Mind & Matter

 

Shape-Shifting Plastic

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Duke engineers Qiming Wang and Xuanhe Zhao demonstrate real-time texture modification in plastic. Photo: Pratt School of Engineering, Duke University

 

One benefit of failure is that it can inform unanticipated future technological pursuits. In the case of plastic insulators, for example, Duke University engineer Xuanhe Zhao used to study the ways in that the plastic sheathing used to protect wire cables fails over time due to the presence of electrical current. Zhao noted that higher voltages caused the material to deteriorate, with visible perforations and creases forming on its surface.

Based on this discovery, Zhao formulated a new set of experiments focused on the interplay between electricity and polymer surface effects. The result of this research is an ability to modify the surface characteristics of plastics on demand. “By changing the voltage applied to the polymer, we can alter the surface from bumpy to smooth and back again,” reports Zhao. “There are many instances, for example, when you’d want to be able to change at will a surface from one that is rough to slippery and back again.”

Unlike permanently etched plastic, the surface of which is shaped by technologies like electrostatic lithography, Zhao's technology is not fixed. He demonstrates the ability to produce a variety of shapes based on the application of specific voltages. Moreover, the changes occur within milliseconds, offering precise control over the material surface. “The changeable patterns we have created in the laboratory include circles and straight and curved lines, which are basic elements of fingerprints,” said Zhao, who cites protective gloves as one potential application, stating that the "technology can produce gloves with on-demand textures and smoothness tuned for various applications, such as climbing and gripping. Furthermore, surfaces capable of dynamically changing patterns are also useful for many technologies, such as microfluidics and camouflage.”

Architectural applications could include selective self-cleaning and hydrophobic materials—especially surfaces that are required to have texture much of the time, such as flooring. A questions remains, however, concerning the lifespan of Zhao's plastics, particularly if material failure was the impetus for this important discovery.

 

 
 

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About the Blogger

Blaine Brownell

thumbnail image Minnesota-based architect and author Blaine Brownell, AIA, is a self-defined materials researcher and sustainable building adviser. His "Product of the Week" emails and three volumes of Transmaterial (2006, 2008, 2010) provide designers with a steady flow of inspiration—a 21st-century Grammar of Ornament. Blaine has practiced architecture in Japan and the U.S. and has been published in more than 40 design, business, and science publications. The recipient of a Fulbright fellowship for 2006–07, he researched contemporary Japanese material innovations at the Tokyo University of Science. He currently teaches architecture and co-directs the M.S. in Sustainable Design program at the University of Minnesota. His book Matter in the Floating World was published by Princeton Architectural Press in 2011.