Structure–Property Relationships in Multicyclic Polystyrenes: Synthesis, Physical Properties, and Comparison with Acyclic Counterparts

The syntheses of multicyclic polymers consisting of densely grafted cyclic chains have rarely been reported and their physical properties remain largely unexplored. In this study, multicyclic polystyrenes (mc-PS) with varying numbers of cyclic units were synthesized. The structure–property relationships were investigated, and to investigate the impact of the multicyclic topology, acyclic counterparts (i.e., graft polymers bearing linear PS side chains, g-PSs) were synthesized. The synthesized mc-PS demonstrated higher glass transition temperatures, enhanced thermal stabilities, reduced viscosities, and more compact hydrodynamic volumes than their acyclic counterparts. The mc-PS underwent a spherical-to-cylindrical structural transition upon increasing the number of cyclic units. The mc-PS possessed a slightly greater Kuhn length than the g-PS, indicating that the side-chain cyclic topology influenced the apparent rigidity of the norbornene backbone. These findings provide valuable insights into the relationships between molecular architectures and physical properties, opening new possibilities for the design of advanced materials.