Percolation in binary mixtures of linkers and particles: Chaining vs branching

Area of Science:

• Colloid and Interface Science
• Materials Chemistry
• Statistical Mechanics

Background:

• Equilibrium gels form from colloidal particles and linker species.
• Linkers can self-assemble into chains, influencing particle aggregation.
• Patchy particles with specific binding sites (C, A, B) are used.

Purpose of the Study:

• Investigate gel formation in a binary mixture of particles and self-assembling linkers.
• Analyze the percolation behavior of two distinct bonding models (A and B).
• Understand how linker chaining affects gelation and percolation thresholds.

Main Methods:

• Utilized a generalized Flory-Stockmayer theory.
• Employed Monte Carlo simulations.
• Studied two models with different linker-particle bonding strategies (AC vs. BC bonds).

Main Results:

• Linker self-assembly into chains reduces the required particle fraction for percolation in both models.
• Model B shows percolation induced by high particle fractions.
• Percolation by heating and percolation loops were observed in model A under specific conditions.
• A model-dependent relationship between chaining and branching at percolation was identified.

Conclusions:

• Linker chaining significantly impacts colloidal gel formation and percolation.
• The bonding strategy between linkers and particles (model A vs. B) dictates the percolation behavior.
• Longer linker chains necessitate less branching for achieving percolation at a given composition.