Designing scalable elastomeric anti-fouling coatings: Shear strain dissipation via interfacial cavitation

Abstract

HypothesisSoft elastomers are promising anti-fouling materials and this has been demonstrated for many small elastomer/foulant interfaces. Toughness should control the adhesive fracture of large interfaces, although this has never been shown for elastomers. We hypothesized that energy-dissipative processes like interfacial cavitation are largely responsible for the absence of toughness-mediated fracture for larger elastomer/foulant interfaces. ExperimentsRigid and transparent model foulants of various length were adhered to elastomers exhibiting three different moduli. The length of the foulant and the height above the interfacial plane of the applied force were systematically varied. A phase diagram was established for designing low-modulus, anti-fouling materials as a function of foulant thickness and length. FindingsA new regime of interfacial detachment was observed, where foulants remained partially attached to the surface and interfacial cavitation initiated from the edge of the detached region. Interfacial cracks were arrested before de-bonding the foulant and the majority of the applied energy was dissipated as cavitation bubbles. Our analysis showed that the use of elastomers as anti-fouling materials is limited for large scale applications. Foulant dimensions constrain the design of anti-fouling elastomeric coatings as an applied shear stress can only be exerted at a height above the interface that is less than the foulant thickness. Design rules are presented for the correct fabrication of elastomers to be used as anti-fouling coatings over large interfacial areas.