Transparency and superhydrophobicity of cone-shaped micropillar array textured polydimethylsiloxane

Abstract

Transparent superhydrophobic surfaces have great potential for application to self-cleaning transparent windows. We suggest a fabrication method that combines laser beam machining and polymer casting. A UV nanosecond pulsed laser was used to machine arrays of holes into molds composed of 6061 aluminum alloy. Then, polydimethylsiloxane was cast into the laser-machined molds.To study the effects of the array geometry on superhydrophobicity and transparency, a series of micropillar arrays with different step sizes were fabricated. As a result, the critical step size at which the surfaces changed from hydrophobic to superhydrophobic was found to be approximately 80 µm. Cone-shaped micropillar arrays with 80 µm step size showed 175° maximum water droplet contact angle and were highly transparent throughout the 300-1000 nm spectral region. Sliding angle was observed to confirm the surfaces' self-cleaning ability. This work opens up the possibility of mass production of superhydrophobic, transparent, self-cleaning surfaces.

Laser engineering of biomimetic surfaces

“…The main advantage of the replication process is the fast production of large quantities, since mold substrates can be used multiple times compared to laser processing of individual samples. For mass production, the replication process is advised by the majority of the scientific community [393][394][395][396][397][398].…”

Preparation of Hydrophobic Surface on PLA and ABS by Fused Deposition Modeling

“…Polylactic acid (PLA) is widely used in agriculture, forestry, medical, and food industries, as well as packaging and other fields. Unique functions such as cleaning, anti-icing, anti-corrosion, water-reducing oil separation, liquid transport, and water collection [ 1 , 2 , 3 , 4 , 5 , 6 ] are needed in these fields. In daily life, the surfaces of automobiles, home appliances, and packaging with anti-fouling properties, as well as kitchen appliances with anti-fouling properties, are expected.…”

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

“…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.…”

“…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].…”