Nanotextured Silica Surfaces with Robust Superhydrophobicity and Omnidirectional Broadband Supertransmissivity

Park, Kyoo Chul; Choi, Hyeongrak; Chang, Chih‐Hao; Cohen, Robert E.; McKinley, Gareth H.; Barbastathis, George

doi:10.1021/nn301112t

Cited by 388 publications

(324 citation statements)

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“…First, the interspaces of the building blocks should be as small as possible, e.g., sub-micrometer scale, to avoid moisture penetration. [66][67][68][69] Second, their tip size should be as small as possible to minimize the interface adhesion. [31,50,51,[66][67][68][69] Third, the building blocks must have a certain height or depth to avoid the collapse of the suspended water bridges.…”

Section: Construction Rules Of Bionic Cmdsp Surfacesmentioning

confidence: 99%

“…[66][67][68][69] Second, their tip size should be as small as possible to minimize the interface adhesion. [31,50,51,[66][67][68][69] Third, the building blocks must have a certain height or depth to avoid the collapse of the suspended water bridges. [68] Following these design principles and inspired by nature, our group proposed and demonstrated that efficient self-propelling of small-scale condensed microdrops can be [5] Copyright 2007, Wiley-VCH.…”

Section: Construction Rules Of Bionic Cmdsp Surfacesmentioning

confidence: 99%

“…In principle, any sub-microscale structures with a small feature size (tip size and interspace) and a certain height (or depth) can become effective candidates for creating CMDSP surfaces. In fact, except for arrays of closely packed nanotips, including nanocones, [22,27,50,69,70] nanoneedles, [21,28,31,66,71] nanopencils, [23] and tip-like nanotubes, [72,73] other architectures such as nano wires, [24,74] nanosheet arrays, [20,29,62,75] nanorod-capped nano pores, [68,76] the porous structure of nanoparticles, [67] nanoparticle aggregates, [73,[77][78][79][80] and two-tier structures [25,57,63,[81][82][83][84][85][86][87][88][89] have all been verified to be effective in endowing material surfaces with the desired CMDSP functionality as long as they follow these basic construction rules.…”

Section: Construction Rules Of Bionic Cmdsp Surfacesmentioning

confidence: 99%

“…Benefiting from the wellestablished top-down micro-and nanofabrication technologies, various silicon nanostructures (e.g., nanoneedles [71,90] and nanocones [69] ) and their combination with regular microstructures (e.g., micropillars [25,85] and micropyramids [84] ) have been successively made for creating bionic CMDSP surfaces, and the transport behaviors of condensate microdrops at the microscale showing the typical coalescence-induced self-propelling details of condensed microdrops on the nanoneedle surface. f,g) Reproduced with permission.…”

Section: Metal-based Cmdsp Surfacesmentioning

confidence: 99%

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Recent Progress in Bionic Condensate Microdrop Self‐Propelling Surfaces

