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Design and creation of superwetting / antiwetting surfaces

Bionic technology Lab. Design and creation of superwetting / antiwetting surfaces. Xinjian Feng and Lei Jiang Advanced Materials Vol. 18, 3063–3078 (2006). KUAS Chemical Engineering. KUAS Chemical Engineering. 4. Superamphiphilic Surfaces. Outlook and Summary.

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Design and creation of superwetting / antiwetting surfaces

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  1. Bionic technology Lab Design and creation of superwetting /antiwettingsurfaces Xinjian Feng and Lei Jiang Advanced Materials Vol. 18, 3063–3078 (2006) KUAS Chemical Engineering

  2. KUAS Chemical Engineering 4 Superamphiphilic Surfaces Outlook and Summary Superhydrophobic Surfaces Surfaces with Reversible Superhydrophobicity and Superhydrophilicity 7 6 8 5 1 3 2 Surfaces with Superhydrophobicity and Superoleophilicity Fundamental Theories Introduction Bionic technology Lab Outline Superamphiphobic Surfaces

  3. KUAS Chemical Engineering Bionic technology Lab Abstract • Recent achievements in the construction of surfaces with special wettabilities,such as superhydrophobicity, superhydrophilicity, superoleophobicity,superoleophilicity, superamphiphilicity, superamphiphobicity,superhydrophobicity/superoleophilicity, and reversible switching between superhydrophobicity and superhydrophilicity, are presented. • Particular attention is paid to superhydrophobic surfaces created via various methods and surfaces with reversible superhydrophobicity and superhydrophilicity that are driven by various kinds of external stimuli.

  4. KUAS Chemical Engineering Bionic technology Lab Abstract • The control of the surface micro-/nanostructure and the chemical composition is critical for these special properties. • These surfaces with controllable wettability are of great importance for both fundamental research and practical applications.

  5. KUAS Chemical Engineering θ θ θ Bionic technology Lab Introduction- Wetting property 5˚<θ<90˚ Hydrophilic θ<5˚ Superhydrophilic θ>150˚ Superhydrophobic 90˚<θ <150˚ Hydrophobic Roughness substrate with hydrophilic material Smooth substrate with hydrophilic material Smooth substrate with hydrophobic material Roughness substrate with hydrophobic material

  6. KUAS Chemical Engineering Bionic technology Lab Introduction- superhydrophobic property in Nature 圖一、(A) water-strider legs(B) Iridescent peacock feathers(C) mosquito(D) lotus leaves KesongLiua and Lei Jianga,Nano Today 6, 155—175(2011)

  7. KUAS Chemical Engineering Bionic technology Lab Introduction- Lotus effect • Hierarchical structure • Low surface energy material 10μm wax 100nm http://nanotechweb.org/cws/article/tech/21936/1/0504031

  8. KUAS Chemical Engineering Bionic technology Lab Introduction • Artificial surfaces • Creating micro-/nanostructures on hydrophobic substrates • Chemically modifying a micro-/nanostructured surface with materials of low surface free energy

  9. KUAS Chemical Engineering Bionic technology Lab Introduction low surface free energy high surface free energy Figure 1. Illustration of the relationships between the four kinds of fundamental superwetting/antiwetting properties (in blue boxes) and the further special surface superwetting/antiwetting functions (in yellow boxes) that are obtained by combining either two of the fundamental properties. Herein, the double arrow indicates coexistence of the two properties, and the reversible arrow indicates switching of the two properties.

  10. KUAS Chemical Engineering Bionic technology Lab Fundamental Theories (液滴適用於平坦表面) • Young’s equation • γLV cosθ =γSV –γSL • (液滴適用於完全潤濕固體) • Wenzel’s equation • Cassie and Baxter equation (液滴適用於粗糙固體表面)

  11. KUAS Chemical Engineering Bionic technology Lab Artificial Superhydrophobic Surfaces • Template Synthesis • Phase Separation • Electrochemical Deposition (ECD) • Electrohydrodynamics (EDH) • Crystallization Control

  12. KUAS Chemical Engineering Bionic technology Lab Artificial Superhydrophobic Surfaces • Template Synthesis 膜板 基材 奈米轉印 脫膜 圖四、奈米轉印製備柱狀陣列 圖三、奈米轉印技術示意圖 袁 等人,軟模板法制備導電高分子微結構陣列,國高分子材料科學與工程研討會論文集, 2004 奈米轉印技術介紹 , 蔡宏營 博士

  13. KUAS Chemical Engineering Bionic technology Lab Artificial Superhydrophobic Surfaces • Phase Separation 圖五、 Ma et al., Electrospun Poly(Styrene-block-dimethylsiloxane) Block Copolymer Fibers Exhibiting Superhydrophobicity, Langmuir 2005, 21, 5549-5554

  14. KUAS Chemical Engineering Bionic technology Lab Artificial Superhydrophobic Surfaces • Electrochemical Deposition (ECD) Figure 6. SEM image of an aligned poly(alkylpyrrole) microtube film preparedvia the ECD method. The inset shows a water droplet on the film(scale bar: 500 lm). Reprinted from

  15. KUAS Chemical Engineering Bionic technology Lab Artificial Superhydrophobic Surfaces • Electrohydrodynamics (EDH) Figure 7. SEM images of superhydrophobic polystyrene films with special microsphere/nanofiber composite structures prepared via the EHDmethod. Reprinted from

  16. KUAS Chemical Engineering Bionic technology Lab Artificial Superhydrophobic Surfaces • Crystallization Control 圖六、 王 等人,超疏水网状结构对水中气泡的转移作用, 高等學校化學學報, 29, 12,2484, 2008

  17. KUAS Chemical Engineering Bionic technology Lab Multifunctional Superhydrophobic Surfaces • Increasing the surface roughness • decrease many other important properties • For practical industrial processes and our daily life. • Therefore, much attention has been devoted to the fabrication of multifunctional superhydrophobic films.

