In conclusion, we introduced a ring-opening terpolymerization (ROTERP) process to produce sulfur-containg polymer materials from commercially relevant epoxides, carbon disulfide and elemental sulfur waste. The process requires trace amounts of a cheap lithium alkoxide catalyst and occurs without external heating. Mechanistic investigations showed that S8 insertion leads to more facile propagation thereafter which enables the sequence selectivity. As the R-S-Sy-R links in the polymer remain susceptible towards nucleophilic attack by thiolate intermediates one can crosslink the chains in-situ with multifunctional thiols producing reprocessable and degradable networks. Our report demonstrates how mechanistic understanding in alkali metal catalysis can turn waste S8 with commercially viable comonomers into complex polymers with tunable properties, reprocessability and degradability.