Chemically Recyclable Poly(tetrathioorthocarbonate)s: Combining High Refractive Index and Abbe Number

Polymers with high refractive index (n) and Abbe number (v_D) have the potential to be used in advanced optical devices. However, fabricating such materials is challenging because of the inherent trade-off between light refraction and dispersion. Herein, we present an efficient strategy for synthesizing sulfur-rich polymers with tetrathioorthocarbonate as the functional group through the alternating copolymerization of thiiranes and cyclic trithiocarbonates in a controlled fashion. Notably, the tetrathioorthocarbonates with features of high sulfur content, cyclic structure, and free C═S bonds afforded excellent optical properties with an n under 589.3 nm of 1.706, v_D of 40.9, and optical transparency of 90%. Density functional theory calculations of the copolymerization process suggest that the high selectivity of poly(tetrathioorthocarbonate)s (PTOCs) originates from the thermodynamically unfavorable elimination of trithiocarbonate anions. In particular, PTOCs can be recycled to the original thiiranes and cyclic trithiocarbonates via spiro intermediates by simple pyrolysis.