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Updated: Jun 28, 2025
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Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
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Effect of Counterion Size on Knotted Polyelectrolyte Conformations
Andrea Tagliabue1,2, Cristian Micheletti2, Massimo Mella1
1Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell'Insubria, via Valleggio 11, Como 22100, Italy.
The Journal of Physical Chemistry. B
|April 22, 2024
Summary
The size and shape of knotted polymers depend on counterion diameter. Both small and large counterions localize knots, while medium ones delocalize them, offering new material design possibilities.
Area of Science:
- Polymer Physics
- Soft Matter Physics
- Computational Chemistry
Background:
- Knotted circular strong polyelectrolytes (PEs) exhibit complex conformational behavior in solution.
- The influence of counterion (CI) properties on PE conformation is crucial for understanding their behavior.
Purpose of the Study:
- To investigate the effect of counterion diameter on the conformational properties of knotted circular strong polyelectrolytes.
- To explore the mechanisms of conformational changes and the role of free energy landscapes.
- To identify potential strategies for external control over PE size and shape.
Main Methods:
- Langevin dynamics simulations.
- Coarse-grained primitive model of electrolytes.
- Analysis of gyration radius, knot length, and free energy landscapes.
Main Results:
- Counterion diameter significantly affects PE gyration radius and knot length in a non-monotonic manner.
- Small and bulky counterions promote knot localization, while medium-sized ones favor delocalized knots.
- Conformational transitions between localized and delocalized knots are driven by enthalpic and entropic trade-offs related to counterion condensation.
Conclusions:
- Counterion characteristics offer a tunable parameter for controlling knotted polyelectrolyte conformation.
- Understanding these interactions enables the design of novel responsive polyelectrolyte-based materials.
- The findings provide a foundation for precise external adjustability of polyelectrolyte size and shape.
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