title: In situ Electrochemical Impedance Spectroscopy of Electrostatically Driven Selective Gold Nanoparticle Adsorption on Block Copolymer Lamellae.
abstract: Electrostatic attraction between charged nanoparticles and oppositely charged nanopatterned polymeric films enables tailored structuring of functional nanoscopic surfaces. The bottom-up fabrication of organic/inorganic composites for example bears promising potential toward cheap fabrication of catalysts, optical sensors, and the manufacture of miniaturized electric circuitry. However, only little is known about the time-dependent adsorption behavior and the electronic or ionic charge transfer in the film bulk and at interfaces during nanoparticle assembly via electrostatic interactions. In situ electrochemical impedance spectroscopy (EIS) in combination with a microfluidic system for fast and reproducible liquid delivery was thus applied to monitor the selective deposition of negatively charged gold nanoparticles on top of positively charged poly(2-vinylpyridinium) (qP2VP) domains of phase separated lamellar poly(styrene)-block-poly(2-vinylpyridinium) (PS-b-qP2VP) diblock copolymer thin films. The acquired impedance data delivered information with respect to interfacial charge alteration, ionic diffusion, and the charge dependent nanoparticle adsorption kinetics, considering this yet unexplored system. We demonstrate that the selective adsorption of negatively charged gold nanoparticles (AuNPs) on positively charged qP2VP domains of lamellar PS-b-qP2VP thin films can indeed be tracked by EIS. Moreover, we show that the nanoparticle adsorption kinetics and the nanoparticle packing density are functions of the charge density in the qP2VP domains.
authors.affiliation: DWI - Leibniz Institute for Interactive Materials , Forckenbeckstraße 50, 52056 Aachen, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Wagner
authors.affiliation: Institute of Materials in Electrical Engineering 1, RWTH Aachen University , Sommerfeldstraße 24, 52074 Aachen, Germany.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Lazar
authors.affiliation: Institute of Materials in Electrical Engineering 1, RWTH Aachen University , Sommerfeldstraße 24, 52074 Aachen, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schnakenberg
authors.affiliation: Chair for Polymer Materials and Polymer Technology, University of Potsdam & Fraunhofer Institute for Applied Polymer Research (IAP) , Geiselbergstraße 69, 14476 Potsdam-Golm, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Böker
keywords: adsorption kinetics; block copolymers; electrostatics; impedance spectroscopy; nanoparticles