Reduction of ice adhesion on nanostructured and nanoscale slippery surfaces

Ice nucleation and accretion on structural surfaces are sources of major safety and operational concerns in many industries including aviation and renewable energy.Common methods for tackling these are active ones such as heating,ultrasound,and chemicals or passive ones such as surface coatings.In this study,we explored the ice adhesion properties of slippery coated substrates by measuring the shear forces required to remove a glaze ice block on the coated substrates.Among the studied nanostructured and nanoscale surfaces[i.e.,a superhydrophobic coating,a fluoropolymer coating,and a polydimethylsiloxane(PDMS)chain coating],the slippery omniphobic covalently attached liquid(SOCAL)surface with its flexible polymer brushes and liquid-like structure significantly reduced the ice adhesion on both glass and silicon surfaces.Further studies of the SOCAL coating on roughened substrates also demonstrated its low ice adhesion.The reduction in ice adhesion is attributed to the flexible nature of the brush-like structures of PDMS chains,allowing ice to detach easily.

Interfacial Strategies for Smart Slippery Surfaces

The problem of contact line pinning on surfaces is pervasive and contributes to problems from ring stains to ice formation.Here we provide a single conceptual framework for interfacial strategies encompassing five strategies for modifying the solid-liquid interface to remove pinning and increase droplet mobility.Three biomimetic strategies are included,(i)reducing the liquid-solid interfacial area inspired by the Lotus effect,(ii)converting the liquid-solid contact to a solid-solid contact by the formation of a liquid marble inspired by how galling aphids remove honeydew,and(iii)converting the liquid-solid interface to a liquid-lubricant contact by the use of a lubricant impregnated surface inspired by the Nepenthes Pitcher plant.Two further strategies are,(iv)converting the liquid-solid contact to a liquid-vapor contact by using the Leidenfrost effect,and(v)converting the contact to a liquid-liquid-like contact using slippery omniphobic covalent attachment of a liquid-like coating(SOCAL).Using these approaches,we explain how surfaces can be designed to have smart functionality whilst retaining the mobility of contact lines and droplets.Furthermore,we show how droplets can evaporate at constant contact angle,be positioned using a Cheerios effect,transported by boundary reconfiguration in an energy invariant manner,and drive the rotation of solid components in a Leidenfrost heat engine.Our conceptual framework enables the rationale design of surfaces which are slippery to liquids and is relevant to a diverse range of applications.