1. Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan, Wood Research Institute, Kyoto University, Uji-shi, Kyoto, 611, Japan, and Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan