Polyglycidamides: from Backbone-Promoted Amidation to Degradable Polyether with Wide-Range LCST

Amide groups occur extensively in natural and synthetic polymers cultivating their vital roles in biological and industrial worlds. We report here an efficient and controlled pathway to amide-functionalized polyethers through ring-opening polymerization (ROP) of commercially available ethyl glycidate followed by amidation of the pendant ester groups. Transesterification is inhibited during the ROP by use of a two-component organocatalyst. Surprisingly, amidation can be completed even at 0 °C uncatalyzed, which is attributed to the electron-withdrawing effect of the oxygenated backbone as well as the inter-/intra-chain hydrogen bonding. Also interestingly, ethylene glycol and water are found to further accelerate the amidation while suppressing backbone degradation. The obtained polyglycidamides (PGAms) exhibit aqueous thermoresponsive properties, similar to their carbon-chain counterparts (polyacrylamides). Cloud point can be linearly modulated by co-amidation using two amines of varied ratios. Unlike polyacrylamides and regular polyethers, PGAm is degradable through retro-oxa-Michael addition under basic conditions.