51
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Ouchi T, Yang J, Suo Z, Hayward RC. Effects of Stiff Film Pattern Geometry on Surface Buckling Instabilities of Elastic Bilayers. ACS APPLIED MATERIALS & INTERFACES 2018; 10:23406-23413. [PMID: 29956909 DOI: 10.1021/acsami.8b04916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Buckling instabilities-such as wrinkling and creasing-of micropatterned elastic surfaces play important roles in applications, including flexible electronics and microfluidics. In many cases, the spatial dimensions associated with the imposed pattern can compete with the natural length scale of the surface instabilities (e.g., the wrinkle wavelength), leading to a rich array of surface buckling behaviors. In this paper, we consider elastic bilayers consisting of a spatially patterned stiff film supported on a continuous and planar soft substrate. Through a combination of experimental and computational analyses, we find that three surface instability modes-wrinkling, Euler buckling, and rigid rotation-are observed for the stiff material patterns, depending on the in-plane dimensions of the film compared to the natural wrinkle wavelength, while the intervening soft regions undergo a creasing instability. The interplay between these instabilities leads to a variety of surface structures as a function of the pattern geometry and applied compressive strain, in many cases yielding contact between neighboring stiff material elements because of the formation of creases in the gaps between them.
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Affiliation(s)
- Tetsu Ouchi
- Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States
| | - Jiawei Yang
- School of Engineering and Applied Sciences, Kavli Institute for Bionano Science and Technology , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Zhigang Suo
- School of Engineering and Applied Sciences, Kavli Institute for Bionano Science and Technology , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Ryan C Hayward
- Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States
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52
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Progress toward reversible electrowetting on geometrically patterned superhydrophobic surfaces. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.01.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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53
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Visschers FLL, Hendrikx M, Zhan Y, Liu D. Liquid crystal polymers with motile surfaces. SOFT MATTER 2018; 14:4898-4912. [PMID: 29892763 DOI: 10.1039/c8sm00524a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In analogy with developments in soft robotics it is anticipated that soft robotic functions at surfaces of objects may have a large impact on human life with respect to comfort, health, medical care and energy. In this review, we demonstrate the possibilities and versatilities of liquid crystal networks and elastomers being explored for soft robotics, with an emphasis on motile surface properties, such as topographical dynamics. Typically the surfaces reversibly transfer from a flat state to a pre-designed corrugated state under various stimuli. But also reversible conversion between different corrugated states is feasible. Generally, the driving triggers are heat, light, electricity or contact with pH changing media. Also, the macroscopic effects of those dynamic topographies, such as altering the friction, wettability and/or performing work are illustrated. The review concludes with the existing challenges as well as outlook opportunities.
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Affiliation(s)
- Fabian L L Visschers
- Laboratory of Functional Organic Materials & Devices, Department of Chemical Engineering & Chemistry, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.
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54
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Zhou Z, Li Y, Guo TF, Guo X, Tang S. Surface Instability of Bilayer Hydrogel Subjected to Both Compression and Solvent Absorption. Polymers (Basel) 2018; 10:E624. [PMID: 30966658 PMCID: PMC6403687 DOI: 10.3390/polym10060624] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/01/2018] [Accepted: 06/03/2018] [Indexed: 11/16/2022] Open
Abstract
The bilayered structure of hard thin film on soft substrate can lose stability and form specific patterns, such as wrinkles or creases, on the surface, induced by external stimuli. For bilayer hydrogels, the surface morphology caused by the instability is usually controlled by the solvent-induced swelling/shrinking and mechanical force. Here, two important issues on the instability of bilayer hydrogels, which were not considered in the previous studies, are focused on in this study. First, the upper layer of a hydrogel is not necessarily too thin. Thus we investigated how the thickness of the upper layer can affect the surface morphology of bilayer hydrogels under compression through both finite element (FE) simulation and theoretical analysis. Second, a hydrogel can absorb water molecules before the mechanical compression. The effect of the pre-absorption of water before the mechanical compression was studied through FE simulations and theoretical analysis. Our results show that when the thickness of the upper layer is very large, surface wrinkles can exist without transforming into period doublings. The pre-absorption of the water can result in folds or unexpected hierarchical wrinkles, which can be realized in experiments through further efforts.
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Affiliation(s)
- Zhiheng Zhou
- College of Aerospace Engineering, Chongqing University, Chongqing 400017, China.
| | - Ying Li
- Department of Mechanical Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA.
| | - Tian Fu Guo
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore.
| | - Xu Guo
- State Key Laboratory of Structural Analysis for Industrial Equipment, International Research Center for Computational Mechanics, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116024, China.
| | - Shan Tang
- State Key Laboratory of Structural Analysis for Industrial Equipment, International Research Center for Computational Mechanics, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116024, China.
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55
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San Lim H, Lee SY, Lee NE, Cho SO. Patterning of Wrinkled Polymer Surfaces by Single-Step Electron Irradiation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5290-5296. [PMID: 29652508 DOI: 10.1021/acs.langmuir.8b00403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A novel yet simple approach to fabricate and pattern wrinkled surfaces on polymers is presented. Only by irradiating an electron beam onto a polymer, wrinkles are created on the polymer surface. Electron irradiation produces a bilayer polymeric structure comprising a degrading upper layer and a pristine bottom layer. Electron irradiation also increases the polymer surface temperature to a point much higher than the glass-transition temperature of the upper layer, leading to drastic thermal expansion of the upper layer. As a result, significant compressive force is applied to form surface wrinkles. The mechanism behind the wrinkle formation and the effects of electron irradiation parameters on the wrinkle characteristics are discussed. In addition, by this electron irradiation approach, a patterned wrinkle structure is uniquely prepared.
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Affiliation(s)
- Hyung San Lim
- Department of Nuclear and Quantum Engineering , Korea Advanced Institute of Science and Technology (KAIST) , 373-1 Guseong , Yuseong, Daejeon 305-701 , Republic of Korea
| | - Sang Yoon Lee
- Department of Nuclear and Quantum Engineering , Korea Advanced Institute of Science and Technology (KAIST) , 373-1 Guseong , Yuseong, Daejeon 305-701 , Republic of Korea
| | - Na Eun Lee
- Department of Nuclear and Quantum Engineering , Korea Advanced Institute of Science and Technology (KAIST) , 373-1 Guseong , Yuseong, Daejeon 305-701 , Republic of Korea
| | - Sung Oh Cho
- Department of Nuclear and Quantum Engineering , Korea Advanced Institute of Science and Technology (KAIST) , 373-1 Guseong , Yuseong, Daejeon 305-701 , Republic of Korea
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56
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Kwon D, Wooh S, Yoon H, Char K. Mechanoresponsive Tuning of Anisotropic Wetting on Hierarchically Structured Patterns. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:4732-4738. [PMID: 29595266 DOI: 10.1021/acs.langmuir.8b00496] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Here, we propose a simple mechanoresponsive system on patterned soft surfaces to manipulate both anisotropy and orientation of liquid wetting. On the poly(dimethylsiloxane) embedding line patterned structures, additional topographies, such as wrinkles and cracks, can be provided by applying compressive and tensile stress, respectively. This tunable hierarchy of structures with the different scales and directions of lines, wrinkles, and cracks allow the mechanoresponsive control of anisotropic wetting in a single platform. In addition, the wetting behavior on those surfaces is precisely investigated based on the concept of critical contact angle to overcome the ridges in a step flow.
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Affiliation(s)
| | - Sanghyuk Wooh
- School of Chemical Engineering & Materials Science , Chung-Ang University , Seoul 06974 , Republic of Korea
| | - Hyunsik Yoon
- Department of Chemical and Biomolecular Engineering , Seoul National University of Science & Technology , Seoul 01811 , Republic of Korea
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57
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Lin G, Zhang Q, Lv C, Tang Y, Yin J. Small degree of anisotropic wetting on self-similar hierarchical wrinkled surfaces. SOFT MATTER 2018; 14:1517-1529. [PMID: 29345710 DOI: 10.1039/c7sm02208e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We studied the wetting behavior of multiscale self-similar hierarchical wrinkled surfaces. The hierarchical surface was fabricated on poly(dimethylsiloxane) (PDMS) substrates by manipulating the sequential strain release and combined plasma/ultraviolet ozone (UVO) treatment. The generated structured surface shows an independently controlled dual-scale roughness with level-1 small-wavelength wrinkles (wavelength of 700-1500 nm and amplitude of 50-500 nm) resting on level-2 large-wavelength wrinkles (wavelength of 15-35 μm and amplitude of 3.5-5 μm), as well as accompanying orthogonal cracks. By tuning the aspect ratio of hierarchical wrinkles, the degree of wetting anisotropy in hierarchical wrinkled surfaces, defined as the contact angle difference between the parallel and perpendicular directions to the wrinkle grooves, is found to change between 3° and 9°. Through both experimental characterization (confocal fluorescence imaging) and theoretical analyses, we showed that the wetting state in the hierarchical wrinkled surface is in the Wenzel wetting state. We found that the measured apparent contact angle is larger than the theoretically predicted Wenzel contact angle, which is found to be attributed to the three-phase contact line pinning effect of both wrinkles and cracks that generates energetic barriers during the contact line motion. This is evidenced by the observed sudden drop of over 20° in the static contact angles along both perpendicular and parallel directions after slight vibration perturbation. Finally, we concluded that the observed small degree of wetting anisotropy in the hierarchical wrinkled surfaces mainly arises from the competition between orthogonal wrinkles and cracks in the contact line pinning.
