Synthesis of poly(ester disulfide)s from S₈-involved step-growth addition polymerization at ambient temperature

Elemental sulfur (S₈), an abundant petroleum byproduct, is leveraged as a linchpin monomer in an organobase-catalyzed step-growth addition polymerization with dithiols and diacrylates at ambient temperature. This method enables the scalable synthesis of poly(ester disulfide)s-featuring alternating ester and disulfide linkages-with exceptional atom economy ( > 95% yield), M_n up to 42.0 kDa, and dual functionality: biodegradable ester units and stimuli-responsive disulfides. Mechanistic studies reveal a chemoselective three-component coupling involving S₈ ring-opening, disulfide anion formation, and Michael addition, quantitatively generating symmetric and asymmetric disulfides in near-equimolar ratios. Thermal and mechanical characterizations of the poly(ester disulfide)s reveal programmable properties: High thermal stability (T_d,5% = 248-281 °C), tunable phase behavior (amorphous T_g = -64 °C to semicrystalline T_m = 142 °C), and reductive degradation. By overcoming traditional limitations of harsh conditions and monomer scope, this strategy establishes S₈ as a versatile feedstock for functional polymers, opening avenues for dynamic materials in biomedicine and environmental remediation.