A self-assembled polytetrafluoroethylene (PTFE) nanostructure is deposited on microcrystalline diamond (MCD) films, by use of physical and chemical vapor deposition in a two-step process, to produce (fully) superhydrophobic surfaces: high water contact angle (static, 165±2 deg ), very low hysteresis (dynamic, ∼4 deg ), and associated sliding angle (1 deg 5 ′ ±15 ′ ), thus combining the diamond infrared transparency and self-cleaning properties. These are interpreted in light of Wenzel and Cassie-Baxter wetting models, associated with structural microscopy of nano-micro rough PTFE/MCD surfaces, and present a promising perspective for self-cleaning infrared optics applications.
Superhydrophobic surfaces were produced on glass with self-cleaning and wide-angle anti-reflection in the near-infrared
(1.0-2.1μm). These properties resulted from a combination of surface energy and nano/micro-structured topology based
on silica nanoparticles (NPs), index grading and interference. In a two-layer approach (glass/silica NPs/PTFE), a water
contact angle (WCA) of 169<sup>°</sup>±2<sup>°</sup>was attained with very low hysteresis (≤ 2<sup>°</sup>), as well as high transmittance (93-94% at normal incidence). In a three-layer approach (glass/silica NPs/silica aerogel/PTFE), surfaces were produced with WCA of 158<sup>°</sup>±2<sup>°</sup>, also very low hysteresis (< 5<sup>°</sup>), and significant antireflection. This allowed for a normal transmittance of 99.5% or higher, which decreased less than 2% at +20<sup>°</sup> incidence. These results show that pronounced wide-angle antireflection and self-cleaning properties can be simultaneously attained by proper glass coating. Present advantages and limitations for potential applications are discussed.