Advances in High Refractive Index Cycloolefin-Containing Polymeric Materials

High-refractive-index polymers (HRIPs) are critical materials for advanced optoelectronic devices and have long been sought after. Importantly, cycloolefin-containing polymers have emerged as promising candidates due to their exceptional optical properties and broad range of applications; however, accessing HRIPs based on cycloolefin architectures remains a considerable challenge. To synthesize HRIPs, aromatic rings, sulfur atoms, and halogens (except fluorine) are commonly employed. This perspective highlights recent advances in the design and synthesis of high-refractive-index cycloolefin-containing polymeric materials through various synthetic methods, including coordination polymerization, ring-opening metathesis polymerization, thiol–ene click reaction, inverse vulcanization, and nanohybridization with inorganic additives. It also gives an outlook on promising directions in developing novel HRIPs based on cycloolefin frameworks for versatile applications.