NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This study was supported by Grant No. DMR-0446470 between the National Academy of Sciences and the National Science Foundation. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project.

Cover: An electric field can cause a polymer film to be unstable. If, in addition, the polymer does not stick to the surface of the underlying support, the polymer will withdraw from the surface, like water on a nonstick pan. These two factors produce an instability that can be seen with an optical microscope by the interference colors. The instability, in this case, has caused the formation of this unusual structure, since the electric field that was used was not uniform across the film. The fingerlike texture can be used to measure the properties of the polymer. Courtesy of T. Xu, University of Massachusetts at Amherst.