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Affiliation(s)
- Gaojian Lin
- Applied Mechanics of Materials Laboratory, Department of Mechanical Engineering, Temple University, 1947 North 12th Street, Philadelphia, PA 19122, USA.
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58
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Parihar V, Bandyopadhyay S, Das S, Dasgupta S. Anisotropic Electrowetting on Wrinkled Surfaces: Enhanced Wetting and Dependency on Initial Wetting State. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:1844-1854. [PMID: 29309153 DOI: 10.1021/acs.langmuir.7b03467] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Electrowetting on dielectric (EWOD) on unidirectional microstructured surfaces has recently evoked significant interest as they can modulate the effect of electrowetting, and can thus find applications in directional wetting in microfluidic systems. However, the dependency of such EW phenomenon on their initial state of wetting and anisotropy is far from being well understood. The current study addresses the initial wetting states and their implication on the anisotropic electrowetting using a wrinkled EWOD platform. Herein we demonstrate a facile stampless and maskless structure generation technique to fabricate wrinkles of varying topography. Further, we have demonstrated alteration in the interfacial wetting conditions by modulating the wrinkle topography, and its effect on the droplet behavior during electrowetting. The capillary wicking-assisted electrowetting on these wrinkled surfaces is in specific direction dictated by the ordered wrinkles and prompts enhanced spreading of the droplet. We also demonstrate that while the enhancement of unidirectional electrowetting is stronger in conformal wetting state surfaces, composite wetting state surfaces depict a reversal in anisotropy.
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Affiliation(s)
- Vartika Parihar
- Department of Chemical Engineering, ‡Advanced Technology Development Centre, and §School of Medical Science and Technology, Indian Institute of Technology Kharagpur , Kharagpur-721302, West Bengal, India
| | - Saumyadwip Bandyopadhyay
- Department of Chemical Engineering, ‡Advanced Technology Development Centre, and §School of Medical Science and Technology, Indian Institute of Technology Kharagpur , Kharagpur-721302, West Bengal, India
| | - Soumen Das
- Department of Chemical Engineering, ‡Advanced Technology Development Centre, and §School of Medical Science and Technology, Indian Institute of Technology Kharagpur , Kharagpur-721302, West Bengal, India
| | - Sunando Dasgupta
- Department of Chemical Engineering, ‡Advanced Technology Development Centre, and §School of Medical Science and Technology, Indian Institute of Technology Kharagpur , Kharagpur-721302, West Bengal, India
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59
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Kim SJ, Kwon O, Kim DW, Kim J, Jung HT. Influence of graphene thickness and grain boundaries on MoS2 wrinkle nanostructures. Phys Chem Chem Phys 2018; 20:17000-17008. [DOI: 10.1039/c8cp02460j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, the influence of the graphene grain structure and thickness on the MoS2 wrinkle features were investigated.
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Affiliation(s)
- Seon Joon Kim
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering (BK-21 Plus)
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- South Korea
| | - Ohmin Kwon
- Department of Chemical and Biomolecular Engineering (BK-21 Plus)
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- South Korea
| | - Dae Woo Kim
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering (BK-21 Plus)
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- South Korea
| | - Jihan Kim
- Department of Chemical and Biomolecular Engineering (BK-21 Plus)
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- South Korea
- KAIST Institute for Nanocentury
| | - Hee-Tae Jung
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering (BK-21 Plus)
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- South Korea
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60
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He L, Sui X, Liang W, Wang Z, Akbarzadeh A. Numerical analysis of anisotropic wetting of chemically striped surfaces. RSC Adv 2018; 8:31735-31744. [PMID: 35548224 PMCID: PMC9085812 DOI: 10.1039/c8ra06626d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/03/2018] [Indexed: 12/25/2022] Open
Abstract
The stabilities and dynamic wetting behavior of anisotropic wetting are investigated using surface evolver.
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Affiliation(s)
- Liang He
- College of Aerospace and Civil Engineering
- Harbin Engineering University
- Harbin 150001
- China
- Department of Bioresource Engineering
| | - Xin Sui
- College of Aerospace and Civil Engineering
- Harbin Engineering University
- Harbin 150001
- China
| | - Wenyan Liang
- College of Aerospace and Civil Engineering
- Harbin Engineering University
- Harbin 150001
- China
| | - Zhenqing Wang
- College of Aerospace and Civil Engineering
- Harbin Engineering University
- Harbin 150001
- China
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61
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Zhan Y, Ruan M, Li W, Li H, Hu L, Ma F, Yu Z, Feng W. Fabrication of anisotropic PTFE superhydrophobic surfaces using laser microprocessing and their self-cleaning and anti-icing behavior. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.09.018] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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62
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Nolte AJ, Young Chung J, Davis CS, Stafford CM. Wrinkling-to-delamination transition in thin polymer films on compliant substrates. SOFT MATTER 2017; 13:7930-7937. [PMID: 29034929 PMCID: PMC5832036 DOI: 10.1039/c7sm01472d] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Compressing a thin, stiff film attached to a thick, compliant substrate can lead to a number of different modes of mechanical deformation depending upon the material properties of the system. In this article we explore direct transitions from surface wrinkling to buckle delamination, and provide a theoretical framework for understanding the conditions under which such transitions take place, as well as the resulting dimensions of the wrinkling-induced delamination. A key conclusion of this work is that the width of the delamination blister formed from a wrinkled film is relatively strain-independent, suggesting that delaminations can be used in such systems to measure the adhesion energy at the film-substrate interface. In addition, we demonstrate how the length and width of delaminations can be tailored through straightforward control of the substrate and film properties in the system, illustrating how wrinkling delaminations can be used for both thin film metrology and patterning applications.
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Affiliation(s)
- Adam J Nolte
- Materials Science and Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA.
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63
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Liang M, Chen X, Xu Y, Zhu L, Jin X, Huang C. Double-grooved nanofibre surfaces with enhanced anisotropic hydrophobicity. NANOSCALE 2017; 9:16214-16222. [PMID: 29043355 DOI: 10.1039/c7nr05188c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This study reports a facile method for fabricating double-grooved fibrous surfaces. The primary grooves of the surface are formed by aligned fibres, while the secondary grooves are achieved by oriented nanogrooves on the fibre surface. Investigation into the formation mechanism reveals that the nanogrooves can be readily tailored through adjusting the solvent ratio and relative humidity. With this understanding, a variety of polymers have been successfully electrospun into fibres having the same nanogrooved feature. These fibres show high resemblance to natural hierarchical structures, and thereby endowing the corresponding double-grooved surface with enhanced anisotropic hydrophobicity. A water droplet at a parallel direction to the grooves exhibits a much higher contact angle and a lower roll-off angle than the droplet at a perpendicular direction. The application potential of such anisotropic hydrophobicity has been demonstrated via a fog collection experiment, in which the double-grooved surface can harvest the largest amount of water. Moreover, the fabrication method requires neither post-treatment nor sophisticated equipment, making us anticipate that the double-grooved surface would be competitive in areas where a highly ordered surface, a large surface area and an anisotropic hydrophobicity are preferred.
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Affiliation(s)
- Meimei Liang
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620, China.
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64
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Wang J, Xie J, Zong C, Han X, Zhao J, Jiang S, Cao Y, Fery A, Lu C. Light-Modulated Surface Micropatterns with Multifunctional Surface Properties on Photodegradable Polymer Films. ACS APPLIED MATERIALS & INTERFACES 2017; 9:37402-37410. [PMID: 28981250 DOI: 10.1021/acsami.7b10573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Photodegradable polymers constitute an emerging class of materials that are expected to possess advances in the areas of micro/nano- and biotechnology. Herein, we report a green and effective strategy to fabricate light-responsive surface micropatterns by taking advantage of photodegradation chemistry. Thanks to the molecular chain breakage during the photolysis process, the stress field of photodegradable polymer-based wrinkling systems undergoes continuous disturbance, leading to the release/reorganization of the internal stress. Revealed by systematic experiments, the light-induced stress release mechanism enables the dynamic adaption of not only thermal-induced labyrinth wrinkles, but uniaxially oriented wrinkle microstructures induced by mechanical straining. This method paves the way for their diverse applications, for example, in optical information display and storage, and the smart fabrication of multifunctional surfaces as demonstrated here.
