1. Department
of Chemical Engineering-Product Technology, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG, The Netherlands
2. Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
3. Electron Microscopy-Groningen Biomolecular Sciences and Biotechnology Institute, Rijksuniversiteit Groningen, Nijeborgh 7, 9747 AG, The Netherlands