Dynamic Circular Sulfur-Rich Polymer Glasses From Elemental Sulfur

Elemental sulfur (S₈) is a commodity-priced petroleum byproduct suitable for upcycling as a neat molten medium for sustainable polymer synthesis. Inverse vulcanization is an attractive approach for converting S₈ into sulfur-rich plastics, yet scalable manufacturing remains challenging. The chemistry of molten sulfur is poorly understood, limiting progress using this unconventional medium. Herein, molten sulfur homogeneity is identified as a critical parameter for accessing sulfur-rich (70-80 wt.%) polymer glasses, termed inverse vulcanized glass (IVG). Application of ultra-high-purity sulfur melts uncovers a hidden boundary condition governing sulfur plastic manufacturing, enabling fabrication of large IVG precision optics with high refractive index and landmark broadband transparency across the visible-infrared spectrum. The inclusion of S-S bonds afford covalent adaptable networks with rheology dominated by dynamic bond reorganization. IVG functions as an affordable, broadband Vis-IR optical glass whose damaged components can be melt-reprocessed, providing a circular advantage over traditional inorganic optical materials.