Introduction of Triptycene with a Particular Substitution Pattern into Polymer Chains Can Dramatically Improve the Structural and Rheological Properties.

Although a large number of polymers that contain triptycene units in the main chains have been developed, no polymer design using 1,8-substituted triptycene has been reported to date. In this study, we investigated the properties of linear homo- and copolymers obtained by ring-opening polymerization of a triptycene monomer bearing a macrocyclic olefin linked at its 1,8-position and its copolymerization with cyclooctene, respectively. We found that the introduction of triptycene with this substitution pattern leads to nanoscale molecular ordering, thereby greatly improving the physical properties of the polymers. The key to this remarkable behavior of 1,8-substituted triptycene-containing polymers is the formation of a particular two-dimensional assembly of the triptycene units by nested hexagonal packing, which aligns one-dimensionally while folding the polymer chains into a well-defined layered structure. The polymer design using 1,8-substituted triptycene can be applied to other polymers, unless their main chain contains functional groups capable of a strong intermolecular interaction such as hydrogen bonding.