The pH-responsive behaviour of poly(acrylic acid) in aqueous solution is dependent on molar mass Article Swipe

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Thomas Swift , Linda Swanson , Mark Geoghegan , Stephen Rimmer ·

YOU? · · 2016 · Open Access · · DOI: https://doi.org/10.1039/c5sm02693h · OA: W2288268375

Fluorescence spectroscopy on a series of aqueous solutions of poly(acrylic acid) containing a luminescent label showed that polymers with molar mass, Mn < 16.5 kDa did not exhibit a pH responsive conformational change, which is typical of higher molar mass poly(acrylic acid). Below this molar mass, polymers remained in an extended conformation, regardless of pH. Above this molar mass, a pH-dependent conformational change was observed. Diffusion-ordered nuclear magnetic resonance spectroscopy confirmed that low molar mass polymers did not undergo a conformational transition, although large molar mass polymers did exhibit pH-dependent diffusion.