Highly durable and unidirectionally stooped polymeric nanohairs for gecko-like dry adhesive

Im, Hyeon Seong; Kwon, Ki Yoon; Kim, Jong Uk; Kim, Kwang Su; Yi, Hoon; Yoo, Pil J.; Pang, Changhyun; Jeong, Hoon Eui; Kim, Tae Il

doi:10.1088/0957-4484/26/41/415301

Cited by 17 publications

(18 citation statements)

References 21 publications

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“…The separated Au/h-Nanoturf membrane can maintain its morphological integrity and stability as a free-standing membrane (Figure 2a), since metal deposition on polymer nanostructures enhanced their effective mechanical modulus. [50] The free-standing membrane also conserved micro-holes, which are completely punctured to the bottom of the membrane. This can be confirmed by the formation of 20 µm-diameter circular Au dot patterns on the glass Figure S5, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Omnidirectional, Broadband Light Absorption in a Hierarchical Nanoturf Membrane for an Advanced Solar‐Vapor Generator

Kim

Kang

Lee

et al. 2020

Adv Funct Materials

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Solar‐thermal materials have been intensively studied in the context of production and localization of thermal energy, targeting an industry level application. Although photonic and optical strategies for enhancing light absorption have increased the efficiency of photo excitation/conversion into thermal energy, most of them have several limitations such as large area fabrication, thermal stability and broadband/omnidirectional light absorption. In this study, a gold‐coated hierarchical nanoturf membrane (Au/h‐Nanoturf membrane) incorporated with randomly distributed high aspect ratio (AR) nanostructures and micro‐through holes is proposed. The Au/h‐Nanoturf has peculiar black structures that provide advantages in forming a membrane with a large area and in absorbing broadband solar light spectrum. Furthermore, the membrane is combined with micro‐cone array which makes it exhibit exceptionally omnidirectional light absorption properties. Using computational analysis, it is confirmed that the micro‐cone array substantially contributes to the omnidirectional solar absorption irrespective of the wavelength. The optimized structural parameters for the maximum efficiency of the solar‐thermal materials are also found. The prepared solar‐vapor generator with the optimized structural features exhibits 91% average conversion efficiency under one sun condition. The efficiency is sustainable for up to four weeks. The highly efficient and omnidirectional broadband‐absorbing solar‐thermal membrane can be readily employed, targeting an industry level application.

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Section: Resultsmentioning

confidence: 99%

Omnidirectional, Broadband Light Absorption in a Hierarchical Nanoturf Membrane for an Advanced Solar‐Vapor Generator

Kim

Kang

Lee

et al. 2020

Adv Funct Materials

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“…The other hurdle is that low mechanical properties easily lead to nanohair collapse, causing hair-to-hair pairing or hair-to-bottom surface adhesion. Integration of a soft polymer and a stiff metal has emerged as a solution to this, as it increases the effective modulus of the hairs, as illustrated in Figure 5E–G [72]. Nanohairs and their backbone were fabricated with intrinsically soft materials, and their effective moduli can be enhanced by the deposition of metal.…”

Section: Limitations Of Tilted Nanohairs and New Strategies To Ovementioning

confidence: 99%

“…Enhanced durability and repeatability of micro/nanohairs. ( A ) Image of a sliding water droplet on microhair structures contaminated with ceramic microspheres; ( B ) SEM image of the boundary between ( C ) the self-cleaned area and ( D ) the contaminated area ( A – D : Reproduced from [21], with permission from the American Chemical Society); ( E ) Schematic illustration of thin-metal-coated nanohairs; ( F ) SEM image after a 10-cycle adhesion test; and ( G ) Pt-deposited nanohairs after a 100-cycle adhesion test ( E – G : Reproduced from [72], with permission from IOP publishing Ltd.); ( H ) SEM images of HDPE (top) and PP (bottom) after 0, 300, and 10,000 cycles; ( I ) Maximum shear force and normal force of HDPE and PP, respectively (H and I: Reproduced from [25], with permission from the American Chemical Society).…”