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Affiliation(s)
- Juanjuan Wang
- School of Materials Science and Engineering, Tianjin University , Tianjin, 300072, P. R. China
| | - Jixun Xie
- School of Materials Science and Engineering, Tianjin University , Tianjin, 300072, P. R. China
| | - Chuanyong Zong
- School of Materials Science and Engineering, Tianjin University , Tianjin, 300072, P. R. China
| | - Xue Han
- School of Materials Science and Engineering, Tianjin University , Tianjin, 300072, P. R. China
| | - Jingxin Zhao
- School of Materials Science and Engineering, Tianjin University , Tianjin, 300072, P. R. China
| | - Shichun Jiang
- School of Materials Science and Engineering, Tianjin University , Tianjin, 300072, P. R. China
| | - Yanping Cao
- AML, Department of Engineering Mechanics, Tsinghua University , Beijing, 100084, P. R. China
| | - Andreas Fery
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden e.V. , D-01069 Dresden, Germany
| | - Conghua Lu
- School of Materials Science and Engineering, Tianjin University , Tianjin, 300072, P. R. China
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65
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Lin IT, Wang T, Zhang F, Smoukov SK. Fault-Tolerant Electro-Responsive Surfaces for Dynamic Micropattern Molds and Tunable Optics. Sci Rep 2017; 7:12481. [PMID: 28970531 PMCID: PMC5624962 DOI: 10.1038/s41598-017-12899-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 09/07/2017] [Indexed: 11/08/2022] Open
Abstract
Electrically deformable surfaces based on dielectric elastomers have recently demonstrated controllable microscale roughness, ease of operation, fast response, and possibilities for programmable control. Potential applications include marine anti-biofouling, dynamic pattern generation, and voltage-controlled smart windows. Most of these systems, however, exhibit limited durability due to irreversible dielectric breakdown. Lowering device voltage to avoid this issue is hindered by an inadequate understanding of the electrically-induced wrinkling deformation as a function of the deformable elastic film thickness. Here we report responsive surfaces that overcome these shortcomings: we achieve fault-tolerant behavior based on the ability to self-insulate breakdown faults, and we enhance fundamental understanding of the system by quantifying the critical field necessary to induce wrinkles in films of different thickness and comparing to analytical models. We also observe new capabilities of these responsive surfaces, such as field amplification near local breakdown sites, which enable actuation and wrinkle pattern formation at lower applied voltages. We demonstrate the wide applicability of our responsive, fault-tolerant films by using our system for adjustable transparency films, tunable diffraction gratings, and a dynamic surface template/factory from which various static micropatterns can be molded on demand.
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Affiliation(s)
- I-Ting Lin
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, United Kingdom
| | - Tiesheng Wang
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, United Kingdom
| | - Fenghua Zhang
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, United Kingdom
- Centre for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150080, People's Republic of China
| | - Stoyan K Smoukov
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, United Kingdom.
- School of Engineering and Materials Science, Queen Mary University of London, London, E1 4NS, United Kingdom.
- Department of Chemical and Pharmaceutical Engineering, Sofia University, Sofia, 1164, Bulgaria.
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66
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Zhou Z, Li Y, Wong W, Guo T, Tang S, Luo J. Transition of surface-interface creasing in bilayer hydrogels. SOFT MATTER 2017; 13:6011-6020. [PMID: 28782771 DOI: 10.1039/c7sm01013c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Controlling the morphologies and properties of the surface and/or interface of bimaterials consisting of soft polymers provides new opportunities in many engineering applications. Crease is a widely observed deformation mode in nature and engineering applications for soft polymers where the smooth surface folds into a region of self-contact with a sharp tip, usually induced by the instability from mechanical compression or swelling. In this work, we explore the competition mechanisms between surface and interface creases through numerical simulations and experimental studies on bilayer hydrogels. The surface or interface crease of the bilayer hydrogels under swelling is governed by both the modulus ratio (M2/M1) and the height ratio (H2/H1). Through extensive numerical simulations, we find that the interface crease of the bilayer hydrogels can only occur at a moderate modulus ratio (24 < M2/M1 < 96) and a large height ratio (H2/H1 ≥ 8). Guided by this phase diagram, our experiments confirm that both surface and interface creases can be generated by swelling triggered instability, and the transition of surface to interface creases occurs at the critical value of the height ratio (H2/H1) between 5 and 10. Such an observation is in good agreement with our numerical predictions. Fundamental understandings on the switching between the surface and interface creases provide new insights into the design of highly tunable soft materials and devices over a wide range of length scales.
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Affiliation(s)
- Zhiheng Zhou
- College of Aerospace Engineering, Chongqing University, Chongqing, 400044, China
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67
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Chen CH, Chen SH, Kuo CY, Li ML, Chen JP. Response of Dermal Fibroblasts to Biochemical and Physical Cues in Aligned Polycaprolactone/Silk Fibroin Nanofiber Scaffolds for Application in Tendon Tissue Engineering. NANOMATERIALS (BASEL, SWITZERLAND) 2017; 7:E219. [PMID: 28800110 PMCID: PMC5575701 DOI: 10.3390/nano7080219] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 08/04/2017] [Accepted: 08/06/2017] [Indexed: 01/12/2023]
Abstract
Silk fibroin (SF) and fiber alignment were introduced into polycaprolactone (PCL)-based electrospun nanofibers as chemical and physical cues for tendon tissue engineering applications. The physicochemical properties of random PCL (RP) nanofibers, random PCL/SF (RPSF) nanofibers and aligned PCL/SF (APSF) nanofibers were characterized for fiber orientation and SF blending effects. An in vitro cell culture with rabbit dermal fibroblasts (RDFBs) on nanofibers indicated that SF promotes cell proliferation to a higher extent than fiber alignment. Cells aligned in the direction of fiber axes could be confirmed through scanning electron microscopy (SEM) observation and cytoskeleton staining. The quantitative real-time polymerase chain reaction (qRT-PCR) experiments indicated up-regulated gene expression of tendon marker proteins (type I collagen (Col I), fibronectin and biglycan) on APSF nanofibers and tendon reconstruction was confirmed from Col III gene expression. Animal experiments with Achilles tendon defect repairs in rabbits were carried out with RPSF and APSF scaffolds. The beneficial effects of fiber alignment were verified from histological and immunohistochemical staining, where cell migration and extracellular matrix protein deposition tend to stretch in a parallel direction along the axial direction of APSF nanofibers with enhanced Col I and tenascin C production. Biomechanical testing indicated the tensile stiffness and maximum load of cell-seeded APSF scaffolds were 60.2 and 81.3% of normal tendon values, respectively, which are significantly higher than cell-seeded RPSF or acellular APSF and RPSF scaffolds. These results suggest that APSF nanofiber scaffolds combined with RDFBs have the potential to repair the gap defects of Achilles tendons in vivo and to effectively restore the function and structure of tendons.
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Affiliation(s)
- Chih-Hao Chen
- Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
- Department of Plastic and Reconstructive Surgery and Craniofacial Research Center, Chang Gung Memorial Hospital, Kwei-San, Taoyuan 33305, Taiwan.
| | - Shih-Hsien Chen
- Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
| | - Chang-Yi Kuo
- Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
| | - Meng-Lun Li
- Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
| | - Jyh-Ping Chen
- Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
- Department of Plastic and Reconstructive Surgery and Craniofacial Research Center, Chang Gung Memorial Hospital, Kwei-San, Taoyuan 33305, Taiwan.
- Institute Research Center for Chinese Herbal Medicine and Research Center for Food and Cosmetic Safety, College of Human Ecology, Chang Gung University of Science and Technology, Kwei-San, Taoyuan 33302, Taiwan.
- Department of Materials Engineering, Ming Chi University of Technology, Tai-Shan, New Taipei City 24301, Taiwan.
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68
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Lin G, Chandrasekaran P, Lv C, Zhang Q, Tang Y, Han L, Yin J. Self-similar Hierarchical Wrinkles as a Potential Multifunctional Smart Window with Simultaneously Tunable Transparency, Structural Color, and Droplet Transport. ACS APPLIED MATERIALS & INTERFACES 2017; 9:26510-26517. [PMID: 28702991 DOI: 10.1021/acsami.7b05056] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Smart window has immense potential for energy savings in architectural and vehicular applications, while most studies focus on the tunability of a single property of optical transmittance. Here we explore harnessing dynamically tunable hierarchical wrinkles for design of a potential multifunctional smart window with combined structural color and water droplet transport control. The self-similar hierarchical wrinkles with both nanoscale and microscale features are generated on a prestrained poly(dimethylsiloxane) elastomer through sequential strain release and multistep oxygen plasma treatment. We show that the hierarchically wrinkled elastomer displays both opaqueness and iridescent structural color. We find that restretching/releasing the elastomer leads to the reversible and repeatable switch from opaqueness to transparency, arising from the flattening of large wrinkles (micrometer scale), while a nonvanishing structural color occurs due to the nondisappearing small wrinkles (nanoscale). The unique features of combined reversible large wrinkles and irreversible small wrinkles during hierarchical wrinkling are well reproduced by corresponding finite element simulation. The criteria for generating self-similar hierarchical wrinkles is revealed through a simplified theoretical model and validated by experiments. In addition to its tunable optical property, we further show its ability in control of water droplet transport on demand through mechanical stretching and release. We find that an initially pinned water droplet on the tilted hierarchically wrinkled surface starts to slide when the surface is stretched, and becomes pinned again upon strain release. Such a process is reversible and repeatable. The hierarchically wrinkled surface could find broad potential applications not only in multifunctional smart windows with additional features of aesthetics and water collection, but in microfluidics, design of slippery surfaces, and directional water transportation.
