1. Department of Macromolecular Science, Faculty of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
2. School of Chemical and Biological Engineering Seoul National University, Seoul 151-744, South Korea
3. Department of Polymer Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
4. Department of Chemical Engineering, University of Houston, Houston, Texas 77204-4004