Hydrophilic Polyethers Derived from Functional Epoxides: Beyond Poly(ethylene glycol)

ABSTRACT Hydrophilic polymers constitute an essential section in polymer sciences and technologies. Poly(ethylene glycol) (PEG), a flagship hydrophilic polymer derived from the simplest epoxide, has attracted massive research interests and found wide‐ranged applications from daily commodities to cutting‐edge materials. In the meantime, limitations of PEG are increasingly noted, including hazardous nature of its monomer, unfavored crystallinity, lack of modification sites and stimuli‐responsiveness, immunogenicity due to extensive uses, etc., which has heavily spurred explorations for PEG alternatives. This review summarizes the synthetic methods, properties, and applications of non‐PEG hydrophilic polyethers containing methoxyl, hydroxyl, carboxyl, amido, amino, and other polar pendant groups derived from functional epoxide monomers. To a large extent, these polymers maintain the key characters of PEG (e.g. water solubility, biocompatibility), and feature tunable stimuli‐responsiveness (to temperature, pH, oxidation), chemical modifiability, and even degradability. The current challenges and opportunities for future advancement of non‐PEG hydrophilic polyethers are also proposed.