Rational design and efficient synthesis of cyclic polymers with visualized molecular topology and unique dielectric properties

Cyclic polymers without chain ends have attracted increasing attention because of the unique physical properties. However, the direct visualization of cyclic topology remains a formidable challenge, because the cyclic chains with flexible backbone or strong intramolecular interaction usually existed in a coiled state rather than cyclic topology. Herein, monocyclic and bicyclic polymers were prepared via blocking-cyclization technique, and the molecular topology of cyclic polymer containing phenyl pendant was directly observed depending on the reduced intrachain entanglement. The structure and characteristics of cyclic polymers were investigated, and the difference between cyclic polymer and linear counterpart was demonstrated. Compared to linear polymer, cyclic polymer exhibited improved dielectric properties, and bicyclic polymer displayed further increased dielectric constant and energy storage density than monocyclic polymer possessing the same repeating units. Therefore, this research presents a facile strategy in the design and construction of cyclic polymers with directly visualized topology and unique dielectric properties.