1. United States Army Research Office, 4300 So. Miami Blvd., P.O. Box 12211, Research Triangle Park, North Carolina 27709-2211, Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Ueda 386, Japan, and Department of Chemistry and Biochemistry and Center for Polymer Research, The University of Texas at Austin, Austin, Texas 78712