Polymer functionalization through postpolymerization modification (PPM) is a promising route for rapid and efficient polymer modification. However, direct C-H bond functionalization of poly(ethylene oxide) (PEO) has been challenging and not extensively explored. Historically, C-H bonds have been regarded as inert and crucial for providing molecular stability. Nonetheless, recent advances in synthetic methodologies have enabled the precise manipulation of C-H bonds with high efficiency and precision. Among hydrocarbons, the relatively weak C-H bond strength of ether units has led to the development of methods for activating and attaching various structures to ethereal C-H bonds. However, successful modification of polymeric ethers remains limited. Although some PEO PPMs have focused on direct oxidation to enhance degradability, only a few reports have been published.