A simple strategy to realize biomimetic surfaces with controlled anisotropic wetting

State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, People's Republic of China
Applied Physics Letters (Impact Factor: 3.79). 03/2010; DOI: 10.1063/1.3297881
Source: IEEE Xplore

ABSTRACT The study of anisotropic wetting has become one of the most important research areas in biomimicry. However, realization of controlled anisotropic surfaces remains challenging. Here we investigated anisotropic wetting on grooves with different linewidth, period, and height fabricated by laser interference lithography and found that the anisotropy strongly depended on the height. The anisotropy significantly increased from 9° to 48° when the height was changed from 100 nm to 1.3 μ m . This was interpreted by a thermodynamic model as a consequence of the increase of free energy barriers versus the height increase. According to the relationship, controlled anisotropic surfaces were rapidly realized by adjusting the grooves’ height that was simply accomplished by changing the resin thickness. Finally, the perpendicular contact angle was further enhanced to 131°±2° by surface modification, which was very close to 135°±3° of a common grass leaf.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate directional electromechanical properties of poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDOT/PSS) composite films containing aligned poly(vinyl pyrrolidone)/poly(methyl methacrylate) nanofiber assemblies. The aligned nanofiber assemblies showed anisotropic wettability based on the high alignment degree of the nanofibers. The PEDOT/PSS composite film containing aligned nanofibers displayed an anisotropic actuation response when a voltage was applied in air. The orientation of the embedded nanofibers within the PEDOT/PSS matrix leads to the control of actuation direction because of the difference of anisotropic mechanical properties in the composite films.Keywords: anisotropic actuation; conductive polymer; electrospinning; mechanical properties; wetting
    Polymer Journal 07/2011; 43(10):849-854. · 1.50 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Holographic lithography is a convenient, inexpensive technique to fabricate large-area, periodic biofunctional templates such as antireflection and superhydrophobic surfaces. As opposed to two-beam interference (TBI), which produces grating patterns, interference of three or more beams can create multifarious patterns of symmetry, which have broader range of functions. However, as the number of beams used increases, the configuration gets more complicated, and thus possibly incurs more errors of alignment. To avoid the issue, we employed the technique of multi-exposure of two-beam interference to fabricate two-dimensional periodic structures and quasi-periodic structures. The theoretical simulation of 2n-beam interference (n is a positive integer) and n exposures of TBI was compared to validate that patterns made by 2n-beam interference could also be made by n exposures of TBI. Structures with symmetry of different folds were demonstrated not only on the negative photoresist SU-8 based on an add-type fabrication approach but also directly on the surface of the infrared window material zinc sulfide (ZnS) through a subtract-type fabrication approach. A transmittance of more than 90% and a water contact angle of 145° were obtained by three exposures of two-beam interference, and a transmittance of 80% as well as a water contact angle of 126° by ablation of nine exposures of TBI on ZnS substrate.
    Journal of Lightwave Technology 01/2013; 31(2):276-281. · 2.56 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: It has been shown before that anisotropically microstructured surfaces exhibit anisotropic wetting phenomena. This study presents a possibility to control the anisotropy of wetting by tailoring the surface chemistry. PDMS microchannels were permanently hydrophilized and subsequently functionalized further. Thereby, systematic studies on the effect of the surface modification on the wetting properties of microstructures have been possible. Importantly, we found that the wetting parallel to the groove strongly depended on the chemical modification of the structure although the wetting perpendicular to the groove is almost unaffected. Through immobilization of a monolayer of Si nanoparticles (SiNPs) exclusively on the elevations of the hydrogel-coated microstructured PDMS substrate, the anisotropic wetting could be selectively altered unidirectionally along the pattern direction.
    Langmuir 09/2013; · 4.38 Impact Factor

Full-text (2 Sources)

Available from