Particles in polymer-functionalized microchannels: electrochemical experiments and molecular dynamics simulations

Abstract

The aim of this thesis has been to provide the ground work for the electrochemical sensing of analytes in polymer-functionalized microchannels via gold-coated microfabricated microchannel electrodes and for the in-situ study of the adsorption of particles in polymer brushes through molecular dynamics simulations. Both these objectives encompass polymer systems that are out of equilibrium and reveal how particles interact with these polymers. The aim was accomplished via the successful fabrication of in-channel gold-coated electrodes within a microfluidic device. To these gold-coated electrodes a redox-active polymer, poly(ferrocenylsilane) (PFS), was attached, via which sodium ascorbate could be sensed. To further understand the effect of particles in polymer systems, molecular dynamics (MD) simulations were performed on the insertion of particles of various size, shape and orientation, into a polymer brush. The force-distance curves were successfully modelled by two different models, one using scaling arguments and one aided through MD. Furthermore, the effect of shaking the wall, to which the polymer brushes are attached, on the penetration depth of particles into the brush was simulated, to approximate biological microsystems. From these could be concluded that if the brush is oscillated at its resonance frequency at a complementary resonance amplitude, the increase in penetration depth is at its maximum.