Curvature‐Driven Reversible In Situ Switching Between Pinned and Roll‐Down Superhydrophobic States for Water Droplet Transportation

Artifi cial superhydrophobic surfaces [ 1–10 ] with water contact angles (CAs) greater than 150 ° have been intensively investigated due to their unique “anti-water” property that could be utilized in a wide range of applications. [ 11–13 ] Recent development of intelligent devices, such as microfl uidic switches and biomedicine transporters, makes strong demands on surface wettability control, therefore, responsive surfaces have become a signifi cant issue for superhydrophobic studies. Up to now, various smart surfaces have been successfully developed as reversible switches for wettability control through a micronanostructured surface on a responsive material. [ 14–25 ] These unique tunings of surface wettability greatly contributed to refi ned control of surface wettability. With the thorough understanding of superhydrophobic phenomenon, superhydrophobic surfaces have been classifi ed into fi ve states [ 26 ] according to the details of CA hysteresis, which have been well verifi ed on different samples based on experimental results. [ 1 , 8 , 27–29 ]

[1]  P. Gould.  Smart, clean surfaces , 2003 .

[2]  A. Athanassiou,et al.  Reversibly Light‐Switchable Wettability of Hybrid Organic/Inorganic Surfaces With Dual Micro‐/Nanoscale Roughness , 2009 .

[3]  Ichimura,et al.  Light-driven motion of liquids on a photoresponsive surface , 2000, Science.

[4]  Chao Li,et al.  Reversible Switching of Water‐Droplet Mobility on a Superhydrophobic Surface Based on a Phase Transition of a Side‐Chain Liquid‐Crystal Polymer , 2009, Advanced Materials.

[5]  D. Beebe,et al.  Surface-directed liquid flow inside microchannels. , 2001, Science.

[6]  Insung S. Choi,et al.  Fabrication of Hairy Polymeric Films Inspired by Geckos: Wetting and High Adhesion Properties , 2008 .

[7]  Vasan Venugopalan,et al.  Examination of laser microbeam cell lysis in a PDMS microfluidic channel using time-resolved imaging. , 2008, Lab on a chip.

[8]  F. Shi,et al.  Reversible pH‐Responsive Surface: From Superhydrophobicity to Superhydrophilicity , 2005 .

[9]  Yanlin Song,et al.  Photo-switched wettability on an electrostatic self-assembly azobenzene monolayer. , 2005, Chemical communications.

[10]  Dong Yun Lee,et al.  Superhydrophobic to Superhydrophilic Wetting Transition with Programmable Ion‐Pairing Interaction , 2008 .

[11]  S. Shoji,et al.  Three‐Dimensional Nanonetwork Assembled in a Photopolymerized Rod Array , 2003 .

[12]  David G. Evans,et al.  Corrosion resistance of superhydrophobic layered double hydroxide films on aluminum. , 2008, Angewandte Chemie.

[13]  Xia Hong,et al.  Application of superhydrophobic surface with high adhesive force in no lost transport of superparamagnetic microdroplet. , 2007, Journal of the American Chemical Society.

[14]  Peng Jiang,et al.  Bioinspired Self‐Cleaning Antireflection Coatings , 2008 .

[15]  Zhiguang Guo,et al.  Stable Bionic Superhydrophobic Coating Surface Fabricated by a Conventional Curing Process , 2008 .

[16]  S. Pispas,et al.  Smart Polymer Surfaces , 2003 .

[17]  Akira Fujishima,et al.  Structural color and the lotus effect. , 2003, Angewandte Chemie.

[18]  P. C. Rieke,et al.  Reversible Surface Properties of Glass Plate and Capillary Tube Grafted by Photopolymerization of N-Isopropylacrylamide , 1998 .

[19]  Bharat Bhushan,et al.  Biologically Inspired Surfaces: Broadening the Scope of Roughness** , 2008 .

[20]  Mao,et al.  Raman spectroscopy of iron to 152 gigapascals: implications for Earth's inner core , 2000, Science.

[21]  Lei Jiang,et al.  Definition of Superhydrophobic States , 2007 .

[22]  Chunxiong Luo,et al.  Artificial lotus leaf by nanocasting. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[23]  R. N. Wenzel.  RESISTANCE OF SOLID SURFACES TO WETTING BY WATER , 1936 .

[24]  Hong-Bo Sun,et al.  One-step preparation of regular micropearl arrays for two-direction controllable anisotropic wetting. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[25]  Robert Vajtai,et al.  Ultrathick Freestanding Aligned Carbon Nanotube Films , 2007 .

[26]  Lichao Gao,et al.  The "lotus effect" explained: two reasons why two length scales of topography are important. , 2006, Langmuir : the ACS journal of surfaces and colloids.

[27]  Hong-Bo Sun,et al.  A simple strategy to realize biomimetic surfaces with controlled anisotropic wetting , 2010 .

[28]  F. Caruso,et al.  Tunable Superhydrophobic and Optical Properties of Colloidal Films Coated with Block‐Copolymer‐Micelles/Micelle‐Multilayers , 2007 .

[29]  Hong Xia,et al.  A facile approach for artificial biomimetic surfaces with both superhydrophobicity and iridescence , 2010 .

[30]  Jin Zhai,et al.  Reversible super-hydrophobicity to super-hydrophilicity transition of aligned ZnO nanorod films. , 2004, Journal of the American Chemical Society.

[31]  Wook Park,et al.  Three-dimensional fabrication of heterogeneous microstructures using soft membrane deformation and optofluidic maskless lithography. , 2009, Lab on a chip.

[32]  Wilfred Chen,et al.  Reversible conversion of conducting polymer films from superhydrophobic to superhydrophilic. , 2005, Angewandte Chemie.

[33]  S. Kulkarni,et al.  Electric field induced, superhydrophobic to superhydrophilic switching in multiwalled carbon nanotube papers. , 2008, Nano letters.

[34]  Lei Jiang,et al.  Designing Superhydrophobic Porous Nanostructures with Tunable Water Adhesion , 2009 .

[35]  Eduard Arzt,et al.  Hierarchical Gecko‐Like Adhesives , 2009 .

[36]  Hong Xia,et al.  Self-organization of polymer nanoneedles into large-area ordered flowerlike arrays , 2009 .

[37]  L. Jiang,et al.  Multiresponsive Surfaces Change Between Superhydrophilicity and Superhydrophobicity , 2007 .

[38]  Yong‐Lai Zhang,et al.  Superhydrophobic nanoporous polymers as efficient adsorbents for organic compounds , 2009 .

[39]  A. Cassie,et al.  Wettability of porous surfaces , 1944 .

[40]  J. Lahann,et al.  A Reversibly Switching Surface , 2003, Science.

[41]  Lei Zhai,et al.  Stable Superhydrophobic Coatings from Polyelectrolyte Multilayers , 2004 .

[42]  S. Bell,et al.  Sheets of large superhydrophobic metal particles self assembled on water by the Cheerios effect. , 2008, Angewandte Chemie.

[43]  S. Franssila,et al.  Complex Droplets on Chemically Modified Silicon Nanograss , 2008 .

[44]  Rabah Boukherroub,et al.  Reversible electrowetting on superhydrophobic silicon nanowires. , 2007, Nano letters.