Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 28: Posters: Biomaterials and Biopolymers
BP 28.2: Poster
Dienstag, 17. März 2015, 14:00–16:00, Poster A
The effect of urea on the swelling and collapse behavior of poly-N-isoproylacrylamide: a computational study — •Julian Michalowsky1, Samantha Micciulla2, Regine von Klitzing2, and Jens Smiatek1 — 1Institut für Computerphysik, Universität Stuttgart, 70569 Stuttgart, Germany — 2Stranski-Laboratorium, Institut für Chemie, Technische Universität Berlin, 10623 Berlin, Germany
The effect of urea on the swelling and collapse properties of poly(N-isopropylacrylamide) (PNIPAM) molecules is presented. The results of all-atom Molecular Dynamics simulations imply that the macroscopic changes induced in the system by the increase of temperature and urea concentration can be related to microscopic details. The numerical simulations elucidate the main mechanism leading to the observed effects, which are the result of a subtle interplay between hydration properties and a concentration-dependent urea binding behavior. In particular, at low osmolyte concentration a small amount of direct bonded urea molecules to PNIPAM in addition to the hydrating water molecules leads to the stabilization of a more extended conformation. In contrast, at high osmolyte concentrations the binding between PNIPAM and urea becomes more favorable such that the number of hydrating water molecules is significantly decreased. Our numerical results therefore imply that a concentration-dependent binding behavior of urea governs the experimentally observed collapse and swelling properties of PNIPAM brushes in aqueous solution.