Degradable and renewably-sourced poly(ester-thioethers) by photo-initiated thiol-ene polymerization

With the aim of preparing sustainable and degradable polymers from sugar-derived precursors, a family of five poly(ester-thioethers) were synthesized by photoinitiated thiol-ene polymerization of monomers incorporating d-glucaro-1,4:6,3-dilactone (GDL). Various dithiols were used to produce linear poly(ester-thioethers) of glucarodilactone 10-undecenoate (GDLU) to probe the effect of the dithiols on the observed mechanical performance and degradability. The samples exhibited glass transition (T_g) values from -8.7 to 19 °C. The polymers with the simplest dithiols, 1,2-ethanedithiol (EtDT) and 3,6-dioxa-1,8-octane-dithiol (DODT), were found to exhibit crystallinity, while the more structurally complex and rigid dithiol structures were found to produce amorphous materials. Due to the GDL units in the polymers, rapid degradation under basic aqueous conditions and stability in acidic and neutral conditions were observed. Tensile testing of these materials showed robust mechanical properties, including tunable moduli (0.011 to 0.29 GPa), strength (21 to 42 MPa), and ductility (410 to 590%).