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Exploring guest molecule uptake in pH-responsive polyelectrolyte microgels via Monte Carlo simulations.
Christian Strauch1, Lars Roß1, Stefanie Schneider1
1Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany. schneider@pc.rwth-aachen.de.
Soft Matter
|December 2, 2024
Summary
Microgel interactions with charged guest molecules were simulated. Higher guest charge initially enhances microgel ionization, but excessive charge causes collapse, while larger guests induce swelling.
Area of Science:
- Polymer Science
- Computational Chemistry
- Materials Science
Background:
- Microgels are crucial nanocarriers, but their interactions with guest molecules like proteins and nanoparticles are complex.
- Predicting microgel system properties is challenging due to increasing complexity.
Purpose of the Study:
- To systematically investigate guest molecule uptake in pH-responsive polyelectrolyte microgels.
- To model guest molecules as charged beads and study their interactions with microgels using Monte Carlo simulations.
Main Methods:
- Monte Carlo simulations of a bead-spring network model for pH-responsive microgels.
- Systematic variation of guest molecule charge, size, and number, alongside salt concentration.
- Analysis of microgel ionization, swelling, and guest molecule uptake dynamics.
Main Results:
- Higher guest molecule charge enhanced microgel ionization at low pH, with optimal effect at z=+15.
- Excessive guest charge led to microgel collapse due to incomplete charge compensation.
- Increased guest size caused microgel swelling due to excluded volume effects.
- Monovalent salt slightly decreased uptake at low ionization; higher valency salt further reduced uptake in fully ionized microgels.
Conclusions:
- Guest molecule properties significantly influence microgel behavior, including ionization and swelling.
- Electrostatic interactions and excluded volume effects are key drivers of guest uptake and microgel response.
- Simulation insights are vital for designing microgels as advanced nanocarriers.
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