Section: Figurementioning

confidence: 99%

Process, Design and Materials for Unidirectionally Tilted Polymeric Micro/Nanohairs and Their Adhesion Characteristics

Kim

Han

et al. 2016

Polymers

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Recent research in the field of gecko-inspired dry adhesive has focused on modifying the material and structural properties of polymer-based nanohairs. Polymers such as polystyrene (PS), high-density polyethylene (HDPE), ultraviolet curable epoxy (SU-8), polyurethane acrylate (PUA), polycarbonate (PC), and polydimethyl siloxane (PDMS) can fulfill many mechanical property requirements, are easily tunable, and can be produced via large-scale fabrication. However, the fabrication process for tilted structure remains challenging. The tilted structure is a crucial factor in high-degree conformal contact, which facilitates high adhesion, low effective modulus, and directional adhesion properties. Recent studies have attempted to create a tilted structure by applying beam irradiation, mechanical and thermal stress, and magnetic fields. This review provides a comprehensive investigation into advanced strategies for producing tilted polymeric nanostructures and their potential applications in the near future.

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“…Many organisms in nature have a high adhesion force in their legs to enhance their ability to stick to different objects [1,2]. Additionally, scientists have discovered that a carbon nanotube array has the adhesive capacity of gecko lizards' feet.…”

Section: Introductionmentioning

confidence: 99%

The Study of Atomic Structure and Temperature Effects On Optimization of Carbon Nanotubes’ Adhesion Force With Dynamic Molecular Simulation

Molaei

Damircheli

2021

Preprint

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Carbon Nanotubes (CNTs) and their application in biomedical engineering, space robotics, or material development are fast-paced revolutionary fields. The key parameter in defining the strength and failure mechanisms of any CNT is their adhesion force capacity to different substrates. Therefore, it is of high importance to find the optimum geometrical and environmental conditions that can optimize the adhesion force for different types of CNTs. This comprehensive work presents the study of the effects of CNTs’ angle, length, diameter, temperature, chirality, and atomic defects on adhesion force. To systematically measure their effect on the adhesion force of CNTs, the single wall nanotube is simulated between two ideal graphene sheets. The simulation results show that the adhesion force increases as the angle, length, and diameter of various CNTs increase. Additionally, the temperature of the nanotubes plays a major role in the adhesion force. Adhesion force is maximized when the temperature is 300 K. Temperature can become a limiting factor on different applications of CNTs due to the atomic resonance and changes of the potential energies in their atoms. This study investigates the effect of chirality on different types of nanotubes. The results present that chirality has a higher effect on armchair-type nanotubes compared to other types. Moreover, the adhesion force of a nanotube with vacancies decreases by increasing the number of lost atoms. Thus, the adhesion force in an ideal nanotube with (11, 9) chirality is 6.14 nN. This is higher by 28%, 35%, 42%, and 53% compared to mono-vacancy, di-vacancy, tri-vacancy, and Stone-Wales defects if these defects are placed in the middle of nanotubes. Although there are extensive studies done in this field, the novelty of our work relies on the fact that different types of CNTs with different types of vacancies (with different locations) for different geometries are studied with the objective of enhancing adhesion force between CNT and graphene sheets.

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Highly durable and unidirectionally stooped polymeric nanohairs for gecko-like dry adhesive

Cited by 17 publications

References 21 publications

Omnidirectional, Broadband Light Absorption in a Hierarchical Nanoturf Membrane for an Advanced Solar‐Vapor Generator

Omnidirectional, Broadband Light Absorption in a Hierarchical Nanoturf Membrane for an Advanced Solar‐Vapor Generator

Process, Design and Materials for Unidirectionally Tilted Polymeric Micro/Nanohairs and Their Adhesion Characteristics

The Study of Atomic Structure and Temperature Effects On Optimization of Carbon Nanotubes’ Adhesion Force With Dynamic Molecular Simulation

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