Fabrication of Superhydrophobic Surfaces from Femtosecond Laser Patterned Surfaces

Abstract

A femtosecond oscillator is employed to create periodic grid patterns in a commonly used polymer, poly (methyl methacrylate), PMMA. The wettability measured in terms of static water contact angle shows that the laser patterning causes an enhancement in water contact angle and the magnitude of change depends on the irradiation fluence during writing. A water droplet placed on a laser-patterned surface spreads anisotropically and exhibits different static water contact angle along different directions. Micro-Raman and Scanning Electron Microscope studies carried out on laser patterned and nonpatterned regions clearly confirm that the observed wettability change is due to physical (morphological) changes rather than chemical changes. More interestingly, the replica of the periodic laser patterned structures created on a soft polymer, polydimethylsiloxane (PDMS), via soft lithography technique exhibits superhydrophobic behaviour with a rolling-off nature for the water droplet. This is likely to find variety of applications in diverse fields ranging from passive defogging of windscreen to waterproof clothing to non-stick cookware.

Oil-Grafted Track-Assisted Directional Transport of Water Droplets and Submerged Air Bubbles on Solid Surfaces

“…Tailoring of the surface wettability properties via physical as well as chemical methods is a subject of intense research as it finds applications in diverse areas, ranging from superhydrophobic textiles to therapeutic delivery. − The majority of these surfaces are fabricated by biomimicking naturally occurring animals or plants. For example, the surface of lotus leaves is mimicked to achieve superhydrophobic surfaces whereas desert beetle and pitcher plant surfaces are imitated to obtain wettability contrast and slippery surfaces, respectively. − Advances in the fabrication of hierarchical micro and nanoscale structures facilitated the creation of surfaces with extreme wettability, ranging from superhydrophobic to superhydrophilic surfaces. − Inspired by the fog-basking nature of the desert beetle, research has been carried out to create a wettability contrast surface that can harvest water from fog and humidity.…”