1. Center for Advanced Functional Polymers, Department of Chemistry and School of Molecular Science (BK21), Korea Advanced Institute of Science and Technology, 373-1, Kusung-Dong, Yusung-Gu, Taejon 305-701, Korea, and Departments of Chemical Engineering and Chemistry, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea