title: The pH-responsive behaviour of poly(acrylic acid) in aqueous solution is dependent on molar mass.
abstract: 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.
authors.affiliation: Department of Chemistry, Brook Hill, University of Sheffield, Sheffield S3 7HF, UK and School of Chemistry and Forensic Sciences, University of Bradford, Richmond Building, Bradford BD7 1DP, UK. s.rimmer@bradford.ac.uk.
authors.forename: Thomas
authors.initials: T
authors.lastname: Swift
authors.affiliation: Department of Chemistry, Brook Hill, University of Sheffield, Sheffield S3 7HF, UK.
authors.forename: Linda
authors.initials: L
authors.lastname: Swanson
authors.affiliation: Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK. mark.geoghegan@sheffield.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Geoghegan
authors.affiliation: Department of Chemistry, Brook Hill, University of Sheffield, Sheffield S3 7HF, UK and School of Chemistry and Forensic Sciences, University of Bradford, Richmond Building, Bradford BD7 1DP, UK. s.rimmer@bradford.ac.uk.
authors.forename: Stephen
authors.initials: S
authors.lastname: Rimmer