Connectivity percolation in suspensions of hard platelets

Area of Science:

• Physics
• Materials Science
• Statistical Mechanics

Background:

• Percolation theory describes the formation of connected clusters in disordered systems.
• Anisotropic particles are often assumed to follow a simple scaling law for percolation thresholds based on aspect ratio.
• Hard platelets are model systems for studying anisotropic particle behavior.

Purpose of the Study:

• To investigate connectivity percolation in suspensions of hard platelets.
• To determine how the aspect ratio of platelets influences the percolation threshold.
• To understand the underlying mechanisms governing percolation in these systems.

Main Methods:

• Monte Carlo simulations were employed to model connectivity percolation.
• A contact-volume argument using an effective single-particle cell model was used for interpretation.
• The influence of particle aspect ratio on percolation was systematically studied.

Main Results:

• The percolation threshold for hard platelets is nonmonotonic with respect to aspect ratio.
• A shallow minimum in the percolation threshold was observed at intermediate aspect ratios.
• The isotropic-nematic transition was found to preempt the percolation transition, affecting the threshold.

Conclusions:

• The common assumption of inverse aspect ratio scaling for percolation thresholds does not hold for hard platelets.
• Platelike fillers, such as graphene, may not be effective for achieving low-concentration conduction in composites due to this nonmonotonic behavior.
• Understanding percolation in anisotropic systems is crucial for designing functional materials.