Tuning Steady Shear Rheology through Active Dopants

Area of Science:

• Soft matter physics
• Rheology
• Statistical mechanics

Background:

• Active Brownian particles (ABPs) exhibit self-propulsion, leading to unique dynamic behaviors.
• Mixtures of active and passive particles are crucial for understanding complex material properties.
• Controlling rheological properties of soft materials is vital for various applications.

Purpose of the Study:

• To numerically investigate the steady shear rheology of active-passive Brownian particle mixtures.
• To determine the influence of active particle fraction on fluidization and mechanical properties.
• To identify key parameters governing the behavior of these mixtures.

Main Methods:

• Numerical simulations of Brownian dynamics.
• Varying the fraction of active Brownian particles (ABPs) in mixtures.
• Analysis of steady shear rheology and glass transition phenomena.

Main Results:

• Even small fractions of active dopants induce significant fluidization, comparable to fully active systems.
• A combined parameter, 'active energy' (dopant fraction × propulsion speed²), dictates rheology and glass transition.
• The study reveals a quantitative relationship between active dopant concentration and material response.

Conclusions:

• Active dopants offer an efficient strategy for tuning the mechanical properties of soft materials.
• The 'active energy' parameter provides a unified framework for understanding active-passive mixtures.
• This work enables precise control over soft material behavior using minimal active components.