Self-assembled poly[2]catenanes based on non-covalent and dynamic covalent bonds

Abstract

As the typical type of mechanically interlocked polymers (MIPs), polycatenanes (PCs) have attracted wide attention because they show several modes of motion. Developing a novel methodology to prepare PCs that has the potential to be scalable is significant. Currently, a kinetically controlled reaction is indispensable for various types of PCs, which remains the main restriction for currently reported PCs to be scalable. In contrast, herein, we report self-assembled poly[2]catenanes stemming from non-covalent and dynamic covalent bonds. M1 featuring two unclosed rings linked via an alkyl chain was prepared, and supramolecular polymers (SPs) were generated through the self-assembly of M1 resulting from intramolecular hydrogen bonding and π–π interactions. Upon the addition of 2,6-pyridinedicarbaldehyde M2, a dynamic covalent self-assembly process occurred between M2 and the SPs. The incorporated aldehyde groups of M2 could spontaneously react with the amino groups of M1 to generate imine bonds, resulting in the occurrence of ring-closing to transform SPs into linear poly[2]catenanes. This work succeeded in preparing poly[2]catenanes totally by a self-assembly approach rather than using a kinetically controlled reaction, offering a new strategy for synthesizing MIPs.