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Affiliation(s)
- Gaojian Lin
- Applied Mechanics of Materials Laboratory, Department of Mechanical Engineering Temple University , 1947 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - Prashant Chandrasekaran
- School of Biomedical Engineering Science and Health Systems, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Cunjing Lv
- Center of Smart Interfaces, Technische Universität Darmstadt , Alarich-Weiss-Straße 10, 64287 Darmstadt, Germany
| | - Qiuting Zhang
- Applied Mechanics of Materials Laboratory, Department of Mechanical Engineering Temple University , 1947 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - Yichao Tang
- Applied Mechanics of Materials Laboratory, Department of Mechanical Engineering Temple University , 1947 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - Lin Han
- School of Biomedical Engineering Science and Health Systems, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - Jie Yin
- Applied Mechanics of Materials Laboratory, Department of Mechanical Engineering Temple University , 1947 North 12th Street, Philadelphia, Pennsylvania 19122, United States
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69
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Ge P, Wang S, Liu Y, Liu W, Yu N, Zhang J, Shen H, Zhang J, Yang B. Autonomous Control of Fluids in a Wide Surface Tension Range in Microfluidics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7248-7255. [PMID: 28681601 DOI: 10.1021/acs.langmuir.7b01934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, we report the preparation of anisotropic wetting surfaces that could control various wetting behaviors of liquids in a wide surface tension range (from water to oil), which could be employed as a platform for controlling the flow of liquids in microfluidics (MFs). The anisotropic wetting surfaces are chemistry-asymmetric "Janus" silicon cylinder arrays, which are fabricated via selecting and regulating the functional groups on the surface of each cylinder unit. Liquids (in a wide surface tension range) wet in a unidirectional manner along the direction that was modified by the group with large surface energy. Through introducing the Janus structure into a T-shaped pattern and integrating it with an identical T-shaped poly(dimethylsiloxane) microchannel, the as-prepared chips can be utilized to perform as a surface tension admeasuring apparatus or a one-way valve for liquids in a wide surface tension range, even oil. Furthermore, because of the excellent ability in controlling the flowing behavior of liquids in a wide surface tension range in an open system or a microchannel, the anisotropic wetting surfaces are potential candidates to be applied both in open MFs and conventional MFs, which would broaden the application fields of MFs.
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Affiliation(s)
- Peng Ge
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Shuli Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Yongshun Liu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences , Changchun 130033, P. R. China
| | - Wendong Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Nianzuo Yu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Jianglei Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Huaizhong Shen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Junhu Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Bai Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
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70
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Jun K, Kim D, Ryu S, Oh IK. Surface Modification of Anisotropic Dielectric Elastomer Actuators with Uni- and Bi-axially Wrinkled Carbon Electrodes for Wettability Control. Sci Rep 2017; 7:6091. [PMID: 28729661 PMCID: PMC5519688 DOI: 10.1038/s41598-017-06274-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 06/12/2017] [Indexed: 11/09/2022] Open
Abstract
Interest in soft actuators for next-generation electronic devices, such as wearable electronics, haptic feedback systems, rollable flexible displays, and soft robotics, is rapidly growing. However, for more practical applications in diverse electronic devices, soft actuators require multiple functionalities including anisotropic actuation in three-dimensional space, active tactile feedback, and controllable wettability. Herein, we report anisotropic dielectric elastomer actuators with uni- and bi-axially wrinkled carbon black electrodes that are formed through pre-streching and relaxation processes. The wrinkled dielectric elastomer actuator (WDEA) that shows directional actuation under electric fields is used to control the anisotropic wettability. The morphology changes of the electrode surfaces under various electric stimuli are investigated by measuring the contact angles of water droplets, and the results show that the controllable wettability has a broad range from 141° to 161° along the wrinkle direction. The present study successfully demonstrates that the WDEA under electrically controlled inputs can be used to modulate the uni- or bi-axially wrinkled electrode surfaces with continous roughness levels. The controllable wrinkled structures can play an important role in creating adaptable water repellency and tunable anisotropic wettability.
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Affiliation(s)
- Kiwoo Jun
- Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Donggyu Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Seunghwa Ryu
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Il-Kwon Oh
- Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea.
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71
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Schauer S, Worgull M, Hölscher H. Bio-inspired hierarchical micro- and nano-wrinkles obtained via mechanically directed self-assembly on shape-memory polymers. SOFT MATTER 2017; 13:4328-4334. [PMID: 28504298 DOI: 10.1039/c7sm00154a] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Inspired by complex multi-functional leaf and petal surfaces, we introduce a mechanically directed self-assembly process to create linearly oriented micro- and nanosized surface wrinkles in an all-polymer bi-layer system based on a shape-memory polymer substrate. By systematically investigating the influence of coating thickness and substrate programming strain on wrinkle period and height, we reveal how to control the structure size from a few hundred nanometers up to several microns. As a parameter unique to shape memory polymers, we demonstrate that the temperature during the recovery process can also be utilized to tailor the structure dimensions. Furthermore, we advance the method with a second structuring step to mimic the hierarchically structured petal surfaces of tulips and daisies. The presented structuring method provides a large-scale, mold-free, and very cost-effective way for the full-polymer fabrication of micro and sub-microstructures with adjustable structure size and intrinsic irregularity.
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Affiliation(s)
- Senta Schauer
- Institute of Microstructure Technology, Karlsruher Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
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72
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Ibru T, Kalaitzidou K, Baldwin JK, Antoniou A. Stress-induced surface instabilities and defects in thin films sputter deposited on compliant substrates. SOFT MATTER 2017; 13:4035-4046. [PMID: 28517009 DOI: 10.1039/c7sm00340d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Existing analyses predict that thin metal films deposited on compliant substrates are subject to a variety of surface instabilities, such as wrinkles, folds, creases, etc., that become more prominent with increased compressive residual stress. Under compressive stress, cracks have been assumed to form only when the interfacial strength is weak, allowing the film to detach from the substrate. In this work, we demonstrate that cracks also form on surfaces under compressive mismatch strain when the interface is strong. In particular, we consider metal alloy films sputter deposited under bias on elastomers with different thicknesses, curing temperatures or surface treatments. The deposition parameters created residual compressive strains and strong adhesion in the bilayers. Samples without surface treatment formed wrinkles and through-thickness cracks at 0.25-0.4% mismatch strains. Only through-thickness cracks were observed in UV treated samples. The crack spacing was found to decrease by a factor of 4 when the surface was UV treated and by a factor of 3 as the elastomer thickness decreased from 30 to 6 μm. Cracks penetrated through the elastomer, 15-30 times deeper than the film thickness, and formed in all samples with a brittle coating. A numerical model was developed to explain the formation of through-thickness cracks and wrinkles under applied compressive mismatch strains. The model suggests that cracks can initiate from the peak of wrinkles when the critical fracture strength of the coating is exceeded. For the UV treated samples, through-thickness cracks are possibly impacted by the formation of an embrittled near surface PDMS layer.
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Affiliation(s)
- Timothy Ibru
- G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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73
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Azad MAK, Krause T, Danter L, Baars A, Koch K, Barthlott W. Fog Collection on Polyethylene Terephthalate (PET) Fibers: Influence of Cross Section and Surface Structure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5555-5564. [PMID: 28260383 DOI: 10.1021/acs.langmuir.7b00478] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Fog-collecting meshes show a great potential in ensuring the availability of a supply of sustainable freshwater in certain arid regions. In most cases, the meshes are made of hydrophilic smooth fibers. Based on the study of plant surfaces, we analyzed the fog collection using various polyethylene terephthalate (PET) fibers with different cross sections and surface structures with the aim of developing optimized biomimetic fog collectors. Water droplet movement and the onset of dripping from fiber samples were compared. Fibers with round, oval, and rectangular cross sections with round edges showed higher fog-collection performance than those with other cross sections. However, other parameters, for example, width, surface structure, wettability, and so forth, also influenced the performance. The directional delivery of the collected fog droplets by wavy/v-shaped microgrooves on the surface of the fibers enhances the formation of a water film and their fog collection. A numerical simulation of the water droplet spreading behavior strongly supports these findings. Therefore, our study suggests the use of fibers with a round cross section, a microgrooved surface, and an optimized width for an efficient fog collection.
