1. Contribution from the Laboratory for Macromolecular and Organic Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands, National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, Laboratory of Polymer Technology, Eindhoven University of Technology, Eindhoven, The Netherlands, and Soft Matter CryoTEM Research Unit, Eindhoven University of Technology, Eindhoven, The Netherlands