1. Contribution from the The Petroleum and Petrochemical College, Chulalongkorn University, Soi Chula 12, Phyathai, Bangkok 10330, Thailand, Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202, and Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan