SKM 2023 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 53: Charged Soft Matter, Polyelectrolytes and Ionic Liquid
CPP 53.2: Talk
Thursday, March 30, 2023, 15:30–15:45, ZEU 255
Why weakly hydrated anions bind to polymers but not to monomers? — Bradley A. Rogers1, Halil I. Okur1,4, Chuanyu Yan1, Tinglu Yang1, •Jan Heyda2, and Paul S. Cremer1,3 — 1Department of Chemistry, The Pennsylvania State University, University Park, PA, USA. — 2Department of Physical Chemistry, University of Chemistry and Technology, Prague, Dejvice, Czech Republic. — 3Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA. — 4Present address: Department of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, Ankara, Turkey.
Weakly hydrated anions help to solubilize hydrophobic macromolecules in aqueous solutions, but small molecules comprising the same chemical constituents precipitate out when exposed to these ions. Here, this apparent contradiction is resolved by systematically investigating the interactions of NaSCN with polyethylene oxide oligomers and polymers of varying molecular weight. A combination of spectroscopic and computational results reveals that SCN- accumulates near the surface of polymers, but is excluded from monomers. This occurs because SCN- preferentially binds to the centre of macromolecular chains, where the local water hydrogen-bonding network is disrupted. These findings suggest a link between ion-specific effects and theories addressing how hydrophobic hydration is modulated by the size and shape of a hydrophobic entity.