Department of Physics, Engineering Physics & Astronomy

Queen's University
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Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Controlling Polyelectrolyte Brush Structure

Tyler Shendruk
University of Ottawa

Thursday, April 11, 2013
10:30 AM @ Stirling 501

Abstract:

Surface modification by coating polymer chains to interfaces offers a well-developed path for nanoengineering smart surfaces that can respond to external stimuli. The response of charged polymer brushes subject to external electric fields that are applied normal to the grafting surface is currently of particular interest since applied voltage is a convenient switching mechanism and suggests designs for controllable gates as components in micro- and nanofluidic devices.

We will describe our study of this system using simulations of salt-free polyelectrolyte brushes. Our simulations demonstrate that there exists a critical field strength, below which the brush remains relatively unchanged due to the balance between the chains’ elastic energy and the counterion osmotic pressure. But, above this critical field the brush-counterion complex polarizes initiating structural changes within the brush. We find that electric field strength could tailor surface structure and give fine control over surface friction and flow resistance in microfluidic devices or be useful in analyte capture using an alternating field.