Introducing Vinylthioethyl Glycidyl Ether as a Versatile Platform for Functionalization of Poly(ethylene glycol)

Vinylthioethyl glycidyl ether (VTEGE) is established as a monomer to afford multifunctional poly(ethylene glycol) via anionic ring-opening copolymerization, yielding polyethers with tunable morphology, composition-driven thermal and solubility properties, and versatile post-polymerization reactivity. Increasing the VTEGE content gradually leads to suppression of crystallization and tunability of hydrophilicity. 1H NMR kinetics enabled the determination of the reactivity ratios, showing a nearly ideally random copolymer microstructure. The vinyl thioether moieties underwent selective oxidation to the corresponding sulfoxides and sulfones without compromising polymer integrity. Reaction kinetics and systematic oxidant screening revealed sodium hypochlorite and sodium perborate as suitable oxidizing agents with a very low extent of detectable side reactions. Polymer properties were drastically altered via oxidation, yielding fully water-soluble sulfoxide and sulfone copolymers with a strongly increased glass transition. Additionally, the electron-rich vinyl thioether readily underwent radical crosslinking to form polyether networks with tunable crosslinking densities, which is promising for hydrogels or polyether membranes.