Use of neutron reflectivity to measure the dynamics of solvation and structural changes in polyvinylferrocene films during electrochemically controlled redox cycling

Glidle, A., Hillman, A.R., Rydeo, K.S., Smith, E.L., Cooper, J.M. , Gadegaard, N. , Webster, J.R.P., Dalgliesh, R. and Cubitt, R. (2009) Use of neutron reflectivity to measure the dynamics of solvation and structural changes in polyvinylferrocene films during electrochemically controlled redox cycling. Langmuir, 25(7), pp. 4093-4103. (doi:10.1021/la803234e)

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Publisher's URL: http://dx.doi.org/10.1021/la803234e

Abstract

Time-resolved specular neutron reflectivity measurements are presented and interpreted for electroactive polyvinylferrocene (PVF) films subject to potentiodynamic electrochemical control. New data acquisition methodology allows an effective measurement time scale on the order of seconds, which is an improvement over conventional methodology by 2 to 3 orders of magnitude. Reflectivity profiles were obtained for PVF films exposed to aqueous 0.1 M NaClO4 in which PVF films are thermodynamically permselective, with contrast variation via H2O and D2O. Irrespective of any model, the raw profiles show chemically reversible film "breathing" due to redox-driven solvent entry and exit during polymer oxidation and reduction, respectively. Modeling reveals three compositionally distinct regions within the polymer film: interfacial regions at the electrode and solution interfaces and a "bulk" interior. The new methodology, supported by simultaneous in situ visible transmission spectroscopy, reveals an unprecedented level of insight into the temporal and spatial mechanistic details of film solvation changes, including a two-stage (de)solvation mechanism for redox switching, differences in interior (in)homogeneity for reduced and oxidized films, and permselectivity failure under dynamic electrochemical conditions for the reduced (but not oxidized) state, in contrast to static conditions that allow permselectivity for both states.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Glidle, Dr Andrew and Cooper, Professor Jonathan and Gadegaard, Professor Nikolaj
Authors: Glidle, A., Hillman, A.R., Rydeo, K.S., Smith, E.L., Cooper, J.M., Gadegaard, N., Webster, J.R.P., Dalgliesh, R., and Cubitt, R.
Subjects:T Technology > TK Electrical engineering. Electronics Nuclear engineering
College/School:College of Science and Engineering > School of Engineering > Biomedical Engineering
Journal Name:Langmuir
ISSN:0743-7463
ISSN (Online):1520-5827
Published Online:29 December 2008

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