Drop friction on liquid-infused surfaces

Trapping a thin liquid film in the roughness of a textured material creates a surface that is partially solid and partially liquid, referred to as a lubricant-impregnated surface. Those surfaces have recently raised a great interest for their promising industrial applications. Indeed, they proved to drastically reduce adhesion of a broad range of liquids, leading to enhanced mobility, and strong anti-biofouling, anti-icing and anti-fogging properties. In our talk we discuss the nature of the friction generated as a drop glides on a textured material infused by another liquid. Different regimes are observed, depending on the viscosities of both liquids. While a viscous drop is simply opposed by a Stokes-type friction, the force opposing a drop moving on a viscous substrate becomes non-linear in velocity. A liquid on an infused material is surrounded by a meniscus, and this specific feature is proposed to be responsible for the special observed frictions, on both adhesive and nonadhesive substrates.