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Solid-state Graft Copolymer Electrolytes for Lithium Battery Applications
Published on: August 12, 2013
Polyelectrolyte adsorption kinetics under an applied electric potential: Strongly versus weakly charged polymers
Christel Olsen1, Paul R Van Tassel
1Department of Chemical Engineering, Yale University, New Haven, CT 06520-8286, USA.
Journal of Colloid and Interface Science
|November 4, 2008
Summary
Continuous polyelectrolyte adsorption is possible for strongly charged polymers via counterion condensation, not just deprotonation. This finding enables controlled nanofilms with permanent charges.
Area of Science:
- Polymer Science
- Electrochemistry
- Surface Science
Background:
- Previous studies showed continuous adsorption of weakly basic polycations on conducting substrates under anodic potential.
- Continuous adsorption requires interfacial charge regulation, often achieved through segment deprotonation in weakly charged polymers.
Purpose of the Study:
- To investigate if deprotonation is essential for continuous polyelectrolyte adsorption.
- To compare the adsorption behavior of weakly and strongly charged polyelectrolytes on indium tin oxide (ITO).
Main Methods:
- Optical waveguide lightmode spectroscopy (OWLS) was used to measure adsorption.
- Adsorption of poly(N-vinyl imidazole) (PVI) and quaternized poly(N-vinyl imidazole) (QPVI) was studied under various conditions (open circuit, applied potential, different salt concentrations).
Main Results:
- Under open circuit, both PVI and QPVI showed rapid, irreversible adsorption.
- At 1.5 V (vs. H) in 0.1 M NaCl, both PVI and QPVI exhibited continuous and reversible adsorption.
- In salt-free solution at 1.5 V, only PVI showed continuous adsorption, and both polymers adsorbed irreversibly.
Conclusions:
- Interfacial charge regulation occurs via deprotonation for PVI and counterion condensation for QPVI.
- Continuous adsorption is achievable for strongly charged polyelectrolytes through counterion condensation.
- This research facilitates the creation of nanofilms with controlled polymer content, including those with permanent charges.
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