Polymer‐Modified Mesoporous Silica Thin Films for Redox‐Mediated Selective Membrane Gating

Abstract

Controlling structure and function to switch ionic transport through synthetic membranes is a major challenge in the fabrication of functional nanodevices. Here we describe the combination of mesoporous silica thin fi lms as structural unit, functionalized with two different redox-responsive ferrocene-containing polymers, polyvinylferrocene (PVFc) and poly(2-(methacryloyloxy)ethyl ferrocenecarboxylate) (PFcMA), by using either a grafting to, or a grafting from approach. Both mesoporous fi lm functionalization strategies are investigated in terms of polymer effect on ionic permselectivity. A signifi cantly different ionic permselective behavior can be observed. This is attributed to different polymer location within the mesoporous fi lm, depending on the functionalization strategies used. Additionally, the infl uence of chemical oxidation on the ionic permselective behavior is studied by cyclic voltammetry showing a redox-controlled membrane gating as function of polymer location and the pH value. This study is a fi rst step of combining redox-responsive ferrocene-containing polymers and mesoporous membranes, and thus towards redox-controlled ionic transport through nanopores.

Porous Carbons – Hyperbranched Polymers – Polymer Solvation

“…Pores were established in block-copolymer thin films on gold electrodes [598]. The accessibility of pores could be modulated by the oxidation state of the ferrocene-containing polymers [599].…”

Redox-responsive polymeric membranes via supermolecular host–guest interactions

“…Redox-responsive porous polyelectrolyte membranes which showed general redox-responses were prepared from poly(ferrocenylsilane)-based poly(ionic liquid)s by Vancso et al [15]. Elbert et al reported silica thin films functionalized with ferrocene-containing polymers, which showed a redox-responsive ionic permselectivity [8]. Therefore, the design of smart membranes with apparently redox-responsive hydraulic permeability is urgent desired.…”

“…Numerous studies on redox-responsive materials have been executed nowadays. These materials have great potential in applications of controlled release or drug delivery [1][2][3][4], self-healing [5,6], switching surface properties [7,8], electrically induced optical properties [9,10] and sol-gel transition [11][12][13], due to their responses to external and/or internal redox-stimuli signals.…”

Ferrocene-Modified Block Copolymers for the Preparation of Smart Porous Membranes

“…In the field of (nano)porous structures, ionic permeation across smart membranes have been modulated by introducing redox-active moieties or polymers at the inner pore walls of the membrane [25][26][27][28]. Elbert et al reported on the modification of mesoporous silica membranes with redox-responsive ferrocene-containing polymers by a grafting to and a grafting from approach [29]. Within this approach, successful redox-mediated ion permselectivity in mesoporous membranes was shown.…”