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Affiliation(s)
- M A K Azad
- Nees Institute for Biodiversity of Plants, Rheinische Friedrich-Wilhelms-University , 53115 Bonn, Germany
| | - Tobias Krause
- Nees Institute for Biodiversity of Plants, Rheinische Friedrich-Wilhelms-University , 53115 Bonn, Germany
- Department of Mechanical Engineering, Westphalian University of Applied Sciences , 46397 Bocholt, Germany
| | - Leon Danter
- Department of Biomimetics, Faculty of Nature and Technique, Bremen University of Applied Sciences , 28199 Bremen, Germany
| | - Albert Baars
- Department of Biomimetics, Faculty of Nature and Technique, Bremen University of Applied Sciences , 28199 Bremen, Germany
| | - Kerstin Koch
- Faculty of Life Sciences, Rhine-Waal University of Applied Sciences , 47533 Kleve, Germany
| | - Wilhelm Barthlott
- Nees Institute for Biodiversity of Plants, Rheinische Friedrich-Wilhelms-University , 53115 Bonn, Germany
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74
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Rhee D, Lee W, Odom TW. Crack‐Free, Soft Wrinkles Enable Switchable Anisotropic Wetting. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701968] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Dongjoon Rhee
- Department of Materials Science and Engineering Northwestern University 2220 Campus Drive Evanston IL 60208 USA
| | - Won‐Kyu Lee
- Department of Materials Science and Engineering Northwestern University 2220 Campus Drive Evanston IL 60208 USA
| | - Teri W. Odom
- Department of Materials Science and Engineering Northwestern University 2220 Campus Drive Evanston IL 60208 USA
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
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75
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Rhee D, Lee W, Odom TW. Crack‐Free, Soft Wrinkles Enable Switchable Anisotropic Wetting. Angew Chem Int Ed Engl 2017; 56:6523-6527. [DOI: 10.1002/anie.201701968] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/23/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Dongjoon Rhee
- Department of Materials Science and Engineering Northwestern University 2220 Campus Drive Evanston IL 60208 USA
| | - Won‐Kyu Lee
- Department of Materials Science and Engineering Northwestern University 2220 Campus Drive Evanston IL 60208 USA
| | - Teri W. Odom
- Department of Materials Science and Engineering Northwestern University 2220 Campus Drive Evanston IL 60208 USA
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
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76
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Wu H, Zhu K, Cao B, Zhang Z, Wu B, Liang L, Chai G, Liu A. Smart design of wettability-patterned gradients on substrate-independent coated surfaces to control unidirectional spreading of droplets. SOFT MATTER 2017; 13:2995-3002. [PMID: 28367564 DOI: 10.1039/c6sm02864k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Highly adherent wettability patterns on the substrate-independent superhydrophobic surfaces of trimethoxyoctadecylsilane modified titanium dioxide (TiO2)-based coatings were prepared by using commercial photolithography. Three custom unidirectional channels with gradient wettability patterns were obtained by spatially selective wettability conversion from superhydrophobic to superhydrophilic when the coatings were exposed to ultraviolet light (∼365 nm). The movement behavior of droplets on these unidirectional channels was studied and the displacement of droplet movement was effectively controlled. Integrating the idea of gradient wettability patterns into planar microfluidic devices (microreactors), a self-driven fluid transport was achieved to realize droplet metering, merging or reaction, and rapid transport. This self-driven fluid transport with gradient wettability patterns has great potential in fabricating a new category of pump-free microfluidic systems that can be used in various conditions.
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Affiliation(s)
- Huaping Wu
- Key Laboratory of E&M (Zhejiang University of Technology), Ministry of Education & Zhejiang Province, Hangzhou 310014, China.
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77
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Godaba H, Zhang ZQ, Gupta U, Chiang Foo C, Zhu J. Dynamic pattern of wrinkles in a dielectric elastomer. SOFT MATTER 2017; 13:2942-2951. [PMID: 28357441 DOI: 10.1039/c7sm00198c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A membrane of a dielectric elastomer may undergo electromechanical phase transition from the flat to wrinkled state, when the applied voltage reaches a critical value. The wrinkled region is observed to expand at the expense of the flat region during the phase transition. In this paper, we report on a dynamic pattern of wrinkles in a circular membrane of a dielectric elastomer. During phase transition, both the flat and wrinkled regions move interchangeably in the membrane. The radial prestretch is found to significantly affect electromechanical phase transition. For example, a membrane with a small prestretch can exhibit a dynamic pattern of wrinkles, which is essentially related to snap-through instability. However, a membrane with a large prestretch undergoes continuous phase transition, without exhibiting a dynamic pattern. An analytical model is developed to interpret these experimental phenomena. Finite element simulations are performed to predict the wrinkle morphology, especially the coexistence of flat and wrinkled regions. Both the theoretical calculations and finite element simulations are qualitatively consistent with the experiments. Additionally, we observe another type of electromechanical behavior involving a dynamic pattern of wrinkles with different wavelengths. The membrane first undergoes continuous transition from the flat to wrinkled state, followed by discontinuous transition from one wrinkled state to another. These results may inspire new applications for dielectric elastomers such as on-demand patterning of wrinkles for microfluidics and stretchable electronics.
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Affiliation(s)
- Hareesh Godaba
- Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576.
| | - Zhi-Qian Zhang
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632
| | - Ujjaval Gupta
- Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576.
| | - Choon Chiang Foo
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632
| | - Jian Zhu
- Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576.
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78
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Ge P, Wang S, Liu W, Wang T, Yu N, Ye S, Shen H, Wu Y, Zhang J, Yang B. Unidirectional Wetting of Liquids on "Janus" Nanostructure Arrays under Various Media. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2177-2184. [PMID: 28195733 DOI: 10.1021/acs.langmuir.7b00034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report the unidirectional wetting behavior of liquids (water and oil) on Janus silicon cylinder arrays (Si-CAs) under various media (air, water, and oil). The Janus cylinders were prepared by chemical modification of nanocylinders with different molecules on two sides. Through adjusting surface energies of the modified molecules, the as-prepared surfaces could control the wetting behavior of different types of liquids under various media. We discuss the regularity systematically and propose a strategy for preparing anisotropic wetting surfaces under arbitrary media. That is, to find two surface modification molecules with different surface energies, one of the molecules is easy to be wetted by the liquid under the corresponding media, while the other one is difficult. Additionally, by introducing thermal-responsive polymer brushes onto one part of Janus Si-CAs, the surfaces show thermal-responsive anisotropic wetting property under various media. We believe that due to the excellent unidirectional wettability under various media, the Janus surfaces could be applied in water/oil transportation, oil-repellent and self-cleaning coatings, water/oil separation, microfluidics, and so on.
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Affiliation(s)
- Peng Ge
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Shuli Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Wendong Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Tieqiang Wang
- Research Center for Molecular Science and Engineering, Northeastern University , Shenyang 110004, P. R. China
| | - Nianzuo Yu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Shunsheng Ye
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Huaizhong Shen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Yuxin Wu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Junhu Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Bai Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
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79
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Yang J, Damle S, Maiti S, Velankar SS. Stretching-induced wrinkling in plastic-rubber composites. SOFT MATTER 2017; 13:776-787. [PMID: 28054062 DOI: 10.1039/c6sm01823h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We examine the mechanics of three-layer composite films composed of an elastomeric layer sandwiched between two thin surface layers of plastic. Upon stretching and releasing such composite films, they develop a highly wrinkled surface texture. The mechanism for this texturing is that during stretching, the plastic layers yield and stretch irreversibly whereas the elastomer stretches reversibly. Thus upon releasing, the plastic layers buckle due to compressive stress imposed by the elastomer. Experiments are conducted using SEPS elastomer and 50 micron thick LLDPE plastic films. Stretching and releasing the composites to 2-5 times their original length induces buckles with wavelength on the order of 200 microns, and the wavelength decreases as the stretching increases. FEM simulations reveal that plastic deformation is involved at all stages during this process: (1) during stretching, the plastic layer yields in tension; (2) during recovery, the plastic layer first yields in-plane in compression and then buckles; (3) post-buckling, plastic hinges are formed at high-curvature regions. Homogeneous wrinkles are predicted only within a finite window of material properties: if the yield stress is too low, the plastic layers yield in-plane, without wrinkling, whereas if the yield stress is too high, non-homogeneous wrinkles are predicted. This approach to realizing highly wrinkled textures offers several advantages, most importantly the fact that high aspect ratio wrinkles (amplitude to wavelength ratios exceeding 0.4) can be realized.
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Affiliation(s)
- Junyu Yang
- Dept. of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA.
| | - Sameer Damle
- Dept. of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA.
| | - Spandan Maiti
- Dept. of Biomedical Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Sachin S Velankar
- Dept. of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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80
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Abstract
This review systematically summarizes the recent developments of superoleophobic surfaces, focusing on their design, fabrication, characteristics, functions, and important applications.
