| AVS 60th International Symposium and Exhibition | |
| In Situ Spectroscopy and Microscopy Focus Topic | Thursday Sessions |
| Session IS+EN+SP+SS-ThA |
| Session: | In Situ Studies of Electrochemical Interfaces and Processes |
| Presenter: | M. Valtiner, Max Planck Institut fur Eisenforschung GmbH, Germany |
| Authors: | M. Valtiner, Max Planck Institut fur Eisenforschung GmbH, Germany S.H. Donaldson, University of California, Santa Barbara K. Kristiansen, University of California, Santa Barbara M.A. Gebbie, University of California, Santa Barbara J.N. Israelachvili, University of California, Santa Barbara |
| Correspondent: | Click to Email |
Redox-active interfaces are ubiquitous in the realms of natural and technological systems. For instance, prevention of corrosive delamination at metal|oxide|paint interfaces, or bio-mimicry of adhesive bonding in natural systems (e.g. mussel glues) rely on a fundamental understanding of interaction forces at electrified and/ or redox-active solid|liquid|softmatter interfaces. Recently, we developed a newly designed electrochemical surface forces apparatus setup (EC-SFA) that allows control and measurement of both surface potentials and interfacial electrochemical reactions with simultaneous measurement of normal interaction forces and the absolute distances between (similar or dissimilar) apposing surfaces [1], [2].
To quantify both oxide growth and interaction forces between asymmetric apposing softmatter and metal surfaces we performed normal force measurements across atomically smooth polarized gold electrodes facing PEGolated lipid bilayers with different head-group chemistries. Switching electrochemical potentials allowed us to quantitatively and qualitatively identify, rationalize, and therefore control, which interaction forces dominated between the electrode surfaces and a surface coated with differently end-functionalized polyethylene glycol (PEG) polymers. In particular, the manipulation of surface potentials and the oxidation of the gold have profound and very strong influences on the measured interaction forces. Moreover, our measurements allowed us to in-situ quantify the Au-oxide thickness with Ångstrom accuracy. Here, we will discuss in detail, how (1) electric double layer potentials, (2) change of surface chemistry (e.g. oxide growth, oxide thickness) as well as (3) polymer chemistry (functional groups and backbone chemistry) influence specific and non-specific interaction forces (electrostatic, hydrophobic and Van der Waals forces, see also [3]) across electrified softmatter|metal interfaces.
[1] Valtiner, M., Kristiansen, K., Greene, G. W. et al. in Advanced Materials 23, 2294 (2011).
[2] Valtiner, M., Banquy, X., Kristiansen et al. in Langmuir 28, 13080-13093 (2012).
[3] Valtiner, M., Donaldson, S. H., Jr., Gebbie, M. A. et al. in Journal of the American Chemical Society 134, 1746-1753 (2012).