1. Institute of Polymer Research, GKSS-Forschungszentrum Geesthacht GmbH, Max-Planck-Str. 1, 21502 Geesthacht, Germany; A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Leninsky Prospekt 29, 119991 Moscow, Russia; SINTEF Materials and Chemistry, P.O. Box 124, Blindern, NO-0314 Oslo