Formation of Wrinkle Patterns on Porous Elastomeric Membrane and Their fabrication of Hierarchical Architectures
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1129-V04-07
Formation of Wrinkle Patterns on Porous Elastomeric Membrane and Their fabrication of Hierarchical Architectures
Yue Cui and Shu Yang Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104
ABSTRACT We report the formation of wrinkle patterns on porous elastomeric membrane and their fabrication of hierarchical architectures through mechanical stretching and replica molding. The technique builds upon a buckling instability of a stiff layer supported by a porous elastomeric membrane which was induced by surface plasma oxidation of the pre-stretched porous elastomer followed by removal of the applied mechanical strain to form wrinkle patterns, and replica molding of the deformed features on the porous membrane into epoxy to form hierarchical architectures through casting the UV-curable epoxy prepolymer and UV curing. We find that due to the existence of micropores on the membrane, the formation of wrinkle patterns is different from that formed on a continuous elastomeric film, and by varying the applied mechanical stretching strain condition and plasma oxidation condition, the wrinkle patterns could be either confined by the micropores on the membrane to exhibit a wavelength equal to its pitch or form wrinkles with much large wavelength compared with that formed on a continuous elastomeric film. Therefore, the micropillar arrays fabricated by replica molding could stand on different types of wrinkle patterns to form different hierarchical architectures. The method we illustrate here offers a simple and cost-effective approach to fabricate various hierarchical structures, and provides possibilities for potential applications in various fields, such as microfluidics, microand nanofabrication of complex structures, crystal formation, cell attachment, superhydrophobicity and dry adhesion.
INTRODUCTION It is well known that surface properties, such as hydrophobicity and adhesion, can be manipulated by both physical roughness (topography) and chemical heterogeneity. Nature offers excellent examples of hierarchical architecture with multi-faceted functions. Superhydrophocity found in aquatic plants, notably Lotus leaves, 2,3 and insect wings 4, and adhesion found in gecko’s toe pads 5, 6 have been attributed to their micro- and nano-rough hierarchical architectures. Inspired by the bioorganisms, the control of interfacial properties have been affecting to human’s daily life and scientific research. By mimic Nature, many researchers have studied wettability, adhesion, friction, biocompatibility, and etc and applied them for surface coating to make the surface to be protective, self-cleaning, fouling-releasing, antifogging, antistatic, antifriction, etc.
Patterning of soft materials provides an exceptional route for the generation of nano- to micro- scale hierarchical structures. Non-photolithographic methods have attracted great attentions not only due to their simplicity, low cost, versatility, and surface three-dimensionality. 7 Fabrication of nano-/micro- structu
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