Electron Transport through a Diazonium-Based Initiator Layer to Covalently Attached Polymer Brushes of Ferrocenylmethyl Methacrylate

Abstract

A versatile method based on electrografting of aryldiazonium salts was used to introduce covalently attached initiators for atom transfer radical polymerization (ATRP) on glassy carbon surfaces. Polymer brushes of ferrocenylmethyl methacrylate were prepared from the surface-attached initiators, and these films were thoroughly analyzed using various techniques, including X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IRRAS), ellipsometry, and electrochemistry. Of particular interest was the electrochemical characterization of the electron transfer through the diazonium-based initiator layer to the redox centers in the polymer brush films. It was found that the apparent rate constant of electron transfer decreases exponentially with the dry-state thickness of this layer. To investigate the electron transfer in the brushes themselves, scanning electrochemical microscopy (SECM) was applied, thereby allowing the effect from the initiator layer to be excluded. The unusual transition feature of the approach curves recorded suggests that an initial fast charge transfer to the outermost-situated ferrocenyl groups is followed by a slower electron transport involving the neighboring redox units.

Graphene inclusion controlling conductivity and gas sorption of metal–organic framework

“…54 Finally, the functionalised GC plates were sonicated for 5 minutes in acetone (HPLC grade) and dried.…”

Wohl‐Ziegler Bromination of Electrografted Films for Optimizing Atom Transfer Radical Polymerization

“…For the GCBnBr the at. % of bromine is 5–7 times smaller than what was previously achieved by us via the widely used two‐step procedure where the first step is electrografting of 4‐(2‐hydroxyethyl)benzenediazonium followed by post‐modification with α‐bromoisobutyryl bromide . For GCBnCl the at.…”

Side chain effects in the packing structure and stiffness of redox-responsive ferrocene-containing polymer brushes

“…They found that, on the one hand, the anodic peak potential (E pa ) shifted to more positive while the cathodic peak potential (E pc ) shifted to more negative potential resulting in an increase of the peak separation DE p = E pa À E pc from 0.2 eV to 1.2 eV for the same polymer brush measured in the different organic electrolyte solvent (acetonitrile and tetrahydrofuran, respectively); on the other hand, when using the same organic electrolyte solvent (acetonitrile), the broadening of the cathodic peaks is from 0.1 V to 0.4 V (comparing the full width at half maximum) for the different block copolymers (difference in variation of the Fc-containing blocking sequence). Daasbjerg et al [39] studied the electrochemical properties of Fc containing polymer brushes generated on a diazonium-based initiator layer and found that the electron transfer rate exponentially decreased by 1.8 order of magnitude with the dry thickness of this initiator monolayer increasing from 0.5 ± 0.1 to 4.4 ± 0.4 nm.…”