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Affiliation(s)
- Jiale Yong
- State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information
- School of Electronics & Information Engineering
- Xi’an Jiaotong University
- Xi’an
- P. R. China
| | - Feng Chen
- State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information
- School of Electronics & Information Engineering
- Xi’an Jiaotong University
- Xi’an
- P. R. China
| | - Qing Yang
- School of Mechanical Engineering
- Xi’an Jiaotong University
- Xi’an
- P. R. China
| | - Jinglan Huo
- State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information
- School of Electronics & Information Engineering
- Xi’an Jiaotong University
- Xi’an
- P. R. China
| | - Xun Hou
- State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information
- School of Electronics & Information Engineering
- Xi’an Jiaotong University
- Xi’an
- P. R. China
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81
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Lacombe J, Soulié-Ziakovic C. Controlling self-patterning of acrylate films by photopolymerization. Polym Chem 2017. [DOI: 10.1039/c6py02072k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Acrylate formulations can spontaneously generate surface patterns by UV-curing in open-air.
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Affiliation(s)
- J. Lacombe
- Laboratoire Matière Molle et Chimie
- UMR 7167 CNRS-ESPCI Paris
- Ecole Supérieure de Physique et de Chimie Industrielles de la Ville de Paris
- PSL Research University
- Paris
| | - C. Soulié-Ziakovic
- Laboratoire Matière Molle et Chimie
- UMR 7167 CNRS-ESPCI Paris
- Ecole Supérieure de Physique et de Chimie Industrielles de la Ville de Paris
- PSL Research University
- Paris
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82
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Yunusa M, Ozturk FE, Yildirim A, Tuvshindorj U, Kanik M, Bayindir M. Bio-inspired hierarchically structured polymer fibers for anisotropic non-wetting surfaces. RSC Adv 2017. [DOI: 10.1039/c6ra28111g] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A rice leaf-like hierarchically textured polymer fiber arrays for anisotropic non-wetting surfaces.
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Affiliation(s)
- M. Yunusa
- UNAM – National Nanotechnology Research Center
- Turkey
- Institute of Materials Science and Nanotechnology
- Turkey
| | - F. E. Ozturk
- UNAM – National Nanotechnology Research Center
- Turkey
- Institute of Materials Science and Nanotechnology
- Turkey
| | - A. Yildirim
- UNAM – National Nanotechnology Research Center
- Turkey
- Institute of Materials Science and Nanotechnology
- Turkey
| | - U. Tuvshindorj
- UNAM – National Nanotechnology Research Center
- Turkey
- Institute of Materials Science and Nanotechnology
- Turkey
| | - M. Kanik
- UNAM – National Nanotechnology Research Center
- Turkey
- Institute of Materials Science and Nanotechnology
- Turkey
| | - M. Bayindir
- UNAM – National Nanotechnology Research Center
- Turkey
- Institute of Materials Science and Nanotechnology
- Turkey
- Department of Physics
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83
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Kim D, Pugno NM, Ryu S. Wetting theory for small droplets on textured solid surfaces. Sci Rep 2016; 6:37813. [PMID: 27897194 PMCID: PMC5126673 DOI: 10.1038/srep37813] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 11/02/2016] [Indexed: 11/08/2022] Open
Abstract
Conventional wetting theories on rough surfaces with Wenzel, Cassie-Baxter, and Penetrate modes suggest the possibility of tuning the contact angle by adjusting the surface texture. Despite decades of intensive study, there are still many experimental results that are not well understood because conventional wetting theory, which assumes an infinite droplet size, has been used to explain measurements of finite-sized droplets. Here, we suggest a wetting theory applicable to a wide range of droplet size for the three wetting modes by analyzing the free energy landscape with many local minima originated from the finite size. We find that the conventional theory predicts the contact angle at the global minimum if the droplet size is about 40 times or larger than the characteristic scale of the surface roughness, regardless of wetting modes. Furthermore, we obtain the energy barrier of pinning which can induce the contact angle hysteresis as a function of geometric factors. We validate our theory against experimental results on an anisotropic rough surface. In addition, we discuss the wetting on non-uniformly rough surfaces. Our findings clarify the extent to which the conventional wetting theory is valid and expand the physical understanding of wetting phenomena of small liquid drops on rough surfaces.
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Affiliation(s)
- Donggyu Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Nicola M. Pugno
- Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental, and Mechanical Engineering, University of Trento, Trento, Italy
- Center for Materials and Microsystems, Fondazione Bruno Kessler, Trento, Italy
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, United Kingdom
| | - Seunghwa Ryu
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
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84
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Wang T, Jiang L, Li X, Hu J, Wang Q, Ye S, Zhang H, Lu Y. Controllable anisotropic wetting characteristics on silicon patterned by slit-based spatial focusing of femtosecond laser. OPTICS EXPRESS 2016; 24:25732-25741. [PMID: 27828508 DOI: 10.1364/oe.24.025732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We propose a promising method to fabricate controllable anisotropic morphologies in which the slit-based spatial focusing of femtosecond laser is used to create an elliptical-shaped intensity distribution at focal plane, inducing elliptical-shaped morphology with micro/nano-dual-scale structures. Our study shows that 1) by increasing slit width, minor axis increases while major axis and axial ratio decrease; 2) with fixed slit width and laser fluence above the threshold, axial ratio is independent of irradiation pulse number; and 3) when polarization direction is changed from 0° to 90°, the axial ratio of anisotropic morphology declines. As a case study, large-area periodic anisotropic hierarchical structures are fabricated with the bidirectional anisotropic wetting.
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85
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Li C, Li N, Zhang X, Dong Z, Chen H, Jiang L. Uni-Directional Transportation on Peristome-Mimetic Surfaces for Completely Wetting Liquids. Angew Chem Int Ed Engl 2016; 55:14988-14992. [DOI: 10.1002/anie.201607514] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/07/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Chuxin Li
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
- School of Chemistry and Engineering; University of Chinese Academy of Sciences; Yuquan Road 100049 Beijing P.R. China
| | - Ning Li
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
- School of Chemistry and Engineering; University of Chinese Academy of Sciences; Yuquan Road 100049 Beijing P.R. China
| | - Xinshi Zhang
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
| | - Zhichao Dong
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
| | - Huawei Chen
- School of Mechanical Engineering and Automation; Beihang University; Beijing 100191 China
| | - Lei Jiang
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
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86
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Li C, Li N, Zhang X, Dong Z, Chen H, Jiang L. Uni-Directional Transportation on Peristome-Mimetic Surfaces for Completely Wetting Liquids. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201607514] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Chuxin Li
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
- School of Chemistry and Engineering; University of Chinese Academy of Sciences; Yuquan Road 100049 Beijing P.R. China
| | - Ning Li
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
- School of Chemistry and Engineering; University of Chinese Academy of Sciences; Yuquan Road 100049 Beijing P.R. China
| | - Xinshi Zhang
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
| | - Zhichao Dong
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
| | - Huawei Chen
- School of Mechanical Engineering and Automation; Beihang University; Beijing 100191 China
| | - Lei Jiang
- Key Laboratory of Bio-inspired Smart Interface Sciences; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Zhongguancun East Road, 29 100190 Beijing P.R. China
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87
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Takei A, Jin L, Fujita H, Takei A, Fujita H, Jin L. High-Aspect-Ratio Ridge Structures Induced by Plastic Deformation as a Novel Microfabrication Technique. ACS APPLIED MATERIALS & INTERFACES 2016; 8:24230-24237. [PMID: 27560778 DOI: 10.1021/acsami.6b07957] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Wrinkles on thin film/elastomer bilayer systems provide functional surfaces. The aspect ratio of these wrinkles is critical to their functionality. Much effort has been dedicated to creating high-aspect-ratio structures on the surface of bilayer systems. A highly prestretched elastomer attached to a thin film has recently been shown to form a high-aspect-ratio structure, called a ridge structure, due to a large strain induced in the elastomer. However, the prestretch requirements of the elastomer during thin film attachment are not compatible with conventional thin film deposition methods, such as spin coating, dip coating, and chemical vapor deposition (CVD). Thus, the fabrication method is complex, and ridge structure formation is limited to planar surfaces. This paper presents a new and simple method for constructing ridge structures on a nonplanar surface using a plastic thin film/elastomer bilayer system. A plastic thin film is attached to a stress-free elastomer, and the resulting bilayer system is highly stretched one- or two-dimensionally. Upon the release of the stretch load, the deformation of the elastomer is reversible, while the plastically deformed thin film stays elongated. The combination of the length mismatch and the large strain induced in the elastomer generates ridge structures. The morphology of the plastic thin film/elastomer bilayer system is experimentally studied by varying the physical parameters, and the functionality and the applicability to a nonplanar surface are demonstrated. Finally, we simulate the effect of plasticity on morphology. This study presents a new technique for generating microscale high-aspect-ratio structures and its potential for functional surfaces.
