A High‐Refractive‐Index and Partially Chemically Recyclable Polymer From a Sulfur‐Rich Spiro ‐and‐Fused Tricyclic Monomer

The development of chemically recyclable polymers with high refractive indices is desirable for sustainable optics. Herein, a sulfur-rich spiro-tetrathioorthocarbonate motif was integrated into a fused bicyclic framework, yielding a spiro-and-fused tricyclic monomer, trans-tetrathiaspiro[4.5]decane-fused cyclooctene (M1). Its ring-opening metathesis polymerization (ROMP) produced polymer P1, which exhibits a high refractive index (n_D > 1.65), excellent thermal stability (T_d