1. Fiber and Polymer Science Program, Campus Box 8301, North Carolina State University, Raleigh, North Carolina 27695-8301; Center for High Performance Manufacturing, College of Engineering, Virginia Polytechnic Institute & State University, 132 Norris Hall, Blacksburg, Virginia 24061-0219; and Department of Chemistry, Campus Box 8204, North Carolina State University, Raleigh, North Carolina 27695-7907