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Affiliation(s)
- Atsushi Takei
- Institute of Industrial Science, The University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Lihua Jin
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Civil & Environmental Engineering, Stanford University , Stanford, California 94305, United States
| | - Hiroyuki Fujita
- Institute of Industrial Science, The University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
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88
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Hiltl S, Böker A. Wetting Phenomena on (Gradient) Wrinkle Substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8882-8888. [PMID: 27517879 DOI: 10.1021/acs.langmuir.6b02364] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We characterize the wetting behavior of nanostructured wrinkle and gradient wrinkle substrates. Different contact angles on both sides of a water droplet after deposition on a gradient sample induce the self-propelled motion of the liquid toward smaller wrinkle dimensions. The droplet motion is self-limited by the contact angles balancing out. Because of the correlation between droplet motion and contact angles, we investigate the wetting behavior of wrinkle substrates with constant dimensions (wavelengths of 400-1200 nm). Contact angles of water droplets on those substrates increase with increasing dimensions of the underlying substrate. The results are independent of the two measurement directions, parallel and perpendicular to the longitudinal axis of the nanostructure. The presented findings may be considered for designing microfluidic or related devices and initiate ideas for the development of further wrinkle applications.
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Affiliation(s)
- Stephanie Hiltl
- Fraunhofer-Institut für Angewandte Polymerforschung IAP, D-14476 Potsdam-Golm, Germany
| | - Alexander Böker
- Fraunhofer-Institut für Angewandte Polymerforschung IAP, D-14476 Potsdam-Golm, Germany
- Lehrstuhl für Polymermaterialien und Polymertechnologien, Universität Potsdam , D-14476 Potsdam-Golm, Germany
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89
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López AB, de la Cal JC, Asua JM. Controlling film topography to form highly hydrophobic waterborne coatings. SOFT MATTER 2016; 12:7005-7011. [PMID: 27476531 DOI: 10.1039/c6sm01081d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Coatings have a tremendous impact on economy as they reduce corrosion that has an estimated cost of 3% of the world's GDP. Hydrophobic coatings are particularly efficient for this purpose and the challenge is to produce cost effective and environmentally friendly, highly hydrophobic, cohesive and non-porous coatings applicable to large and irregular surfaces. This work shows that this goal can be achieved by forming wrinkles on the surface of waterborne coatings through fine-tuning of the film forming conditions. The proof of concept was demonstrated by using waterborne dispersions of copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate and 2-ethylhexyl acrylate, and using the temperature and hardness of the copolymer as control variables during film formation. This allowed the formation of transparent films with a wrinkled surface that had a contact angle of 133°, which represents an increase of 20° with respect to the film cast under standard conditions.
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Affiliation(s)
- Ana B López
- POLYMAT and Kimika Aplikatua Saila, Kimika Zientzien Fakultatea, University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa, Tolosa Hiribidea 72, Donostia-San Sebastian, 20018, Spain.
| | - José C de la Cal
- POLYMAT and Kimika Aplikatua Saila, Kimika Zientzien Fakultatea, University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa, Tolosa Hiribidea 72, Donostia-San Sebastian, 20018, Spain.
| | - José M Asua
- POLYMAT and Kimika Aplikatua Saila, Kimika Zientzien Fakultatea, University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa, Tolosa Hiribidea 72, Donostia-San Sebastian, 20018, Spain.
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90
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Suzuki K, Ohzono T. Wrinkles on a textile-embedded elastomer surface with highly variable friction. SOFT MATTER 2016; 12:6176-6183. [PMID: 27338136 DOI: 10.1039/c6sm00728g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Wrinkling of a soft elastomer surface capped by a relatively hard thin film or modified by some physical treatments to induce hardening has been widely studied for applications in fields such as low-cost micro-fabrication, optics and tribology. Here we show that a biaxial textile sheet embedded on the surface of an elastomer buckles and selectively forms anisotropic wrinkles when experiencing a compressive strain in the fibre axial direction. The wrinkles also possess a fine surface structure that originates from the periodic structure of the biaxial textile sheet. Depending on whether the surface is wrinkled or not, the unique frictional property due to which the friction on wrinkles significantly decreases by a factor of less than 0.1 because of the localized contact regions on the protrusions originating from the textile structure is shown.
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Affiliation(s)
- K Suzuki
- Research Institute for Sustainable Chemistry, AIST, 1-1-1 Higashi, Tsukuba, 305-8565, Japan.
| | - T Ohzono
- Research Institute for Sustainable Chemistry, AIST, 1-1-1 Higashi, Tsukuba, 305-8565, Japan.
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91
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Chen D, McKinley GH, Cohen RE. Spontaneous wettability patterning via creasing instability. Proc Natl Acad Sci U S A 2016; 113:8087-92. [PMID: 27382170 PMCID: PMC4961185 DOI: 10.1073/pnas.1522700113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Surfaces with patterned wettability contrast are important in industrial applications such as heat transfer, water collection, and particle separation. Traditional methods of fabricating such surfaces rely on microfabrication technologies, which are only applicable to certain substrates and are difficult to scale up and implement on curved surfaces. By taking advantage of a mechanical instability on a polyurethane elastomer film, we show that wettability patterns on both flat and curved surfaces can be generated spontaneously via a simple dip coating process. Variations in dipping time, sample prestress, and chemical treatment enable independent control of domain size (from about 100 to 500 μm), morphology, and wettability contrast, respectively. We characterize the wettability contrast using local surface energy measurements via the sessile droplet technique and tensiometry.
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Affiliation(s)
- Dayong Chen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Gareth H McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Robert E Cohen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
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92
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Wang S, Yu N, Wang T, Ge P, Ye S, Xue P, Liu W, Shen H, Zhang J, Yang B. Morphology-Patterned Anisotropic Wetting Surface for Fluid Control and Gas-Liquid Separation in Microfluidics. ACS APPLIED MATERIALS & INTERFACES 2016; 8:13094-13103. [PMID: 27128986 DOI: 10.1021/acsami.6b01785] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This article shows morphology-patterned stripes as a new platform for directing flow guidance of the fluid in microfluidic devices. Anisotropic (even unidirectional) spreading behavior due to anisotropic wetting of the underlying surface is observed after integrating morphology-patterned stripes with a Y-shaped microchannel. The anisotropic wetting flow of the fluid is influenced by the applied pressure, dimensions of the patterns, including the period and depth of the structure, and size of the channels. Fluids with different surface tensions show different flowing anisotropy in our microdevice. Moreover, the morphology-patterned surfaces could be used as a microvalve, and gas-water separation in the microchannel was realized using the unidirectional flow of water. Therefore, benefiting from their good performance and simple fabrication process, morphology-patterned surfaces are good candidates to be applied in controlling the fluid behavior in microfluidics.
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Affiliation(s)
- Shuli Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Nianzuo Yu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Tieqiang Wang
- Research Center for Molecular Science and Engineering, Northeastern University , Shenyang 110004, P. R. China
| | - Peng Ge
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Shunsheng Ye
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Peihong Xue
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Wendong Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Huaizhong Shen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Junhu Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
| | - Bai Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, P. R. China
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93
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Shian S, Clarke DR. Electrically-tunable surface deformation of a soft elastomer. SOFT MATTER 2016; 12:3137-3141. [PMID: 26959839 DOI: 10.1039/c6sm00090h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The flat surface of a thin elastomer on a conducting substrate can be deformed by applying an electric field to a percolating network of metallic nanowires randomly dispersed over the surface. The magnitude of the field-induced surface undulations increases with the applied field and can locally be several times the diameter of the nanowires. Optical imaging indicates that the effect is reversible and the surface flatness is recovered when the electric field is removed. It is found that it is the field-induced changes in the surface morphology rather than the nanowires themselves that strongly scatter light. The optical effects could be exploited in functional devices including tunable privacy windows, displays, and camouflage. There is also the potential for tuning the adhesion of elastomers to other materials.
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Affiliation(s)
- Samuel Shian
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.
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94
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Jun I, Chung YW, Heo YH, Han HS, Park J, Jeong H, Lee H, Lee YB, Kim YC, Seok HK, Shin H, Jeon H. Creating Hierarchical Topographies on Fibrous Platforms Using Femtosecond Laser Ablation for Directing Myoblasts Behavior. ACS APPLIED MATERIALS & INTERFACES 2016; 8:3407-3417. [PMID: 26771693 DOI: 10.1021/acsami.5b11418] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Developing an artificial extracellular matrix that closely mimics the native tissue microenvironment is important for use as both a cell culture platform for controlling cell fate and an in vitro model system for investigating the role of the cellular microenvironment. Electrospinning, one of the methods for fabricating structures that mimic the native ECM, is a promising technique for creating fibrous platforms. It is well-known that align or randomly distributed electrospun fibers provide cellular contact guidance in a single pattern. However, native tissues have hierarchical structures, i.e., topographies on the micro- and nanoscales, rather than a single structure. Thus, we fabricated randomly distributed nanofibrous (720 ± 80 nm in diameter) platforms via a conventional electrospinning process, and then we generated microscale grooves using a femtosecond laser ablation process to develop engineered fibrous platforms with patterned hierarchical topographies. The engineered fibrous platforms can regulate cellular adhesive morphology, proliferation, and distinct distribution of focal adhesion proteins. Furthermore, confluent myoblasts cultured on the engineered fibrous platforms revealed that the direction of myotube assembly can be controlled. These results indicate that our engineered fibrous platforms may be useful tools in investigating the roles of nano- and microscale topographies in the communication between cells and ECM.
