Morphological studies of Cu(I)-complexed bipyridine-containing block copolymers by combined transmission electron microscopy techniques

Göldel, Andreas; Schubert, Ulrich S.; Eisenbach, Claus D.
The design of molecular species which can form well-defined macromolecular architectures by spontaneous, recognition-directed self-assembly of their components is a major goal in supramolecular chemistry. We synthesized block copolymers with polyether and bipyridine or oligo-(bipyridine) containing segments where the latter could form double-helical structures by metal complexation. Upon complexation with Cu(I) these systems showed a dramatic change in the thermal and mechanical properties from a waxy system to a thermoplastic elastomeric behaviour. This effect could be explained by the formation of a multiphase polymer system consisting of domains of bipyridine or oligo(bipyridine) Cu(I) complexes in a matrix of amorphous soft segments. In the solution-cast films both nitrogen and copper could be detected with electron energy-loss spectroscopy. Element spectroscopic imaging pictures of the net nitrogen and copper element distribution were identical and revealed a microphase-separated system with identical morphological structures. High-resolution bright-field images revealed fine structures (interference lines) which were in accordance with stacks of [Cu(I)(bpy)2] complexes. Electron diffraction patterns showed that the supramolecular order could be perfected through annealing.
Type of Publication:
Block copolymers; copper distribution; electron diffraction; electron energy loss spectroscopy EELS; element spectroscopic imaging ESI; microphase separation; nanoscopic structures oligo bipyridine Cu I complexes; supramolecular chemistry
Journal of Microscopy
67 - 74