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

Abstract

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.