SKM 2021 – wissenschaftliches Programm
CPP 8.30: Poster
Mittwoch, 29. September 2021, 17:30–19:30, P
Highly Metastable Switchable Surfaces Based on Polymer Brushes Containing End-Adsorbing Chains — •Markus Koch1, Dirk Romeis1, and Jens-Uwe Sommer1,2 — 1Institute Theory of Polymers, IPF Dresden, Germany — 2Institute Theory of Physics, TU Dresden, Germany
We investigate a switchable polymer brush system that responds to external stimuli by adsorbing (hiding) or exposing specific functional groups. Our design enables targeted changes to the properties of a surface, e.g. to change the interactions with the environment or increase the density of functional groups below the brush. The system consists of a monodisperse polymer brush containing a small fraction of end-modified minority chains. The length of these chains differs from the brush and their end groups can adsorb at the grafting surface. We study this system using Scheutjens-Fleer SCF calculations, MD simulations, and analytical theory . The conformational changes of the admixed chains depend on their relative length and the attraction of their end groups to the surface. Based on the free energy profiles of the adsorption transition, we extract free energy barriers, that are in good agreement with our theoretical predictions. The barriers are strongly reduced when the brush is collapsed, for instance, via a solvent change. Thus, the system can be tuned to obtain a reversible or irreversible end-adsorption behavior. Financial support by the DFG, project SO 277/17-1, is gratefully acknowledged.
 Koch, M., Romeis, D., Sommer, J.-U., Macromolecules 53 (17), 7356-7368 (2020)