Geometric study of transparent superhydrophobic surfaces of molded and grid patterned polydimethylsiloxane (PDMS)

Fabrication of an Anisotropic Superhydrophobic Polymer Surface Using Compression Molding and Dip Coating

“…Coatings 2017, 7,194 9 of 12 from about a 3 cm height and bouncing of the water droplet on the 3°-tilted coated sample was observed without water droplet adhesion, as shown in Figure 12b (Video S3). Thus, the surfaces prepared by means of the method (compression molding and dip coating) discussed herein demonstrated simple sample preparation and good anisotropic superhydrophobic performances with a low SA.…”

“…Coatings 2017, 7,194 3 of 12 tilting speed of 1.6°/s for the SA. The surface morphology was observed using a confocal microscope (VK-X200 series, Keyence, Osaka, Japan) and a scanning electron microscope (SEM, JSM-7600F, JEOL, Tokyo, Japan).…”

“…Coatings 2017, 7,194 4 of 12 dip coating were compared using SEM, as shown in Figure 6. After dip coating, the agglomerated TiO2 nanoparticles were randomly distributed on the mold surface.…”

“…The lines or grooves have been fabricated by lithography, embossing, imprinting, laser machining, the formation of wrinkles via mechanical compressing, or other fabrication methods [13,[18][19][20][21][22][23][24][25][26][27][28]. For mass production of an anisotropic wetting surface, replication of patterns using a mold seems to be suitable, but many studies have used poly(methyl methacrylate) (PDMS), which has a relatively long curing time and limited reusability of the mold [13,[18][19][20][21], and molds with an uncontrollable surface roughness and side wall slope by laser machining and wrinkle formation, which does not show a clear pattern shape [7][8][9][10][11]13]. Additionally, the high surface energy ink pattern printing method can create various anisotropic superhydrophobic surfaces with low cost and large scale production especially 2D paper based applications [29].…”

“…Among them, lotus leaves are typical isotropic superhydrophobic surfaces which can clean dust on the leaves by easy rolling of water droplets along all directions. Many artificial isotropic superhydrophobic surfaces inspired by nature have been fabricated by making nano or microscale surface patterns and low surface energy material coatings using various different fabrication methods, such as lithography, templating, chemical deposition, laser surface texturing, and nanoparticle coating [4][5][6][7][8][9][10][11][12]. In nature, rice leaves and butterfly wings have special anisotropic wettability and the water droplet can be easily moved along a certain direction, such as the direction parallel to the leaf edge in rice leaves or the radial outward direction of the body's central axis in butterfly wings.…”