Friction mediated by redox-active supramolecular connector molecules
B L Bozna1, J Blass1, M Albrecht
1INM - Leibniz-Institute for New Materials, 66123 Saarbrücken, Germany.
Langmuir : the ACS Journal of Surfaces and Colloids
|September 15, 2015
Summary
We explored nanoscale friction using atomic force microscopy, finding that ferrocene connector molecules significantly increase friction. Electrochemical control of ferrocene
Area of Science:
- Nanotechnology
- Surface Science
- Supramolecular Chemistry
Background:
- Friction is a critical phenomenon at the nanoscale, influenced by surface interactions.
- Supramolecular chemistry offers novel ways to control surface interactions through molecular recognition.
- Cyclodextrins and ferrocene derivatives are key components in host-guest chemistry.
Purpose of the Study:
- To investigate the role of ferrocene-based connector molecules in modulating nanoscale friction.
- To explore the influence of electrochemical control on friction at functionalized surfaces.
- To understand the dynamics of supramolecular complex formation and its effect on friction.
Main Methods:
- Atomic force microscopy (AFM) was employed to measure friction at the nanometer scale.
- Electrochemical control was applied to modify the state of ferrocene connector molecules.
- Isothermal titration calorimetry (ITC) was used to study the binding kinetics of supramolecular complexes.
Main Results:
- Ferrocene connector molecules increased friction by up to a factor of 12 compared to controls.
- Electrochemical oxidation of ferrocene to ferrocenium decreased friction due to altered complex stability.
- Switching electrochemical potentials resulted in reversible friction changes between 1.2-1.8.
- ITC confirmed fast dissociation and rebinding kinetics, indicating an equilibrium regime.
Conclusions:
- Nanoscale friction can be effectively tuned using electrochemically switchable supramolecular interactions.
- Ferrocene-cyclodextrin complexes provide a responsive system for controlling surface friction.
- This work demonstrates a novel approach for developing switchable nanotribological surfaces.
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