Fog-harvesting potential of lubricant-impregnated electrospun nanomats

Hydrophobic PVDF-HFP nanowebs were fabricated by a facile electrospinning method and proposed for harvesting fog from the atmosphere. A strong adhesive force between the surface and a water droplet has been observed, which resists the water being shed from the surface. The water droplets on the inhomogeneous nanomats showed high contact angle hysteresis. The impregnation of nanomats with lubricants (total quartz oil and Krytox 1506) decreased the contact angle hysteresis and hence improved the roll off of water droplets on the nanomat surface. It was found that water droplets of 5 μL size (diameter = 2.1 mm) and larger roll down on an oil-impregnated surface, held vertically, compared to 38 μL (diameter = 4.2 mm) on a plain nanoweb. The contact angle hysteresis decreased from ~95 to ~23° with the Krytox 1506 impregnation.