Understanding Anti-Polyelectrolyte Effect in Polyzwitterions Using Coarse-Grained Molecular Dynamics Simulations.
Akshay Chauhan1, Srabanti Chaudhury1
1Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008 Maharashtra, India.
The Journal of Physical Chemistry. B
|March 17, 2025
Summary
Polyzwitterions (PZs) show unique salt-induced conformational changes, unlike typical polymers. Their solubility and viscosity increase with salt, a key finding for advanced material applications.
Area of Science:
- Polymer Science
- Materials Science
- Computational Chemistry
Background:
- Polyzwitterions (PZs) possess both positive and negative charges per repeating unit.
- PZs exhibit an antipolyelectrolyte effect, increasing solubility/viscosity with salt.
- They serve as synthetic analogs for intrinsically disordered proteins.
Purpose of the Study:
- Investigate the conformational properties of polyzwitterions in salt solutions.
- Determine how structural parameters (dipolar side chain spacing 'd', chain length 'N') influence PZ conformation.
- Understand the nonmonotonic effects of salt concentration on PZ behavior.
Main Methods:
- Coarse-grained Langevin dynamics simulations were employed.
- Simulations focused on aqueous solutions with varying salt concentrations.
- Analysis centered on the radius of gyration and conformational changes.
Main Results:
- Added salt induced nonmonotonic changes in the polymer's radius of gyration.
- Both antipolyelectrolyte and polyelectrolyte effects were observed depending on salt concentration.
- These effects are linked to ion-mediated charge regulation and dipole-dipole interaction screening.
Conclusions:
- Salt concentration plays a critical role in controlling polyzwitterion conformations.
- Understanding these salt-dependent behaviors is crucial for designing PZs for specific applications.
- Applications include antimicrobial materials, drug delivery, and polymer electrolytes.
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