Dresden 2011 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 6: Charged Soft Matter
CPP 6.9: Talk
Monday, March 14, 2011, 16:30–16:45, ZEU 160
Selective Adsorption of Spherical Polyelectrolyte Brushes onto Polyelectrolyte Multilayers — •Christoph Hanske1, Alexander Wittemann2, and Andreas Fery1 — 1Department of Physical Chemistry II, University of Bayreuth, Germany — 2Department of Physical Chemistry I, University of Bayreuth, Germany
Ordered mesostructures of functional colloids are promising building blocks for future lab-on-a-chip devices such as sensors. The production of these materials requires precise control over the effective particle-substrate interactions. Here we discuss the electrosteric interaction between polyelectrolyte multilayers and spherical polyelectrolyte brushes (SPB). These colloids consist of a glassy core and a stimuli-responsive layer of densely grafted polyelectrolyte chains. The polyelectrolyte brush allows tuning the shape of the particles in solution as well as adjusting their adsorption behavior in the presence of charged surfaces. Kinetic studies at low ionic strength reveal rapid SPB adsorption on oppositely charged substrates, whereas equally charged surfaces efficiently prevent colloidal attachment. This marked selectivity results from the particle morphology and can be explained in terms of counterion release and electrosteric repulsion. The extent of particle adsorption depends sensitively on electrostatic screening. With increasing ionic strength, the equilibrium surface coverage is raised on both types of substrate at the expense of selectivity. Accounting for this parameter, we were able to assemble two-dimensional arrays of SPB utilizing chemically patterned substrates.