To validate this hypothesis, we tested the degradation of the modified PEO and the detection of carboxylic acid under hydrolysis conditions. Specifically, we placed benzoic acidattached PEO (Mn = 13.4 kg/mol, 3.1 mol% benzoic esters) in D2O and monitored the release of benzoic acid via 1 H NMR spectroscopy (Figure ). The resulting spectra of the functionalized PEO featured broad aromatic peaks (green dots) from the polymeric benzoates.