1. Department of Engineering Physics and Mathematics, Materials Physics Laboratory, Helsinki University of Technology, P.O. Box 2200, FIN-02015 HUT, Espoo, Finland; Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow 117912, Russia; Department of Chemistry, Purdue University, West-Lafayette, Indiana 47907; and Department of Polymer Science and Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands