An Effect of Silicon Micro-/Nano-Patterning Arrays on Superhydrophobic Surface

Abstract

Superhydrophobic surface can be fabricated by creating a rough surface at very fine scale and modify it with low-surface energy material. To obtain the optimum superhydrophobicity, the surface roughness must be maximized. To avoid the limitation of scaling down the pattern size by using an expensive lithography tools, the surface roughness factor (r) was increased by means of changing an asperity shape so as to increase its overall surface area. In this paper, the patterns of the asperities under studied were wave stripes, line stripes, cylindrical pillars, square pillars, pentagonal pillars, hexagonal pillars, and octagonal pillars. All pillar shapes were arranged in square arrays, hexagonal arrays, and continuous stripes. The asperities sizes and the pitches were varied from 1 to 5 microm with 10 microm of asperity height. Then the patterned surfaces were coated with polydimethylsiloxane mixed with 10 wt% dicumylperoxide. It was found that the stripe asperities can generate only hydrophobic surface with water contact angle (WCA) of 135 degrees to 145 degrees. The pillars with square and hexagonal arrays had the WCA of 149 degrees to 158 degrees. The pentagonal pillars with square and hexagonal arrays achieved the highest WCA with an average WCA of 156 degrees. It was evident that the pillar shape had significant effect on the superhydrophobicity.

Evaluation of ferroelectric profile of poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) thin films by positive‐up–negative‐down and fatigue measurement

“…The variation of polarization within different samples and within the same sample can be attributed to the variation in thickness. The variation in thickness within the same sample may be due to edge bead formation and evaporation of solvent during spin coating 15,16 . The polarization profile reveals that the films are thinner at the center compared to the edges.…”

“…The variation in thickness within the same sample may be due to edge bead formation and evaporation of solvent during spin coating. 15,16 The polarization profile reveals that the films are thinner at the center compared to the edges. Most importantly ferroelectric switching characteristics are exhibited by all points along the diagonal.…”

Heterostructured Polymer‐Infiltrated Nanoparticle Films with Cavities via Capillary Rise Infiltration

“…Slightly different appearance in the corners of the Bragg reflectors are due to the thicker rim that forms during spin coating. [ 51 ] All scale bars for the optical images are 1 cm.…”

Impact of surface topography on the bacterial attachment to micro- and nano-patterned polymer films

“…We study the influence of wettability and hierarchical topography on the bacteria adhesion, while reporting a potentially industrial scalable manufacturing process with NIL patterned surfaces consisting of various topographies, one-level (micro, nano) and hierarchical (micro-and-nano) structures. The hierarchical structures were designed following the principles of Cassie-Baxter and Wenzel wettability models [37] , [38] , [39] , while thermal NIL was used as patterning technique. We show a distinct bacterial attachment of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria in unpatterned and patterned samples, while the hierarchical surfaces present a superior resistance to bacterial attachment as compared to one-level patterning comprised of micro or nanofeatures.…”