Manipulation of the Superhydrophobicity of Plasma-Etched Polymer Nanostructures

Abstract

The manipulation of droplet mobility on a nanotextured surface by oxygen plasma is demonstrated by modulating the modes of hydrophobic coatings and controlling the hierarchy of nanostructures. The spin-coating of polytetrafluoroethylene (PTFE) allows for heterogeneous hydrophobization of the high-aspect-ratio nanostructures and provides the nanostructured surface with “sticky hydrophobicity”, whereas the self-assembled monolayer coating of perfluorodecyltrichlorosilane (FDTS) results in homogeneous hydrophobization and “slippery superhydrophobicity”. While the high droplet adhesion (stickiness) on a nanostructured surface with the spin-coating of PTFE is maintained, the droplet contact angle is enhanced by creating hierarchical nanostructures via the combination of oxygen plasma etching with laser interference lithography to achieve “sticky superhydrophobicity”. Similarly, the droplet mobility on a slippery nanostructured surface with the self-assembled monolayer coating of FDTS is also enhanced by employing the hierarchical nanostructures to achieve “slippery superhydrophobicity” with modulated slipperiness.

Plasma Texturing of Polymers

“…These oxidized oligomers are repulsed by the untreated sub-layer chains because of their more hydrophilic character. The hydrophilic character can be prevented if such a surface is then plasma-fluorinated to getdepending on the plasma parameters-the true Cassie-Baxter surface (H2O = 157 ± 2 °, H = 1.6  0.6°, mean distance between two features ≈ 70 nm) or the sticky superhydrophobic surface (H2O = 156 ± 5°, H = 65  4°, mean distance between two features ≈ 145 nm) as also noticed in [20]. Similar etching plasma phases fed with CF4/O2 mixtures [7] allow to achieve superhydrophobic and slippery surfaces whose morphology and distribution are plasmadependent.…”

“…Thus, the achieved pattern in the case of polymers could also proceed via aggregation, rearrangement, chain reptation or functional groups turn over. These polymer chemistry phenomena are enhanced by the chemical affinity and, therefore reactive plasmas can also produce patterns on polymeric surfaces [1,3,20,[23][24][25][26][27]. Furthermore, whatever the plasma chemical composition (O2 or Ar), the same trend for the roughness and for the periodicity of the texture for a plasma-treated PDMS surface is observed [3].…”

Superhydrophobic Civil Engineering Materials: A Review from Recent Developments

“…The WCA of this surface reached 160 • and the SA is 6 • after modification by fluoride. Du et al created a nanotextured surface by oxygen plasma [33]. By modulating the modes of hydrophobic coatings and controlling the hierarchy of nanostructures, droplet mobility can be manipulated easily.…”

Fabrication of Hydrophilic Surface on Rigid Gas Permeable Contact Lenses to Enhance the Wettability Using Ultraviolet Laser System

“…Plasma surface treatment is commonly used to form hydrophobic and hydrophilic surfaces [18]. Du et al [19] coated the polytetrafluoroethylene (PTFE) on high–aspect ratio nanostructures and obtained hydrophobic surfaces. They employed the oxygen plasma etching and laser interference lithography to create hierarchical nanostructures, which resulted in superhydrophobic surfaces.…”