  18. KUAS Chemical Engineering Bionic technology Lab Multifunctional Superhydrophobic Surfaces • Superhydrophobic Surfaces with Optical Properties 圖七、透明超疏水薄膜

  19. KUAS Chemical Engineering Bionic technology Lab Multifunctional Superhydrophobic Surfaces • Superhydrophobic Surfaces with Highly Adhesive Forces Figure 8. Superhydrophobic aligned PS nanotube films with high adhesive force. Shapes of the water droplets on the as-prepared PS nanotube films at tilt angles of a) 0° and b) 180°. c) SEM top image of the as-prepared aligned PS nanotubes films. Reprinted from

  20. KUAS Chemical Engineering Bionic technology Lab Multifunctional Superhydrophobic Surfaces • Superhydrophobic Surfaces with High Electrical Conductivity Figure 9. SuperhydrophobicZnOnanoporous films with good conductivity.a) Atomic force microscopy 3D image of the as-prepared thin films.b) Simultaneous current scanning image of the as-prepared film at a biasvoltage of 0.5 V. Reprinted with permission from

  21. KUAS Chemical Engineering Bionic technology Lab Multifunctional Superhydrophobic Surfaces • Anisotropic Superhydrophobic Surfaces 圖八、Contact angle, sliding angle

  22. KUAS Chemical Engineering Bionic technology Lab Multifunctional Superhydrophobic Surfaces • Superhydrophobic Surfaces over the Entire pH Range Figure 10. The relationship between pH values and contact angles onnanostructuredgraphitelike carbon films. The high contact angle of theacid, water, and alkali on the film indicates that the as-prepared film issuperhydrophobic over the entire pH range.

  23. KUAS Chemical Engineering Bionic technology Lab Surfaces with Superhydrophobicity and Superoleophilicity Figure 11. PTFE-coated copper mesh and its extreme wettability response for oil/water. The as-prepared films show superhydrophobicity, while, when a diesel oil droplet contacts it, the oil spreads quickly on the film and permeates through the film within 240 ms, showing good superoleophilicity

  24. KUAS Chemical Engineering Bionic technology Lab Surfaces with Reversible Superhydrophobicityand Superhydrophilicity Figure 12. Relationship between the water CA and the chain length of nalkanoic acids on dual-scale rough copper films that are prepared via electrodeposition. The insets show the shapes of the water droplets on films modified with n-propanoic acid (left) and n-octanoic acid (right).

  25. KUAS Chemical Engineering Bionic technology Lab Surfaces with Reversible Superhydrophobicityand Superhydrophilicity • Light Irradiation Figure 13. Reversible switching between superhydrophobicity and superhydrophilicity of inorganic nanorod films. a) Field-emission SEM top image of the as-prepared ZnOnanorod film. b) Lotuslike TiO2 nanorod film. Reprinted with permission from. c) Changes in the water-droplet shape on aligned ZnOnanorod films before (left) and after (right) UV illumination. Reprinted with permission from .

  26. KUAS Chemical Engineering Bionic technology Lab Surfaces with Reversible Superhydrophobicityand Superhydrophilicity • Thermal Response Figure 14. a) Schematic diagram of the reversible competition between inter- and intramolecular hydrogen bonding, which is the molecular mechanism of the temperature-responsive switching on a PNIPAAm film. b) Water-drop profile for thermally responsive switching between superhydrophobicity and superhydrophilicity of PNIPAAm-modified micro-and nanostructured Si surfaces at 25 °C (left) and 40 °C (right), respectively.

  27. KUAS Chemical Engineering Bionic technology Lab Surfaces with Reversible Superhydrophobicityand Superhydrophilicity • Solvent Effect • When mixed polymer contain incompatible hydrophobic and hydrophilic components are attached to a substrate. • Y-shaped molecule composed of hydrophobic polystyrene and hydrophilic poly(acrylic acid) (PAA) chains was designed and grafted to a silicon surface. • After the film was treated with toluene, a good solvent for PS, the top surface layer was enriched with PS arms,whereasthe PAA arms collapsed into cores

  28. KUAS Chemical Engineering Bionic technology Lab Surfaces with Reversible Superhydrophobicityand Superhydrophilicity • Electric-Field Response 圖九、電潤濕原理 http://www.materialsnet.com.tw/DocView.aspx?id=7284

  29. KUAS Chemical Engineering Bionic technology Lab Surfaces with Reversible Superhydrophobicityand Superhydrophilicity • Mechanical Force Induction • When PTFE was extended axially with anextension ratio change from 0 to 190 %, the water CA increasedfrom 108° to 165°. • The reason for thischange in wettability is due to the change of the density of thePTFE crystals during the axial extension.

  30. KUAS Chemical Engineering Bionic technology Lab Outlook and Summary • superhydrophobicity or superhydrophilicity • requires a rough surface structure. • Smart devices • surface wettability can be reversibly switched. • Future work • improve the mechanical stability of functional rough surfaces. • design new multifunctional materials. • intelligent materials can be tuned by dual or multiple external stimuli

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