Generation of Hierarchical Topologies from Photocrosslinkable, Particle-Stabilized Emulsions a Jason J. Benkoski,* Hua Hu, Alamgir Karim National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA E-mail: jason.benkoski@nist.gov Received: April 19, 2006; Revised: June 1, 2006; Accepted: June 6, 2006; DOI: 10.1002/marc.200600272 Keywords: biomimetic; colloids; crosslinking; interfaces; microstructure; photopolymerization; self-assembly Introduction Surface properties often play a central role in the design of advanced materials for demanding applications. Although the design goals may often be met through surface chemistry, recent discoveries suggest that greater gains may be made through control of topology. Nowhere can this better be seen than in nature. The microscopic structure of shark skin has been shown to play a critical role in reducing frictional drag. [1,2] One may also look to the iridescent patterns on butterfly wings, which result not from pigmentation, but from the interference and diffraction of light from the nano- structured ridges on their surfaces. [3] As seen above, different length scales are optimal for different applications. In many cases the size scale is set by tradeoffs between competing properties. When tradeoffs occur, nature overcomes this limitation by creating a hier- archy of surface structures over multiple length scales. Such hierarchically rough surfaces are responsible for both the superhydrophobicity of lotus leaves [4–7] and the unmatched adhesive properties of gecko feet. [8–10] When properly applied, this strategy makes it possible to optimize the desired properties while minimizing any unwanted side effects. The main lesson to be learnt from nature is that extra- ordinary properties can be achieved with ordinary materials. Observe that none of the starting materials are particularly exotic (e.g., keratin, wax, chitin). Instead, we see that the choice of material appears to depend less on properties than on availability. In this respect, nature makes a strong case for Summary: We describe a way to obtain biomimetic, hier- archical surface morphologies. In order to mimic natural sur- faces more accurately such as lotus leaves and gecko feet, we employ a strategy that bears many of the attractive character- istics of natural materials synthesis. The system in question consists of a photocurable monomer and water. To this quasi- two-component system we add polymer latex spheres. The monomer–water interface is then manipulated according to the well-established science of complex fluids. Drawing from the rich phase behavior of particle-stabilized emulsions, we demonstrate the creation of complex biomimetic morphologies over many length scales. The resulting structures are then solidified by crosslinking the monomer with UV light. Comparison of an AFM image of a PMMA colloidosome assembly with that of the textured surface of a superhydro- phobic Hygoryza aristata leaf (inset). Macromol. Rapid Commun. 2006, 27, 1212–1216 ß 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1212 DOI: 10.1002/marc.200600272 Communication a Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States.