Dresden 2014 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 56: Colloids and Complex Liquids IV
CPP 56.2: Vortrag
Freitag, 4. April 2014, 09:45–10:00, ZEU 260
Rationalizing Polymer Swelling and Collapse under Attractive Cosolvent Conditions — •Jan Heyda1 and Joachim Dzubiella1,2 — 1Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin, Germany — 2Department of Physics, Humboldt-University Berlin, Newtonstr. 15, 12489 Berlin, Germany
The collapse and swelling behavior of a generic homopolymer is studied using implicit-solvent, explicit-cosolvent Langevin dynamics computer simulations for varying interaction strengths. Maximal swelling is observed if both monomer-monomer and monomer-cosolute interactions are weakly attractive. In the most swollen state the cosolute density inside the coil is remarkably bulk-like and homogenous. Highly attractive monomer-cosolute interactions, induce a chain collapse with considerably enhanced cosolute density within the globule, in strong contrast to the collapse in purely repulsive cosolvents. Thus, similarly appearing collapsed states may result from very different mechanisms with distinct final structural and thermodynamics. Two theoretical models, one based on an effective one-component description, and a fully two-component Flory – de Gennes like model, are in accord with simulation findings. In particular, the polymer collapse in highly attractive cosolvents driven by crosslinking-like bridging effects is reproduced. Next, swelling in predicted only for not too short-ranged interactions. Our findings has implications for cosolute effect on conformations of biomolecules, in particular for highly attractive cosolutes, such as urea, GdmCl, NaI, or NaClO4 near peptide-like moieties.