Poly[n]catenanes, namely polymers comprised entirely of interlocked rings, have the potential to be an intriguing new class of materials. Specifically, the low energy requirements for the unusual motions (e.g. rotation, rocking) of the interlocked rings imparts a high degree of flexibility into the polymer backbone. It has been proposed this would lead to materials with unusual properties, such as good energy adsorption properties and low barrier to viscous flow. However, the confirmed synthesis of this interesting class of interlocked polymers has yet to be achieved. One key reason for this is the conflicting synthetic requirements for accessing macrocycles (dilute reactions conditions) and high molecular weight polymers (high reaction concentrations). Our synthetic approach to poly[n]catenanes aims at decoupling the polymerization and ring closing steps. To this end we have prepared metallo-supramolecular copolymers of a bis-ligand-containing macrocycle and a bis-ligand-containing olefin-end capped linear component, where metal/ligand coordination is the thermodynamic driving force for the polymerization process. The critical process in the poly[n]catenane synthesis is then the ring closing step of the linear component. We have been investigating the use of ring closing metathesis (RCM) to achieve this. The use of metal ion/ligand coordination with high binding constants, means it is possible to carry out the RCM under relatively dilute conditions, which minimizes crosslinking and maximizing ring closing, without a significant drop in molecular weight. Using this approach, we have been able to prepare a series of poly[n]catenanes and our latest results in this area will be discussed

Metallo-supramolecular polymers as a route to poly[n]catenanes

2019 Fall National Meeting

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