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Affiliation(s)
- Indong Jun
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
| | - Yong-Woo Chung
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
- Department of Mechanical Engineering, Korea University , Seoul 02841, Republic of Korea
| | - Yun-Hoe Heo
- Department of Bioengineering, Hanyang University , Seoul 04763, Republic of Korea
- BK21 Plus Future Biopharmaceutical Human Resources Training and Research Team , Seoul 133-791, Republic of Korea
| | - Hyung-Seop Han
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
| | - Jimin Park
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
| | - Hongsoo Jeong
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
- Department of Mechanical Engineering, Korea University , Seoul 02841, Republic of Korea
| | - Hyunjung Lee
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
| | - Yu Bin Lee
- Department of Bioengineering, Hanyang University , Seoul 04763, Republic of Korea
- BK21 Plus Future Biopharmaceutical Human Resources Training and Research Team , Seoul 133-791, Republic of Korea
| | - Yu-Chan Kim
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
- Korea University of Science and Technology , Daejeon 34113, Republic of Korea
| | - Hyun-Kwang Seok
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
- Korea University of Science and Technology , Daejeon 34113, Republic of Korea
| | - Heungsoo Shin
- Department of Bioengineering, Hanyang University , Seoul 04763, Republic of Korea
- BK21 Plus Future Biopharmaceutical Human Resources Training and Research Team , Seoul 133-791, Republic of Korea
| | - Hojeong Jeon
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science & Technology , Seoul 02792, Republic of Korea
- Korea University of Science and Technology , Daejeon 34113, Republic of Korea
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95
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Jokinen V. Directional imbibition on a chemically patterned silicon micropillar array. SOFT MATTER 2016; 12:1100-1106. [PMID: 26576647 DOI: 10.1039/c5sm01746g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Directional imbibition of oils (hexadecane, tetradecane, and dodecane) and water is demonstrated on a chemically patterned silicon micropillar array. Four different directional imbibition types are shown: unidirectional, two types of bidirectional and tridirectional imbibition. The surfaces consist of a silicon micropillar array with an overlaid surface chemistry pattern. This configuration leads to anisotropic wetting behaviour into various directions of the advancing meniscus. Due to the free energy landscape obtained, the advancing meniscus gets pinned in some directions (determined by the surface chemistry pattern) while it is free to move to the remaining directions. The conditions for directional imbibition and design criteria for the surfaces are derived and discussed.
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Affiliation(s)
- Ville Jokinen
- School of Chemical Technology, Aalto University, Micronova, Tietotie 3, 02150 Espoo, Finland.
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96
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Garg SK, Datta DP, Ghatak J, Thakur I, Khare K, Kanjilal D, Som T. Tunable wettability of Si through surface energy engineering by nanopatterning. RSC Adv 2016. [DOI: 10.1039/c6ra04906k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Schematic diagram of a water droplet on an isotropic (flat) and anisotropic (rippled) surfaces.
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Affiliation(s)
- S. K. Garg
- Institute of Physics
- Bhubaneswar 751 005
- India
- Inter-University Accelerator Centre
- New Delhi 110 067
| | - D. P. Datta
- Institute of Physics
- Bhubaneswar 751 005
- India
- School of Physical Sciences
- National Institute of Science Education and Research (NISER)
| | - J. Ghatak
- Department of Materials Science and Engineering
- National Cheng Kung University
- Tainan City 701
- Taiwan
- International Center for Materials Science
| | - I. Thakur
- Colloids and Materials Chemistry Department
- CSIR-Institute of Minerals and Materials Technology
- Bhubaneswar 751 013
- India
| | - K. Khare
- Department of Physics and Department of Mechanical Engineering
- Indian Institute of Technology Kanpur
- Kanpur 208 016
- India
| | - D. Kanjilal
- Inter-University Accelerator Centre
- New Delhi 110 067
- India
| | - T. Som
- Institute of Physics
- Bhubaneswar 751 005
- India
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97
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Luo Y, Song W, Wang X. Water repellent/wetting characteristics of various bio-inspired morphologies and fluid drag reduction testing research. Micron 2015; 82:9-16. [PMID: 26760225 DOI: 10.1016/j.micron.2015.12.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/17/2015] [Accepted: 12/17/2015] [Indexed: 10/22/2022]
Abstract
It is well-known that the bio-inspired sharkskin covering the original pattern has the apparent drag reduction function in the turbulent flowing stations, which can be regarded as "sharkskin effect", and it has progressively been put application into the fluid engineering with obtaining great profits. In this paper, the anisotropic wetting phenomena on sharkskin are discovered, the contact angles and rolling angles on different orientations are not the same. In addition, the hydrodynamic experiments on different sharkskin surfaces are conducted, and the experimental results illustrate that the super-hydrophobic and drag-reducing properties on deformed biological surfaces are improved to some extent compared to the original morphology, which has important significance to expand its practical applications.
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Affiliation(s)
- Yuehao Luo
- School of Engineering and Applied Science, The George Washington University, Washington D.C. 20052, USA.
| | - Wen Song
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi'an 710072, China
| | - Xudong Wang
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi'an 710072, China
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98
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Yong J, Chen F, Yang Q, Hou X. Femtosecond laser controlled wettability of solid surfaces. SOFT MATTER 2015; 11:8897-8906. [PMID: 26415826 DOI: 10.1039/c5sm02153g] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Femtosecond laser microfabrication is emerging as a hot tool for controlling the wettability of solid surfaces. This paper introduces four typical aspects of femtosecond laser induced special wettability: superhydrophobicity, underwater superoleophobicity, anisotropic wettability, and smart wettability. The static properties are characterized by the contact angle measurement, while the dynamic features are investigated by the sliding behavior of a liquid droplet. Using different materials and machining methods results in different rough microstructures, patterns, and even chemistry on the solid substrates. So, various beautiful wettabilities can be realized because wettability is mainly dependent on the surface topography and chemical composition. The distinctions of the underlying formation mechanism of these wettabilities are also described in detail.
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Affiliation(s)
- Jiale Yong
- Key Laboratory of Photonics Technology for Information of Shaanxi Province & State Key Laboratory for Manufacturing System Engineering, School of Electronics & Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Feng Chen
- Key Laboratory of Photonics Technology for Information of Shaanxi Province & State Key Laboratory for Manufacturing System Engineering, School of Electronics & Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Qing Yang
- Key Laboratory of Photonics Technology for Information of Shaanxi Province & State Key Laboratory for Manufacturing System Engineering, School of Electronics & Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Xun Hou
- Key Laboratory of Photonics Technology for Information of Shaanxi Province & State Key Laboratory for Manufacturing System Engineering, School of Electronics & Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
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99
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Chen CM, Chiang CL, Yang S. Programming Tilting Angles in Shape Memory Polymer Janus Pillar Arrays with Unidirectional Wetting against the Tilting Direction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:9523-9526. [PMID: 26305291 DOI: 10.1021/acs.langmuir.5b02622] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
By coating a thin layer of metal, including gold and gold-palladium alloy, of different thickness on the deformed shape memory polymer (SMP) pillars, we manipulate the degree of recovery of the SMP pillars. Pillars of different tilting angles were obtained as a result of balancing the strain recovery energy of the SMP pillars that favor the original straight state and the elastic energy of the metal layers that prefer the bent state. With this selective coating of a metal layer on the tilted pillars, we report a unique anisotropic liquid spreading behavior, where the water droplet is fully pinned in the direction of pillar tilting but advances in the reverse direction. This phenomenon is explained by the interplay of the surface chemistry and topography.
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Affiliation(s)
- Chi-Mon Chen
- Department of Materials Science and Engineering, University of Pennsylvania , 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Chang-Lung Chiang
- Department of Materials Science and Engineering, University of Pennsylvania , 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Shu Yang
- Department of Materials Science and Engineering, University of Pennsylvania , 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States
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100
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Tie L, Guo Z, Liu W. Anisotropic wetting properties on various shape of parallel grooved microstructure. J Colloid Interface Sci 2015; 453:142-150. [DOI: 10.1016/j.jcis.2015.04.066] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 04/29/2015] [Accepted: 04/29/2015] [Indexed: 11/25/2022]
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