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

Live today our latest research, carried out in collaboration with Sheffield Professor of Physics Mark Geoghegan, is published with the RSC Journal Soft Matter. This paper outlines how even the simplest ‘smart’ polymer model shows unusual and unobserved behaviour despite the maturity of the field.

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.

Poly(acrylic acid)

The full paper can be found at Soft Matter.