(Top) ATR-IR of the carbonyl region of (top) PAA standard and (middle) diblock p[(AA)48-b-(nBA)50] in D2O with 500 mM NaCl at the pD’s indicated. (bottom) Plot of pD vs % carboxylate from ATR-IR data of PAA standard (○) and diblock p[(AA)48-b-(nBA)50] (●). Carboxylate percentage was calculated from total carbonyl peak intensities of acid, carboxylate, and new peak at 1710, 1560, and 1672 cm−1, respectively.