1. Laboratory of Polymer Chemistry, University of Helsinki, PB 55, FIN-00014 HY, Finland, KSV Instruments Ltd., Höyläämötie, FIN-00380 Helsinki, Finland, VTT Processes, Materials and Chemicals, PB 1602, FIN-02044 VTT, Finland, and Department of Physical Chemistry, Åbo Akademi University, Porthansgatan 3−5 SF-20500 Turku, Finland