Polyethers like poly(ethylene glycol) have been widely used for a variety of valuable applications, although their functionalization still poses challenges due to the absence of functional handles along the polymer backbone. Herein, a series of novel azide-functionalized glycidyl ether monomers are presented as a universal approach to synthesize functional polyethers by post-polymerization modification. Three azide-functionalized glycidyl ether monomers possessing different alkyl spacers (ethyl, butyl, and hexyl) were designed and synthesized by a simple two-step substitution reaction. Organic superbase-catalyzed anionic ring-opening polymerization can proceed under mild conditions compatible with an azide pendant group, affording wellcontrolled azide-functionalized polyethers with low dispersity (Đ < 1.2). The azide pendant groups on the resulting polymers were readily modified to a variety of functional groups via copper-catalyzed azide−alkyne cycloaddition reactions and Staudinger reduction. Furthermore, copolymerization of azidohexyl glycidyl ether with allyl glycidyl ether was demonstrated to provide an additional orthogonal functional handle. We anticipate that this work provides a new platform for the preparation of diverse functional polyethers.

Prodrug-type polymer–drug conjugates based on highly biocompatible functional polyethers are developed through mechanochemical post-polymerization modification. Herein, we design functional epoxide monomers of ethoxyethyl glycidyl ether (EEGE) and azidohexyl glycidyl ether (AHGE) and synthesize diblock copolyethers of PEEGE-b-PAHGE via sequential anionic ring-opening polymerization. Subsequent conversion of the functional monomers to the corresponding hydroxyl and amine groups allows for the preparation of double hydrophilic block copolyethers. Most notably, mechanochemical modification allows for the conjugation of these polymers with a highly hydrophobic and potent anticancer agent, cinnamaldehyde, through an imine linkage. The self-assembly of the resulting polymer–drug conjugates into polymeric micelles is characterized by dynamic light scattering and atomic force microscopy. The pH-responsive cleavage of the imine linkages under acidic conditions leads to the release of cinnamaldehyde with a concomitant disassembly of the polymeric micelles. The superior biocompatibility coupled with the solvent-less mechanochemical conjugation approach provides a convenient means to introduce various therapeutics for smart drug delivery.

Although interest in stabilized α-helical peptides as next-generation therapeutics for modulating biomolecular interfaces is increasing, peptides have limited functionality and stability due to their small size. In comparison, α-helical ligands based on proteins can make steric clash with targets due to their large size. Here, we report the design of a monomeric pseudo-isolated α-helix (mPIH) system in which proteins behave as if they are peptides. The designed proteins contain α-helix ligands that do not require any covalent chemical modification, do not have frayed ends, and importantly can make sterically favorable interactions similar to isolated peptides. An optimal mPIH showed a more than 100-fold increase in target selectivity, which might be related to the advantages in conformational selection due to the absence of frayed ends. The α-helical ligand in the mPIH displayed high thermal stability well above human body temperature and showed reversible and rapid folding/unfolding transitions. Thus, mPIH can become a promising protein-based platform for developing stabilized α-helix pharmaceuticals.