2017

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interest has focused on utilizing the lowadhesivity nature of superhydrophobic surfaces for the rapid removal of condensate microdrops, as this has significance in fundamental research and technological innovation. Example applications are the enhancement of condensation heat transfer for high-efficiency thermal management and energy utilization, [20][21][22][23][24][25] energy-effective antifreezing for airconditioner heat exchangers and aircraft wings, [26][27][28] and electrostatic energy harvesting. [29] In general, condensate drops on typical flat hydrophobic surfaces are only shed off under gravity when their sizes are comparable to the capillary length (≈2.7 mm for water), [30] which creates undesirable effects such as large thermal resistance [20][21][22][23][24][25] and the freezing of subcooled drops. [26][27][28] Clearly, a great challenge is the timely removal of condensate drops at the microscale where the gravitational effect does not work. The latest research has indicated that these small-scale condensate microdrops may self-remove via mutual coalescence as long as the coalescence-released excess surface energy is larger than the interface adhesion-induced energy dissipation. [31] Much effort has been devoted to exploring the utilization of knowledge of bionic low-adhesivity superhydrophobicity to develop innovative condensate microdrop self-propelling (CMDSP) surfaces. Different from traditional superhydrophobic surfaces, which are characterized by the bouncing or rolling off of deposited millimeter-size large drops, [32,33] CMDSP surfaces support the self-removal capability of smallscale condensate microdrops. It has been reported that classical superhydrophobic lotus leaves (Figure 1a), [34][35][36][37] as well as artificial surfaces consisting of hierarchical micro-and nanostructures, [38] one-tier microstructures, [39][40][41][42][43] or nanostructures [44,45] with larger characteristic interspaces, present a low-adhesivity property to the deposited water macrodrops, but become highly adhesive to condensed microdrops (Figure 1b). This is because moisture easily penetrates the microscale valleys or cavities. Clearly, superhydrophobic surfaces with irrationally designed surface structures can enhance the solid-liquid interfacial adhesion instead of promoting the rapid removal of condensed drops. Accordingly, it is still a challenge to design and fabricate very effective low-adhesivity superhydrophobic surfaces with the self-removal ability of condensate microdrops. Recently, there has been a large breakthrough in understanding the mechanism and construction rules of bionic CMDSP surfaces, leading to the exploration of fabrication methods for the surface functionalization of widely used metal materials and the Bionic condensate microdrop self-propelling (CMDSP) surfaces are attracting increased attention as novel, low-adhesivity superhydrophobic surfaces due to their value in fundamental research and technological innovation, e.g., for enhancing heat transfer, energy-effective antifreezing, and...

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Section: Construction Rules Of Bionic Cmdsp Surfacesmentioning

confidence: 99%

Section: Construction Rules Of Bionic Cmdsp Surfacesmentioning

confidence: 99%

Section: Construction Rules Of Bionic Cmdsp Surfacesmentioning

confidence: 99%

Section: Metal-based Cmdsp Surfacesmentioning

confidence: 99%

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Recent Progress in Bionic Condensate Microdrop Self‐Propelling Surfaces

2017

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“…For example, nanopatterned SiO 2 [48][49][50][51] may offer superior performance as an anti-reflective surface in the deep ultraviolet spectral range for applications in lasers, solar cells, etc, and as quantum nanostructures on III-V semiconductor surfaces [52][53][54] in optoelectronics and quantum optics. Moreover, according to available experimental and simulation data, pre-patterned surfaces have shown great potential for generating novel or highly ordered patterns, or even gratings [55][56][57][58].…”

Section: Introductionmentioning

confidence: 99%

Nanostructures on fused silica surfaces produced by ion beam sputtering with Al co-deposition

et al. 2017

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The ion beam sputtering (IBS) of smooth mono-elemental Si with impurity co-deposition is extended to a pre-rippled binary compound surface of fused silica (SiO 2 ). The dependence of the rms roughness and the deposited amount of Al on the distance from the Al source under Ar + IBS with Al co-deposition was investigated on smooth SiO 2 , pre-rippled SiO 2 , and smooth Si surfaces, using atomic force microscopy and X-ray photoelectron spectroscopy. Although the amounts of Al deposited on these three surfaces all decreased with increasing distance from the Al target, the morphology and rms roughness of the smooth Si surface did not demonstrate a strong distance dependence. In contrast to smooth Si, the rms roughness of both the smooth and pre-rippled SiO 2 surfaces exhibited a similar distance evolution trend of increasing, decreasing, and final stabilization at the distance where the results were similar to those obtained without Al co-deposition. However, the pre-rippled SiO 2 surfaces showed a stronger modulation of rms roughness than the smooth surfaces. At the incidence angles of 60° and 70°, dot-decorated ripples and roof-tiles were formed on the smooth SiO 2 surfaces, respectively, whereas nanostructures of closely aligned grains and blazed facets were generated on the pre-rippled SiO 2 , respectively. The combination of impurity co-deposition with pre-rippled surfaces was found to facilitate the formation of novel types of nanostructures and morphological growth. The initial ripples act as a template to guide the preferential deposition of Al on the tops of the ripples or the ripple sides facing the Al wedge, but not in the valleys between the ripples, leading to 2D grains and quasiblazed grating, which offer significant promise in optical applications. The rms roughness enhancement is attributed not to AlSi, but to AlO x F y compounds originating mainly from the Al source.

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