1. Department of Materials Science & Engineering, Cornell University, Bard Hall, Ithaca, New York 14853
2. School of Biosciences, The University of Birmingham, Birmingham, B15 2TT, U.K.
3. Department of Materials, University of California at Santa Barbara, Santa Barbara, California 93106
4. KRATON Polymers, Houston, Texas 77082
5. National Institute of Standards and Technology, Gaithersburg, Maryland 20899