused surfaces (LIS) − to mitigate biofouling by reducing the settlement and adhesion of fouling organisms, − thereby maintaining good thermal exchange between hot and cold fluids in heat exchangers. Another notable advantage of such solid–liquid composite surfaces is hydrodynamic drag reduction, − which can be exploited in the design of heat exchanger tubes.…”