Deformability and solvent penetration in soft nanoparticles at liquid-liquid interfaces.

Area of Science:

• Soft matter physics
• Colloid science
• Materials science

Background:

• The internal structure (topology) and deformability of soft nanoparticles significantly impact their solvent permeability.
• Understanding how nanoparticle network structure influences solvent uptake, invasion, and mixing under confinement is crucial.

Purpose of the Study:

• To investigate the relationship between nanogel topology (ideal vs. realistic networks), cross-linking degree, and solvent permeability at liquid-liquid interfaces.
• To analyze how interfacial strength affects nanogel permeability and internal miscibility.

Main Methods:

• Large-scale molecular dynamics simulations of nanogels at liquid-liquid interfaces.
• Analysis of nanogel permeability using a grid representation accounting for surface fluctuations and particle counts.
• Inclusion of excluded volume interactions for all particles (monomers and liquids).

Main Results:

• Ideal networks exhibit higher liquid uptake and invasive capacity than realistic networks, with differences diminishing at rigid interfaces.
• Optimal uptake and invasion occur at a cross-linking degree dependent on interfacial strength (~15-20% for moderate/stiff interfaces).
• Increased interfacial strength enhances internal nanogel miscibility (up to 5x), with disordered networks showing superior mixing.

Conclusions:

• Nanogel permeability is intrinsically linked to particle deformability and network topology.
• Disordered nanogel networks offer improved mixing and solvent interaction compared to ideal networks, particularly under strong interfacial confinement.
• The degree of cross-linking and interfacial strength are key parameters for optimizing nanogel solvent interactions.