1. Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602; Department of Chemical & Environmental Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260; Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; and Material Science Laboratory, Mitsui Chemicals, Inc., 580-32 Nagaura Sodegaura-City, Chiba 299-0265, Japan