Facile Method for Modulating the Profiles and Periods of Self-Ordered Three-Dimensional Alumina Taper-Nanopores

Li, Juan; Li, Congshan; Chen, Cheng; Hao, Qingli; Wang, Zhijia; Zhu, Jie; Gao, Xuefeng

doi:10.1021/am301603e

Cited by 49 publications

(50 citation statements)

References 35 publications

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“…Based on self-ordered anodicalumina-template-assisted nanoimprinting and etching, [91][92][93] polymer-based CMDSP surfaces mimicking the biological nanocone-array structure [50] have been also realized and used to highlight the necessity of sharpening tapered nanonipples to achieve desired CMDSP functionality. Similarly, various wetchemistry methods have been developed for the in situ growth of bionic CMDSP nanostructures on the surfaces of metal materials.…”

Section: Metal-based Cmdsp Surfacesmentioning

confidence: 99%

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: Metal-based Cmdsp Surfacesmentioning

confidence: 99%

Recent Progress in Bionic Condensate Microdrop Self‐Propelling Surfaces

2017

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“…It should be mentioned that a shape and geometrical features of the pores depend strongly on the duration time of anodization and etching steps. The method allows, thus, to design various profiles of columnar pores within the limits put by the interpore distance [23]. The length of the tapered pores and the interpore distance in the PAA membrane fabricated by the method presented in this work should be sufficient to prepare antireflective coatings with good performance in the IR spectral region.…”

Section: Resultsmentioning

confidence: 99%

“…Porous anodic alumina (PAA) is easy to prepare and allows for a precise manipulation of pore geometry within a broad range of dimensions [20]. The PAA with tapered pore structure and interpore distance D c in the range of 100 nm to 490 nm were previously fabricated [21][22][23][24]. The alumina taper-nanopores were used for preparing polymer AR coatings operating in visible and NIR range via template imprinting technique [18,25,26].…”

Section: Introductionmentioning

confidence: 99%

Manufacturing of highly ordered porous anodic alumina with conical pore shape and tunable interpore distance in the range of 550 nm to 650 nm

Norek

Łażewski

2017

Materials Science-Poland

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In this work, highly ordered porous anodic alumina (PAA) with tapered pore structure and interpore distance (D c ) in the range of 550 nm to 650 nm were fabricated. To produce hexagonal close-packed pore structure a two-step process, combining anodization in etidronic acid electrolyte in the first step and high-concentration, high-temperature anodization in citric acid electrolyte in the second step, was applied. The Al pre-patterned surface obtained in the first anodization was used to produce regular tapered pore arrays by subsequent and alternating anodization in 20 wt.% citric acid solution and pore wall etching in 10 wt.% phosphoric acid solution. The height of the tapered pores was ranging between 2.5 µm and 8.0 µm for the PAA with D c = 550 nm and D c = 650 nm, respectively. The geometry of the obtained graded structure can be used for a production of efficient antireflective coatings operating in IR spectral region.

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“…In order to obtain the tapered pore structure in AAO, the Al concaves were subjected to a multistep process of anodization in citric acid electrolyte and subsequent pore etching in 10 wt% phosphoric acid solution at room temperature, using similar approach to that presented in the previous works [21][22][23][24]. The process was repeated until the desired pore shape and AAO membrane thickness was obtained.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, AAOs with tapered pores and pitch size in the range of 100-490 nm were fabricated [21][22][23][24][25][26][27]. The tapered-pore AAO is very attractive porous material because it can act as a layer for the gradually changing refractive index.…”

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confidence: 99%