1. National Institute of Standards and Technology, Gaithersburg, Maryland 20899, Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003, Department of Materials Science, SUNY at Stony Brook, Stony Brook, New York 11790, and Department of Chemical Engineering, University of Washington, Seattle, Washington 98195